Monday 27 May

"Monday 27 May"

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00:00 - 00:00 #39974 - Surface topography assessment of the wax patterns produced by material jetting technology for investment casting.
Surface topography assessment of the wax patterns produced by material jetting technology for investment casting.

Investment casting, a widely employed manufacturing process in the production of intricate metal components, relies heavily on the quality and precision of the initial wax patterns [1]. The growing adoption of Material Jetting Technology (MJT), a type of Additive Manufacturing (AM) [2], for crafting these wax patterns necessitates a comprehensive understanding of the resulting surface characteristics. The investigation begins with an in-depth exploration of the MJT process, emphasizing its relevance in creating intricate and complex geometries typical of investment casting wax patterns (see Fig. 1a). The focus is to identify the influence of key process parameters on the surface finish of the printed wax patterns [3]. The material jetting method allows for the layer-by-layer deposition of wax material, and a detailed analysis is conducted to assess the impact of layer thickness, print resolution, build orientation, and geometrical design on the final properties of the wax patterns [4]. Subsequently, the study transitions to the Investment casting phase, scrutinizing the translated qualities of the 3D-printed wax patterns into the casted metal components. Figure 2 displays the casted metal components using the 3Dialog CeraCaster® MJT machine and the Investment casting process. Emphasis is placed on evaluating the fidelity of the casted parts to the original design and investigating any deviations in surface finish introduced during the casting process. Factors such as mold quality, casting temperature, and cooling rates are analyzed for their influence on the outcome.[5] Characterization technique to conduct the assessment, including interferometry for surface roughness analysis (see Fig. 1b). The study aims not only to quantify the surface finish but also to identify correlations between the MJT process parameters, wax pattern qualities, and the subsequent casting results. The findings of this research are anticipated to provide valuable guidelines for practitioners in various fields such as dentistry, jewelry, automotive, aerospace applications, and so on, providing the tool for optimization of MJT parameters for enhanced surface finish in wax patterns intended for Investment Casting. Moreover, the study contributes to the field of hybrid manufacturing, involving the integration of AM technologies and traditional casting processes, fostering advancements in the production of high-quality metal components.
Amogh Vedantha KRISHNA, Tim MALMGREN, Vijeth Venkataram REDDY, Paulo KIEFE, Stellan BRIMALM, Bengt-Göran ROSÉN (Halmstad, Sweden)
00:00 - 00:00 #40124 - A Tribocorrosion Investigation in Food Industry Cleaning Processes.
A Tribocorrosion Investigation in Food Industry Cleaning Processes.

The objective of the presented research is to investigate the relationship between the concept of electrochemical lubrication and the mechanisms of passive film formation encountered during the cleaning process in the food industry. Experimental campaigns were conducted on various types of stainless steels (316L/316L, 316L/uranus45, 316L/Nitronic60, 316L/304, 316L/carbon steel) using a tribometer coupled with a potentiostat in a basic environment. Wear tracks resulting from tribocorrosion experiments were examined using various microscopic and spectroscopic characterization techniques such as SEM, AFM, Raman spectroscopy, XPS, and ToF-SIMS. The electrochemical results, obtained by measuring the open circuit potential, align seamlessly with tribological findings. Specifically, the stability of the friction coefficient is proportional to the potential, and the reduction in the friction coefficient is inversely proportional to the potential. Physico-chemical analysis revealed the morphology and chemical composition of the passive film formed on the surface based on the type of steel under investigation. These findings serve as a foundation to deepen the fundamental understanding of the electrochemical lubrication phenomenon in stainless steels exposed to a basic environment. Tribocorrosion tests aim to replicate industrial cleaning conditions, with the goal of reducing energy consumption related to frictional components and increasing equipment lifespan.
Kaouthar BOUGUERRA (TOURS), Caroline RICHARD, Yan-Ming CHEN, Nadège DUCOMMUN, Pierre-Francois. CAREDY, Alexandre ROMAINE
00:00 - 00:00 #40728 - AI-driven proactive quality control: predictive modelling for surface roughness in milling.
AI-driven proactive quality control: predictive modelling for surface roughness in milling.

The manufacturing sector constitutes approximately 20% of the GDP [1], encompassing a specialized segment known as precision manufacturing. This sector focuses on exacting tolerances in geometry, dimensions, and surface roughness. Among the quality criteria crucial for precision manufacturing is the control of surface roughness in machined parts, traditionally performed outside machine tools [2]. In the context of evolving sustainability standards, the precision manufacturing industry faces the necessity of adapting to new guidelines. Scrapping, the disposal of parts failing to meet quality criteria within the industrial environment, presents a significant challenge. Scrapped parts, deemed substandard, are discarded, resulting in material wastage. This work aims to develop a proactive quality control method with the ultimate objective of correcting machining cutting parameters (e.g., spindle speed, cutting depth, feed rate) in a continuous way during the cutting process. The aim is to prevent the production of parts with out-of-tolerance surface roughness. This approach aligns with the concept of Zero-Defect Manufacturing (ZDF), reflecting a commitment to achieving impeccable quality and minimizing wastage in the precision manufacturing industry. For that, three different non-contact surface roughness sensors from industrial partner STIL/Marposs were implemented on- machine (Fig. 1a) and tested on roughness physical standards to determine the most suitable sensor for the purpose of this work (Fig. 1c). Then, a large batch of surface milling experiments was performed on aluminium (Fig. 1b) to generate a robust database for the AI-modelling investigation. In total, 125 combinations of cutting conditions were applied, and for each machined surface, 6 profiles were measured. With a 3-axis dynamometer, the cutting forces were also acquired during the cutting experiments. By combining data of the input machining parameters, cutting forces, and resulting surface roughness parameters, a database was created. From that, different AI models were constructed with distinct architectures and performances, allowing the assessment of each algorithm's predictive accuracy. The prediction of surface roughness was investigated using two different architectures: Neural Networks (NN) and ensemble methods.
Ricardo KNOBLAUCH (Aix-en-Provence)
00:00 - 00:00 #38854 - Compensation of geometrical errors during application of a confocal sensor system to analyse aerospace structures.
Compensation of geometrical errors during application of a confocal sensor system to analyse aerospace structures.

A non-contact system based on a confocal chromatic sensor was developed to measure the actual geometry after individual machining steps in the machining of components for the aerospace industry, allowing the actual geometry to be compared with the target geometry even in deep cavities of the structure with aspect ratios greater than 20. This technology is necessary in order to apply not only sophisticated machining strategies but also specific monitoring of the machining quality for the precision requirements of components in the aerospace sector. The result of the geometric nominal/actual comparison is the basis for CAM planning of the subsequent machining steps. By coupling the sensor system to a machine tool via standard interfaces (HSK) and carrying out measuring cycles based on modified NC programmes, data can be recorded via a control-connected IoT gateway (EDGE system). In addition to the design of the measuring system and its integration into the machine's ecosystem, a concept for calibrating the measuring system for operation on the machine tool was developed [1]. This is based on pyramidal or conical reference elements (Figure 1). Various aspects of the calibration approach were analysed using a simulation model of the measuring system. As a result, inclination errors and axis deviations of the measuring system can be identified and corrected in the measuring system on the hardware side as well as taken into account on the software side.
Uwe TEICHER (Dresden, Germany)
00:00 - 00:00 #38809 - Effect of the substrate pre-heating temperature on the microstructure and wear behaviour of laser powder bed fusion additive manufactured H13 steel.
Effect of the substrate pre-heating temperature on the microstructure and wear behaviour of laser powder bed fusion additive manufactured H13 steel.

In the process of laser additive manufactured steels, the elevated preheating temperature of the substrate can effectively reduce the temperature gradient, thereby achieving the goal of minimizing residual stress and suppressing the generation of cracks. However, the increment of the preheating temperature typically induces significant changes in the microstructure and mechanical properties. This study delves into the investigation of the microstructure and wear behaviour of laser powder bed fusion (LPBF)processed H13 steel, subjected to preheating temperatures of 200℃ and 500℃, which is considered as one important hot work tool steel with nonnegligible cold cracking tendency during laser processing. Then, the wear behaviour was studied using a reciprocating ball-on-plate tribometer, sliding against the 100Cr6 steel ball at room temperature under various loads (10N, 30N, 50N). The results show that as the preheating temperature increased from 200℃ to 500℃, the volume fraction of retained austenite decreased with improvement in microhardness and wear resistance. Moreover, for the LPBF-processed H13 steel with 200℃ and 500℃ preheating, the coefficient of friction exhibited a continuous decrease with an increase in applied load, while the wear rate initially increased and then decreased. Although there is a similar trend in wear rate and coefficient of friction with changing applied load, the distinct wear mechanisms were observed. For the LPBF-processed H13 steel with 200℃ preheating, under a 10N load, the primary wear mechanisms were adhesive and abrasive wear due to the relatively small tribo-oxide patch formed. As the applied load increased to 30N, the tribo-oxide layer coverage increased, simultaneously, the tribo-oxide layer underwent rupture, resulting in oxidative wear. When the applied load increases to 50N, the density of the tribo-oxide layer increased. After the tribo-oxide layer spalled off, a new oxide film regenerated on the exposed the substrate material, resulting in mid-oxidative wear. The LPBF-processed H13 steel with 500℃ preheating could form a relatively dense tribo-oxide layer to protect the substrate even under a 10N load, which means it exhibited superior oxidizability compared to the sample with 200℃ preheating. The predominant wear mechanisms were mid-oxidative wear and abrasive wear. With an applied load increase to 30N, the formation of the tribo-oxide layer was similar to the situation observed in sample with 200℃ preheating under a load of 50N. When the applied load increased to 50N, the tribo-oxide layer was grounded into oxide particles while undergoing delamination. However, it should be noted that the plastic deformation and strain hardening in the subface region occurred, which could hinder the crack propagation and ensure the outstanding wear performance. Therefore, the higher oxidizability, hardness, and work hardening of LPBF-processed H13 steel wit 500℃ preheating contribute to its superior wear resistance.
Huajing ZONG (chalons-en-champagne), Nan KANG, Zehao QIN, Mohamed EL MANSORI
00:00 - 00:00 #39878 - Effects of Resolution on Finite Element Analysis for Two-Dimensional Rough Surfaces Contact.
Effects of Resolution on Finite Element Analysis for Two-Dimensional Rough Surfaces Contact.

The contact problem of structured surfaces with strong anisotropic properties is attracting increasing attention in the field of modern manufacturing industries. A preferable precise evaluation method accounts the contribution of asperities across the multiscale from nanometres to milometers. However, limited by computing efficiency, a full-dimensional scale finite element simulation on the contact of surfaces is not practical yet. The most common practice is to represent the surface with discrete height maps to calculate the contact behaviour with finite element method (FEM). However, this approach raises the issue that the evaluation results are sensitive to discrete resolution. Currently, quantitative examination is required to determine the adequate lateral resolution of the surface topography represented in finite element meshes. In this paper, the effects of different lateral resolutions on the contact response are investigated on a series of deterministically generated surfaces. A parental surface with ultra-fine spatial resolution is generated by the random process model. Then a set of derivative surfaces are obtained by resampling the parental surface. These surfaces are similar both in height magnification and phase. Compared with fully random surface generation methods, our method possesses the capability to perform a deterministic rough surface contact analysis meanwhile preserving the same power spectral density (PSD) as the original surface, which is crucial for the comparison of the contact response. In this paper, the contact problem of a rough surface compressed by a rigid flat plane is studied using FEM. The simulation results indicate that the averaged pressure increases as the lateral resolution of the deterministic rough surface increases until it converges to a nearly constant value. Thus, a critical lateral resolution applicable to the evolution of rough surface contact is determined when the averaged pressure reaches the constant value. An explicit expression of the pressure-resolution relation is obtained by fitting the simulation results, a case study with a milled surface from NIST database is examined to validate the effectiveness of the expression. The study provides a solution to quantify the 'sufficient fine resolution' of surface topography in finite element simulation for tribological performance evaluation. This will improve the efficiency and accuracy of functionality assessment of engineering surfaces under contact conditions.
Sihe WANG (Xi'an, China), Xuanming LIANG, Weike YUAN, Wenbin ZHONG, Wenhan ZENG, Jiang XIANGQIAN, Gangfeng WANG
00:00 - 00:00 #40059 - Error analysis and compensate method for beam splitter based hybrid structured-light metrology system.
Error analysis and compensate method for beam splitter based hybrid structured-light metrology system.

Hybrid structured-light metrology technique is studied for form measurement of structured surfaces with both reflective and diffuse characters, whose system consists of a fringe projection profilometry (FPP) system and a phase measuring deflectometry (PMD) system. Beam splitter (BS) based compact configuration has been proposed to reduce the system volume of a hybrid structured-light metrology system for improving the portable and in-line measurement ability of the hybrid measurement system, but the using of the BS also introduces error. When conducting measurement with the FPP system, the optical fields of the camera and the projector are required to be overlapped on the sample under test (SUT). At the same time, the light of the camera and the projector will be reflected by the BS and projected onto the system bottom surface. The captured deformed fringe patterns by the camera contain not only the SUT’s form information but also the system bottom surface’s information, which leads to a large measurement error. In this paper, methods are studied to eliminate the BS’ impact on FPP measurement accuracy in a hybrid structured-light metrology system. Influence of the BS is analysed and discussed through imaging model study. Different compensate methods based on the analysis are tested and compared through experiments. A black stage-based technique is developed for a hybrid structured-light metrology system to remove the BS’s affection on measurement accuracy. The camera and projector light reflected by the BS will be blocked by the black stage to reach the system bottom. A portable hybrid structured-light metrology prototype with the BS configuration is developed based on the proposed compensate technique. Experiments have been conducted and verified the effectiveness of the proposed compensate technique by measuring structured composite samples. An in-line measurement experiment using the developed hybrid structured-light metrology prototype illustrates that the proposed techniques can achieve 24.8 µm form accuracy in a form measurement of rough surfaces and 400 nm form accuracy in a form measurement of specular surfaces.
Yongjia XU (Huddersfield, United Kingdom), Feng GAO, Yanling LI, Xiangqian JIANG
00:00 - 00:00 #38808 - Fatigue Behavior of Laser Powder Bed Fusion H13 Tool Steel: Effects of Preheating Temperature and Surface Roughness.
Fatigue Behavior of Laser Powder Bed Fusion H13 Tool Steel: Effects of Preheating Temperature and Surface Roughness.

Laser additive manufacturing (LAM) techniques are widely employed for producing metal components with complex geometries. However, the internal and external surfaces of these components are often challenging to post-machine process. The defects on these surfaces significantly influence the fatigue behavior of the components, necessitating detailed research to discern appropriate processing conditions and performance levels. This study investigates the impact of surface roughness on the mechanical properties and low-cycle fatigue behavior of H13 tool steel manufactured using laser-powder bed fusion (L-PBF) additive manufacturing at different preheating temperatures. Both quasi-static tests and uniaxial tensile-compression fatigue tests were conducted on L-PBF H13 tool steel specimens manufactured vertically (deposition direction parallel to the loading axis) at preheating temperatures of 200°C and 500°C, both in as-built surface conditions and machined to remove the surface conditions. Two non-destructive characterization techniques (micro-CT and interferometer) were employed to determine the relationship between surface contour parameters and surface roughness. The influence of surface roughness on fatigue performance was found to be more significant than the effect of preheating temperature, noticeably reducing the fatigue performance of the components. Surface defects prompted the initiation of fatigue cracks, manifesting as multiple locations of fatigue crack initiation on the surface of the as-built samples. In contrast, machined samples exhibited fatigue cracks originating from only one location. This underscores the decisive role of surface roughness in the fatigue fracture behavior of components. Additionally, specimens deposited at 500°C demonstrated higher fatigue performance compared to those at 200°C, even with the same surface contour. The increased preheating temperature largely released internal residual stresses in the components and transformed the material's microstructure, thus extending the initiation and propagation cycles of fatigue cracks. This work establishes the processing-structure-performance (PSP) relationships of components under different processing conditions, aiming to guide future process parameter optimization and provide insights for the identification strategy of additive manufactured components.
Qin ZEHAO (chalons-en-champagne), Nan KANG, Zong HUAJING, Mohamed EL MANSORI
00:00 - 00:00 #39999 - Functional surface analysis in mechanical engineering.
Functional surface analysis in mechanical engineering.

Improving the quality of manufacturing processes for machine and equipment parts is directly related to with the improvement of inspection methods for manufactured products. This is related to the simultaneous development of the quality control department and the use of increasingly advanced and accurate measuring equipment. One of the most important parameters determining the quality of the product is the structure of the manufactured parts, determined by the type of processing and manufacturing method. An important issue of assessing the condition of the structure is the widely understood surface roughness, which is one of the basic parameters determining the quality of manufactured parts also affecting the functional properties, functional properties, durability or interchangeability of parts in mechanical engineering. Analysis of the literature has shown an increase in interest in issues related to the accuracy and reliability of surface topography measurement. Currently, the most widespread and reliable methods for profile measurements are contact methods, in which the measurement of surface irregularities is carried out using a diamond measuring tip with an opening angle of 60° or 90° and a rounding radius of 2 to 10 m moving over the surface under test at a constant speed over the measuring distance. These are well-established methods, but they are also sensitive to interference factors, including vibration, thermal effects or geometric errors of the measuring tip. Modern quality control requires the use of devices that will return information about the measurement of a selected quantity in a possibly correct manner while maintaining the required accuracy. When the measurement is carried out with standard measuring equipment, solutions are sought to eliminate the influence of interfering factors in an autonomous manner after the basic measurement. Often methods of extensive filtration are used. Surface roughness measurements are classified among the most complex and complicated. Knowing the essence of the surface condition is extremely important from the point of view of machine operation and the durability of mating parts. Taking into account the parameters determining the surface condition, it is possible to influence wear processes, corrosion resistance or fatigue strength. There are also non-contact (optical) techniques for measuring surface roughness. Optical methods use a beam of light reflected from the surface under study for analysis. The light incident on the surface can be white light or light of a certain wavelength or laser light. Optical techniques for measuring surface irregularities use a variety of methods for mapping the structure under study. Often measurements are carried out using several methods implemented in a single device. Each of the listed independent methods, contact or non-contact, carries advantages as well as disadvantages. Combining the advantages of each technique makes it possible to learn about the surface structure in the most correct way. The main objective of the Polish Metrology project entitled: "Functional Analysis of Surfaces in Mechanical Engineering" is the analysis of surface texture, using methods for the extraction and identification of its characteristics that determine their functionality, and the development of measurement methodology in the context of their future operation. Materials with a wide range of applications will be tested, both in terms of utility (wear resistance, hardness or applicability in the food industry) and functional characteristics of the geometric structure of the surface.
Karol GROCHALSKI (Poznań, Poland), Michał WIECZOROWSKI
00:00 - 00:00 #38839 - Implementation of a traceability chain for areal surface texture parameters using a metrological large range AFM.
Implementation of a traceability chain for areal surface texture parameters using a metrological large range AFM.

The ISO standardization framework in the field of calibration, adjustment and performance specification has recently been published. It contains of three different pillars: the metrological characteristics that feature a direct contribution to the measurement uncertainty [1], and are the properties that are subject to a calibration, the corresponding material measures whose geometries can be used to map these characteristics [2] and the calibration routines that are described in the recently published standard ISO 25178-700 [3]. The comprehensive calibration in this context describes the determination of the basic metrological characteristics. The processes associated with the areal traceability and uncertainty propagation however still lack of experience even though a first framework to derive the measurement uncertainty based on the measurement results of the metrological characteristics has been proposed by Leach et al. [4]. Especially the practical implementation of traceability chains containing multiple calibration processes based on the areal surface texture parameters is still subject of research. We describe a case study for the implementation of a traceability chain, using a high-speed metrological large range AFM [5] to measure an additively manufactured type AIR material measure as defined in ISO 25178-70. The material measure is based on a practical engineering surface, features defined values of Sa and Sq and is manufactured using a two-photon polymerization. Starting from the traceability chain of the AFM, the material measure is calibrated and subsequently used to calibrate an optical surface topography measuring instrument which in a case study is chosen as a confocal microscope. The processes of the traceability chain just as well as the determination of the confidence interval of the areal surface texture parameters is described and the industrial application for the calibration of optical surface topography measuring instruments using the areal surface texture parameters is outlined. The suggested calibration routine is easy to implement in practice and allows an efficient uncertainty estimation of the acquisition of areal surface texture parameters.
Matthias EIFLER (Erfurt, Germany), Gaoliang DAI, Julian HERING-STRATEMEIER, Georg VON FREYMANN, Jörg SEEWIG
00:00 - 00:00 #40812 - Preserving Van Gogh's Painterly Heritage: Topographical and Fractal Insights in Authentication.
Preserving Van Gogh's Painterly Heritage: Topographical and Fractal Insights in Authentication.

The search for topographic signatures in an artist's body of work represents an innovative and sophisticated approach, utilizing fractal analysis [1]. This method aims to provide additional indicators to art experts, based on the idea that each artist develops distinctive traits in their painting style, identifiable through unique topographic features. Topographic signatures, in this context, encompass patterns, textures, color choices, brushstrokes, and other specific visual elements that recur in the works of a given artist [2]. By employing fractal analysis, this method explores the complex, self-similar structures present in these features, providing an in-depth understanding of artistic patterns on a detailed scale. Fractal analysis, as a tool, allows for a finer detection of subtle patterns, sometimes escaping the human eye, by assessing geometric similarity at different scales. Algorithms apply this approach to datasets comprising authenticated works by the specific artist, as well as those of other contemporary artists, training the computer model to recognize specific topographic signatures. The objective of this research, reinforced by fractal analysis, is to enhance the artistic attribution process by providing experts with more advanced tools to assess the authenticity of a work of art. By integrating fractal analysis, this method offers a more in-depth approach to exploring artistic features, contributing to a better understanding of an artist's style over time and a more precise validation of the attribution of artworks. In this study, we use a list of paintings unquestionably attributed to Van Gogh to construct our statistical model based on fractal dimension. Once this model is sufficiently robust, we compare it with works by the artist that have been the subject of controversy, such as "Sunset at Montmajour," which was thought to be a forgery for years, and "The Labourers," (Figure 1) which is a proven forgery but has nonetheless cast doubt on the art market.[3,4] To ensure the robustness of the model, we calculated the fractal dimension from different areas, starting with the scale of a brushstroke, then a pattern, and finally over the entire topography.
François BERKMANS (Poznan / Poland)
00:00 - 00:00 #40029 - Surface topography of casting patterns produced using selected additives technologies after the molding process.
Surface topography of casting patterns produced using selected additives technologies after the molding process.

Additive manufacturing technologies especially 3D printing technologies can be used to produce prototypes and functional machine parts [1,2]. Additive technologies can also be used in foundry, e.g., to produce casting patterns or foundry molds [3]. It should be noted that traditional methods of making foundry patterns are time-consuming and have a negative impact on the natural environment. Moreover, the application of 3D printers allows for "immediate" printing of the final part, which significantly improves the procedure of production of casting patterns [4]. The main purpose of the research presented in the paper is to assess the impact of the molding process affect at the surface topography of casting patterns produced using three different types of additive technology, namely: Fused Deposition Modeling (FDM), PolyJet Matrix (PJM) and Selective Laser Sintering (SLS). Casting patterns in the PJM technology were made of FullCure 720 liquid polymer resin, using a thickness of a single layer of material Lt=0.016mm. In the FDM technology, ABS P430 building material and parameter Lt=0.254mm have been used. PA2200 polyamide powder was used to produce samples in SLS technology. The thickness of a single layer of the printing material was Lt=0.1mm and laser energy density was applied: ED = 0.08 J/mm2. Samples for all analyzed technologies were printed using a printing direction equal Pd=0˚. The surface topography was measured with the Talysurf CCI measuring system based on coherence correlation interferometry technology. A measuring objective with X20 magnification was used and surfaces measuring 0.84mm x 0.84mm were analysed. The assessment of the change in the surface topography of casting patterns made using additive technologies was performed quantitatively. The change in the values of surface topography parameters was examined i.e. Sa, Sz and Sq. Analysing the measurement results, it can be seen that the lowest values of the Sa and Sz parameters were obtained for the surfaces of casting patterns produced using the PolyJet Matrix technology. However, the highest values for the tested parameters were obtained for the Selective Laser Sintering technology. Significant disproportions are visible surface topography parameters measured for surfaces printed using various types of additive technologies. For example, the value of the Sa parameter is over nine times higher for models made with SLS technology than for the same models made with PJM technology. Moreover, by analysing the change of the values of Sa parameter as a result of the molding process, it can be concluded that for all the examined additive technologies there was a decrease of the value of the tested parameter. A similar tendency was noted for the Sz parameter, excluding the PJM technology, where a slight increase in the Sz parameter value was observed. However, investigating the value of the Ssk (skewness) parameter, it can be stated that expect the FDM technology for the primary models, positive values of the Ssk parameter were noted, which indicates the surfaces with many single peaks. It should be stated that the molding process for all analysed samples resulted in a reduction of the Ssk parameter. For casting patterns manufactured using FDM and SLS technology, after 100 molding cycles, a surface similar to a plateau can be noted. This indicates some surface wear due to the molding process. However, it can concluded that the surface made using PJM technology is more resistant to wear.
Paweł ZMARZŁY (Kielce, Poland), Tomasz KOZIOR, Damian GOGOLEWSKI
00:00 - 00:00 #40017 - The use of computer microtomography in surface measurements of elements produced by the additive technology MJF.
The use of computer microtomography in surface measurements of elements produced by the additive technology MJF.

MJF, or Multi Jet Fusion, is a state-of-the-art 3D printing technology utilizing powdered plastics for additive manufacturing. This process involves uniformly heating the powdered bed, leading to a sintering phenomenon, allowing for the production of 3D objects. Surface geometry is pivotal for physical objects, influencing their intended purpose. The geometric structure of a surface impacts various physical conditions, such as mechanical strength, coating adhesion, and bacterial distribution. Traditional contact or optical methods were historically sufficient for surface measurement. However, with the advent of additive techniques, limitations surfaced. Real surface profiles deviated from classical functions, introducing the concept of "re-entrants," where a surface profile takes more than one ordinate for a given abscissa. Measuring such surfaces became challenging, especially as contact or optical methods failed to provide information about about non-visible or non-reachable portions of the surface. MJF technology exacerbates this challenge, as it necessitates the removal of powder formulated during printing, leading to the formation of re-entrants covered by powder. Traditional cleaning methods, like sandblasting, may damage and alter the machined surface's geometric character. To address these issues, the proposal suggests using computer microtomography (µCT) for surface data acquisition and evaluation. This measurement method, utilizing X-ray radiation and image reconstruction, offers the unique ability to observe hidden geometric features inaccessible to other devices. µCT's application in evaluating surfaces produced by MJF technology serves a dual purpose. Firstly, it provides information about the surface beneath the remaining powder, a feature unique to this technology. However, post-processing, such as powder removal, introduces surface deformations, necessitating an assessment of how the surface geometry changes. The second aspect involves addressing the re-entrant nature of the surface, posing challenges for reliable measurement with conventional methods. These methods often overlook information about structures hidden by the surface's own geometry. To understand surface changes, samples created with MJF technology were measured before and after post-processing using µCT. The obtained results were compared, offering insights into surface geometry alterations. For comprehensive surface validation and control, a proprietary algorithm was introduced to determine the presence of potential re-entrants. After exporting the surface from µCT measurements and implementing it into the algorithm, the analysis revealed the occurrence and distribution of re-entrants on the surface. This approach aids in deciding whether a specific surface should be measured using µCT or traditional methods. An exemplary result, illustrated in Figure 2, showcases the ratio of the area of individual triangles projected onto the nominal plane to the area of the projection of the entire surface onto the nominal plane which was equal to 2.17. This quantitative representation indicates that 64.18% of the nominal surface is occupied by re-entrants. The proposed approach offers a solution for evaluating MJF-produced surfaces, providing valuable insights for future surface measurement practices.
Patryk MIETLIŃSKI, François BERKMANS (Poznan / Poland), Tomasz BARTKOWIAK, Bartosz GAPIŃSKI, Maxence BIGERELLE, Michał WIECZOROWSKI
00:00 - 00:00 #40983 - Tribological study on solid lubricants at high temperature used in expansion machine.
Tribological study on solid lubricants at high temperature used in expansion machine.

In an internal combustion engine, more than 65% of the energy released by the fuel (gasoline, fuel oil or hydrogen) is rejected in the form of waste heat, 30% in the exhaust gas, and 35% in the engine cooling water. This loss encourages engine manufacturers to improve the energy efficiency of the machine. In order to take advantage of the energy available in the exhaust, different recovery technologies can be considered. The recovery of energy can be done in particular by a Rankine cycle where exhaust gases constitute the hot source of the cycle. The Rankine cycle is promising as several works have shown. The Rankine cycle is made up of a pump, two exchangers and an expander coupled to an electric generator. The heart of the Rankine cycle consists of the choice of the seal of the expander which will ensure the production of mechanical work. Currently, the market for volumetric expansion machines is limited and no expansion machine adapted to energy recovery conditions is available on the market. The development of a new expansion machine operating at high temperature to be able to recover small or medium power from exhaust gas is therefore necessary. In order to equip a scroll type expander with a seal to compress water vapor at high temperature, we carried out a tribological study on different pairs of materials. The seal must ensure both internal sealing function and thus limit losses through internal leaks from the expander. It must also have the lowest possible coefficient of friction in order to reduce friction losses. This joint is in fact stressed by plane friction stresses in an environment under water vapor at temperatures which can reach 250°C. These temperatures make the use of oil and the use of self-lubricating materials complex. The tribological study of the pin/disc type, to determine the pair of materials suitable for defining the joint, focused on the following pairs of materials (graphite/AU4G), Graphite/TiO2) and (Peek/TiO2). The TiO2 Coating was deposited by PVD – CVD evaporation at low temperatures below 450°C. The desired tribological properties are a low coefficient of friction, less than 0.1 and a low wear rate on large temperature range going from ambient temperature up to 250°C for relatively low contact pressures – 0.5 MPa – and sliding speed of the order of 1 to 2 m/s. These operating conditions were determined by complex modeling of the expansion machine by means of which the extreme conditions were simulated. The experiments have been made for a dry and a steam-lubricated contact at several temperatures. It enables us to characterize the frictional torque resistance and seal life required to size the thermal expander. The global discussion is mainly based on the experimental results and on the analysis and observations of wear particles and on worn surfaces.
Hamid ZAIDI (Poitiers - France)

"Monday 27 May"

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08:00 - 09:30

Welcome and Registration


"Monday 27 May"

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09:30 - 09:50

Opening Ceremony


"Monday 27 May"

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09:50 - 10:30

Keynote Presentation 1

09:50 - 10:30 Surface topography and multi-physics functionality of engineering and living surfaces. Hassan ZAHOUANI (Professor) (Keynote Speaker, Ecully Cedex, France)

"Monday 27 May"

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10:30 - 12:30

Surface, Micro and Nano Metrology

Moderator: Kalin MITJAN (Slovenia)
10:30 - 10:50 #38821 - Surface markings for the comparison of topography measurements.
Surface markings for the comparison of topography measurements.

For the evaluation of the surface topography only a small area of the surface in comparison to the whole workpiece is measured. Therefore, markings are needed as reference to relocate the measurement area. For the comparison of different optical or tactile measurement devices, Frühauf et al. manufactured silicon reference samples with etched marks [1]. Another application are before and after measurements to visualize and evaluate the change related to manufacturing processes. Newton et al. used micro-milled slots as relocation landmarks [2]. There is no description if and how they protected those landmarks during manufacturing. Moretti et al. describe algorithms for relocation based on landmarks that can be found both on the original and the manufactured surface [3]. This method can assess partial changes, since the landmarks of the original surface are needed. The relocation under the microscope is done by visual estimation. A proper reference is missing. With this paper new approaches with permanent abrasive markings for those applications are presented. A microscope (Confovis Duo Vario) executes the surface topography measurement. It combines confocal mode, that is used here, and focus variation mode. The surface data is processed with MountainsMap® 7. For the comparison of different optical measurement devices markings with the needle of a height marker are used on a milled surface (Figure 1a and b). In addition, a laser labels the different measurement areas (Figure 1a). The needle lines are used for positioning. They are excluded from the measurement. MountainsMap® provides the function colocalization to superimpose the different data (Figure 1c). Then profiles are extracted and compared to show similar behaviour (Figure 1d). Both devices generate comparable results. The second application are before and after measurements for a blasting process. As markings, Vickers hardness indentations are impressed. A 3D-printed cover protects the area with markings during the manufacturing process (Figure 2a, b and c). After blasting the before and after measurements are superimposed with the use of the indentations. Then profiles are extracted. The profiles show the change created by the impact of the blast media (Figure 2e). The paper will present the comparison by calculating differences for example in volume. As another example, the blasting of additive manufactured surfaces is analysed. The solution for markings depends on the application. The examined markings provide landmarks for proper relocation during the measurement and data evaluation.
Stefanie STÖCKEL (Chemnitz, Germany), Sophie GRÖGER
10:50 - 11:10 #38853 - Exploring Leaf Surface Characteristics for Mitigating Non-Exhaust Particulate Emissions in Transportation.
Exploring Leaf Surface Characteristics for Mitigating Non-Exhaust Particulate Emissions in Transportation.

Transportation-related air pollution, particularly fine particulate matter (PM) from non-exhaust sources, presents significant health and environmental challenges. Roadside vegetation has been recognized for its role in mitigating urban air pollution through the utilization of leaf attributes like surface roughness and trichomes, acting as natural PM filters [1, 2, 3, 4]. Despite potential variations in particle capture among plant species, a comprehensive understanding of the underlying mechanisms is lacking [5]. This study employs a two-phase approach, first by the identification of leaf characteristics that promote the retention of PM generated by tire wear. Subsequently, diverse plant species are chosen based on their attributes, intended to serve as barriers against the dispersion of PM. To simulate exposure to the PM source, a laboratory analytical setup was developed. Four well-adapted leaves from roadside vegetation in France were chosen, representing diverse surfaces with distinct retention mechanisms: Vanhouttei de spirala (1), Euonymus Europaeus (2), Cotoneaster aspressus (3), Cupressus leylandii (4). Using a binocular microscope and 3D optical profilometry, PM capture mechanisms and leaf surface characteristics were analyzed, identifying effective PM removal options among different plant species. This approach provided insights into particle-leaf surface interactions, evaluating size-dependent capture efficiency for effective PM removal. Observations revealed that both leaf topography and particle characteristics significantly influenced particle retention (Figure 1). Specifically, leaf 2 did not retain tire particles in the same manner as soil and aggregate particles, which were effectively captured by leaf 4. The study establishes correlations between leaf micromorphological features and pollutant capture, contributing to the design of effective plant barriers for air decontamination. In conclusion, it underscores the global importance of addressing health impacts resulting from non-exhaust PM emissions, emphasizing the necessity for proactive planning and interdisciplinary collaboration to implement efficient green infrastructure solutions.
Marilia RIBEIRO, Manuela LOPES GENNESSEAUX (Nantes - France), Bogdan MURESAN-PASLARU, Minh-Tan DO, Verônica CASTELO BRANCO
11:10 - 11:30 #38858 - Multiscale curvature characterization for multi-feature anisotropic surfaces.
Multiscale curvature characterization for multi-feature anisotropic surfaces.

Characterizing surface anisotropy is an important aspect of surface metrology considering it can be studied after a manufacturing process as quality control but also to predict and optimize the surface functionality. It helps researchers to understand how surface topography vary in different directions, which is essential for optimizing material performance and ensuring reliability in diverse applications, from industrial to medical. Surface anisotropy, being a parameter that changes with scale, requires a multiscale [1] approach to avoid biasing the results. However, conventional methods using the standard parameters as in ISO 25178-2 [2] are only relevant at a specific scale. The previous advancement in multiscale curvature characterization involved using curvature tensors to determine the most prominent directions for ridges and valleys [3]. That method allowed both quantifying and visualizing surface anisotropy. However, the concept of anisotropy can appear holistic when considering that a surface may exhibit various types of features. For instance, a milled and sandblasted surface or the skin texture, encompass different types of features. Our approach now is to isolate these features to create visualisation of directionalities and geometric characterizations in order to gain a better understanding surface anisotropy. Considering the curvature distribution for a given scale of observation distinctive modes can be considered as candidates for further extraction. For example, a flat surface with bidirectional groove pattern should produce evident peaks in the maximum curvature distribution for a scale related the size of these grooves. That peak should correspond to the inverse value of radii of the grooves. Adding the information about the maximum curvature direction, unidirectional grooves can be further extracted. Using color-coding features of similar morphologies can be visualized on the rendering of surface topography. In this study, we use canvass surfaces painted by both left-handed and right-handed individuals (Fig. 1a). These surfaces exhibit various trends and a strong anisotropy. The primary purpose of this experimentation is to seek relevant parameters to differentiate surface texture with the factor of handedness. This type of morphology exhibits features with a directional tendency. The valleys extracted at the scale of 40× original sampling interval are depicted in Figure 1b. The proposed method should contribute to better understanding the nature, sizes, and direction of surface features.
François BERKMANS (Poznan / Poland), Tomasz BARTKOWIAK, Michal WIECZOROWSKI, Maxence BIGERELLE
11:30 - 11:50 #38860 - Effect of polarisation on the accuracy of surface topography measurement results in coherence scanning interferometry.
Effect of polarisation on the accuracy of surface topography measurement results in coherence scanning interferometry.

In optical metrology, the growing applications of surface texture characterisation contribute to an increasing need for advanced measurement technologies [1]. Coherence scanning interferometry (CSI) is a popular technique in three-dimensional microscopy offering nanometre-level height resolution [2]. Various optical specifications and illumination features influence the accuracy of the surface topography measurement systems. In CSI, the bandwidth of the light source and the numerical aperture of the objective lens change the width of the coherence envelope and/or fringes along the z-axis [3], consequently affecting the accuracy of the measured surface topography. Moreover, the polarisation of the incident light plays an important role in topography measurement using CSI. The polarisation mode of the light can affect how it interacts with surface features. Certain surface structures may exhibit varying reflective or scattering properties based on the polarisation of the incident light. The effect of polarisation on the thickness and optical properties of thin films [4] and the batwing effect due to diffraction from sharp edges on the surface has been studied [5, 6]. The Boundary element method (BEM) is an electromagnetic light field scattering model that provides a rigorous solution to Maxwell’s equations [7]. The BEM model can predict the scattered light from diverse surface geometries, including complex features such as overhangs and undercuts, while accounting for the effect of the polarisation of the incident light [8]. In this study, BEM is used to model CSI (BEM-CSI) with a mean wavelength of 0.6 µm, full-width at half maximum wavelength bandwidth of 0.08 µm and a numerical aperture (NA) of 0.2. The effect of the polarisation of the incident light is investigated on the simulated interference signal corresponding to a silicon sinusoidal profile with a period of 4 µm, peak-to-valley of 0.2 µm and a complex refractive index of 4.289 + 0.0485i (see the red curve in Figure 1) using the BEM-CSI model. Figure 1 shows the cross-sectional view of the interference fringes in the xz-plane obtained by the BEM-CSI model for the (a) transverse electric (TE) and (b) transverse magnetic (TM) modes of the incident light. As depicted in Figure 1, various polarisation modes can introduce a phase shift in the interference pattern leading to errors in reconstructing the surface topography when employing a phase-dependant algorithm, such as Fourier domain analysis (FDA) [9]. Moreover, the visibility of the interference signal depends on the polarisation, thereby influencing the accuracy of the results. Figure 1 (a') and (b') illustrate the reconstructed profiles obtained by the interference pattern of Figure 1 (a) and (b) using the FDA algorithm. Figure 1 clarifies the necessity of choosing an appropriate polarisation to ensure accurate and reliable surface measurement results using a CSI instrument, particularly when dealing with materials or surface features that exhibit polarisation-dependent behaviours. In this study, the effect of polarisation on various surface topographies, and surface materials considering different NAs will be discussed.
Helia HOOSHMAND, Richard LEACH, Samanta PIANO (Nottingham, United Kingdom)
11:50 - 12:10 #40015 - Micro Gear Tolerance Optimization: A Hybrid Approach Combining Bayesian and Genetic Optimization Methods.
Micro Gear Tolerance Optimization: A Hybrid Approach Combining Bayesian and Genetic Optimization Methods.

In precision engineering, particularly in the context of micro gear production, stringent tolerance levels are essential for ensuring optimal functionality. Traditional tolerance design models in this field tend to focus primarily on product value, often overlooking aspects such as product robustness, which presents challenges in maintaining a balance between manufacturing precision and cost efficiency. This study proposes a hybrid optimization method that combines the predictive strengths of Bayesian techniques with the comprehensive search capabilities of genetic algorithms. This method is designed to address both precision and cost-effectiveness in micro gear manufacturing. The research methodology employed integrates statistical analysis with algorithmic modeling. Bayesian methods are utilized for forecasting and adjusting tolerance levels, using historical data and probabilistic models to enhance manufacturing accuracy. Concurrently, genetic algorithms are applied to explore a range of design parameters, aiming to identify optimal tolerance settings. This approach is known for its effectiveness in tackling complex optimization problems. The combination of these methods allows for an extensive exploration of potential solutions, seeking to achieve an equilibrium between precision and cost. Early results from this study suggest an improvement in tolerance optimization compared to traditional single-method approaches. The validation of this approach was conducted on a dataset comprising real-world micro gear manufacturing scenarios. The findings indicate that this method is applicable and effective in real-world manufacturing settings, offering a feasible approach to balancing precision and cost in micro gear production.
Jin JIN (Chengdu, China), Yuanping XU, Hongsheng FU, Yue ZHU, Tukun LI, Chao KONG, Dan TANG, Jian HUANG

"Monday 27 May"

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12:30 - 13:30

Lunch Break


"Monday 27 May"

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13:30 - 14:10

Keynote Presentation 2

13:30 - 14:10 How to accelerate Green Hydrogen Project: Some metrological challenges. Olivier MACHET (dsds) (Keynote Speaker, dsd, France)

"Monday 27 May"

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14:10 - 15:50

Metrology for smart manufacturing

Moderator: Cosimi CORLETO (STIL) (Aix-en-Provence Cedex 3, France)
14:10 - 14:30 #40676 - AI-Driven tribological approach applied to on- machine surface roughness prediction.
AI-Driven tribological approach applied to on- machine surface roughness prediction.

In the manufacturing industry, metrology assumes a critical role in affirming the quality of end products. [1] In cases where specific precision components fail to meet quality specifications, they are often scrapped, posing sustainability challenges for the manufacturing process. With the help of AI and smart sensors, we can move towards zero-defect manufacturing with an explainable approach. [2,3] Turn-mill machining center DMG is used to perform the cutting experiments. Apart from the machining parameters, a 3-axis dynamometer is used to record the cutting force. A chromatic confocal sensor was used to record the roughness as ground truth for on-machine measurement of roughness. 200 different cutting conditions were used to design experiments consisting of up and down milling. Instead of implicit feature extraction procedure with deep learning-based models, the work proposes a force lobe- based approach by creating windows within the force signals. Further different statistical features such as mean, standard deviation, skewness, kurtosis, crest factor etc were extracted from these windowed signals. Furtsssher these features were given as input to Machine learning model. Multiple ML models were tested but Random Forest was chosen as the base model because of its implicit explainability and overfitting handling criteria. Further, by experimenting with combinations across predefined parameter grids, grid search is used to methodically investigate and adjust hyperparameters for machine learning models, guaranteeing optimal performance. A regression model was developed to predict the roughness and a classification model was used to predict whether the signals belong to the category of Up or down milling based on the cutting force signals. The results show a strong correlation between the lobe-based features with the final output of prediction of surface roughness. This is validated from the waterfall graph showing the feature importance for the prediction models. This work is also the starting point of a proactive quality control model focusing on the process monitoring part.
Sourish GHOSH (Aix-en-Provence)
14:30 - 14:50 #40286 - Advanced Metrology for Smart Manufacturing: Integrating Optical Fiber and ETDR Technologies for High-Temperature Monitoring.
Advanced Metrology for Smart Manufacturing: Integrating Optical Fiber and ETDR Technologies for High-Temperature Monitoring.

In the domain of smart manufacturing, precise temperature monitoring is crucial, particularly for assets like arch, kiln, or arc furnaces in industries such as foundry and glass production. Traditional methods like thermocouples offer only sporadic and isolated measurements. To address this limitation, recent advancements in Optical Time Domain Reflectometry (OTDR) have enabled distributed temperature measurements. However, the applicability of optical fibers is constrained to temperatures below 700°C, due to durability concerns over extended industrial usage. This paper presents a comprehensive study on the deployment of Optical Fiber and Electrical Time Domain Reflectometry (ETDR) technologies, tailored for high-temperature monitoring in industrial environments. The focus is on the development of robust sensors capable of enduring extreme conditions, particularly temperatures above 700°C, where OTDR sensors reach their limits. For temperatures below 700°C, the utilization of optical fibers presents a viable solution. The study elaborates on the advancements in optical fiber technology, particularly in enhancing their temperature endurance and measurement accuracy, making them suitable for a wide range of industrial applications. In the context of higher temperatures, ETDR sensors emerge as a promising alternative. The study introduces an innovative ETDR-based sensor system, capable of enduring and accurately measuring temperatures beyond the threshold of optical fibers. This system employs a high-frequency electro-magnetic signal within a transmission line composed of materials specifically chosen for high temperature and durability. The backscattered signal analysis from these ETDR sensors provides a distributed and continuous temperature profile along the sensor line. A significant portion of the study is dedicated to material selection and aging properties to optimize the response of ETDR sensors to high temperatures. Various materials, including alumina as a dielectric and different metals as conductors, are investigated for their suitability in ETDR systems. The paper discusses the experimental and modeling approaches employed to identify the most efficient material combinations and sensor geometries, considering factors like permittivity, resistivity, permeability, and environmental influences such as temperature, humidity, and mechanical strain. The paper aims to promote the development of these new technologies, offering a pathway towards more efficient and reliable temperature monitoring in smart manufacturing settings. By integrating optical fiber and ETDR technologies, the study paves the way for enhanced monitoring capabilities, contributing to the safety, efficiency, and longevity of various industrial processes. Main References [1] F.-K. Chang, Structural health monitoring 2000. CRC Press, 1999. [2] J. A. Stastny, C. A. Rogers, and C. Liang, "Distributed electrical time domain reflectometry (ETDR) structural sensors: design models and proof-of-concept experiments," in Smart Structures and Materials 1993: Smart Sensing, Processing, and Instrumentation, 1993, vol. 1918: International Society for Optics and Photonics, pp. 366-376. [3] R. H. Cole, "Time domain reflectometry," Annual review of physical chemistry, vol. 28, no. 1, pp. 283-300, 1977. [4] S. B. Jones, J. M. Wraith, and D. Or, "Time domain reflectometry measurement principles and applications," Hydrological processes, vol. 16, no. 1, pp. 141-153, 2002. [5] B. M. Lee, K. J. Loh, and F. L. di Scalea, "Distributed Strain Sensing Using Electrical Time Domain Reflectometry With Nanocomposites," IEEE Sensors Journal, vol. 18, no. 23, pp. 9515-9525, 2018. [6] S. Sun et al., "A novel TDR-based coaxial cable sensor for crack/strain sensing in reinforced concrete structures," IEEE Transactions on Instrumentation and Measurement, vol. 58, no. 8, pp. 2714 2725, 2009. [7] T. Wei, S. Wu, J. Huang, H. Xiao, and J. Fan, "Coaxial cable Bragg grating," Applied Physics Letters, vol. 99, no. 11, p. 113517, 2011. [8] Z. Zhou, T. Jiao, P. Zhao, J. Liu, and H. Xiao, "Development of a distributed crack sensor using coaxial cable," Sensors, vol. 16, no. 8, p. 1198, 2016.
Mickael BOINET (Cavaillon)
14:50 - 15:10 #39005 - A novel semiempirical model for predicting bulge generation in femtosecond laser ablation processes.
A novel semiempirical model for predicting bulge generation in femtosecond laser ablation processes.

Femtosecond lasers offer significant advantage in precision manufacturing due to the ability to create surface textures with a minimal heat affected zone avoiding undesirable bulges that can alter the functionality of the surface in applications such as tribology [1]. The selection of optimal parameters for achieving bulge free textures remains a complex task based on trial-and-error approaches. Current heat accumulation prediction models assume that the unused ablation energy remains in the material as residual heat, leading to thermal damage prediction [2]. Nevertheless, these models do not predict bulge generation. This study presents a new semiempirical model for bulge generation prediction in multi-shot dimple and line ablation. The model is based on the mean energy delivered per unit area throughout the ablation process, i.e. the accumulated fluence, and validated through the measurement of the generated bulges. A femtosecond laser was used to ablate multi-shot dimples and lines with various process parameters combinations. Sensofar 3D optical profiler employing confocal technology with EPI100X objective was used to measure the generated geometry, and bulge’s mean and maximum height and volume were characterized (see Figure 1). After analysing the evolution of the mean and maximum height and volume of the bulges with the accumulated fluence, a relationship with the bulge’s volume was found as observed in Figure 2 (a). Results indicated two regimes: (i) absence of bulge generation and (ii) bulge generation, with logarithmic increase of the normalized volume as the accumulated fluence rise (see Figure 2 (b)). This trend was consistent for both dimples and lines with limits for bulge formation calculated at 31.48 ± 8.8 J/cm2 and 30.67 ± 13.7 J/cm2 respectively. The study concludes that accumulated fluence serves as a viable metric for establishing a limit for bulge generation. Incorporating the limit of accumulated fluence into existing prediction models for laser ablation profiles represents an improvement as it guarantees the selection of process parameters that create textures with bulge-free edges without the need of trial and error.
Ainhoa GUINEA (Mondragon, Spain), Andrea AGINAGALDE, Joseba MENDIGUREN, Iñigo LLAVORI, Wilson TATO, Eneko SAENZ DE ARGANDOÑA, Alaitz ZABALA
15:10 - 15:30 #40036 - Progress toward compact spectrometry realised via metasurfaces.
Progress toward compact spectrometry realised via metasurfaces.

To optimally deploy optical instrumentation more widely within manufacturing chains and aid a move towards Industry 4.0, sensors need to be developed in a form more suitable for integration [1]. Current optical instrumentation is often too bulky and heavy to perform in-process and on-machine measurements within manufacturing systems without interfering with ongoing processes. One reason why current instrumentation is too large is the number and size of the optical components, such as glass lenses, utilised in their construction. A reduction in the size or number of these elements would allow significantly more compact optical instruments to be created. One instrument we have particular interest in is a Single-shot Dispersive Profile Interferometer (SDPI) [2], which is designed to take on-machine measurements of the surfaces of moving substrates in roll-to-roll processes for printed electronics. In an SDPI, light from the image of a line on the measurand surface and that from a reference beam is combined before being separated out by wavelength in a direction perpendicular to the measurement line, producing a spectrum for each point along it. The variation of intensity within the spectrum from each point encodes the height of the surface at that location, allowing a profile to be determined from a single image. The determination of the spectrum at each point along the line is currently carried out using a traditional form of spectrometer, one that requires multiple components to separate the different wavelengths of light and focus them onto different regions on an areal CCD/CMOS detector. However, in this form the spectrometer takes up a significant portion of the size of the overall instrument which limits it potential for integration. Photonic metasurfaces are an emerging technology which allows the manipulation of light without the bulk of traditional optical elements, with elements having a thickness on the order of the wavelength of light. Furthermore, they can be designed to perform multiple functions simultaneously, reducing the need for the multiple optical elements required in many applications [3]. Here we present our work towards developing a single metasurface element that combines focussing and wavelength separation functions, allowing a spectrometer to be formed with just the addition of a detector [4]. This approach can significantly reduce the size of the spectrometer, lowering the number of elements that need to be aligned (and maintained in alignment). The metasurfaces utilised here uses the truncated waveguide approach and consists of an array of GaN nanopillars fabricated on an Al_2 O_3 substrate. By varying the form of the pillars across the surface, the phase delay imparted on the light can be changed by up to 2π radians, and in this way incident wavefronts can be reshaped arbitrarily as they pass through. The spectrometer harnesses the strong chromatic aberration that is present with basic metalenses of this form in order to angularly separate the light. The metasurface is designed to take light from a specific point, and at a specific wavelength, on the object side of the metasurface and focus it to a point on the detector side. The chromatic aberration present leads to a shift of the focal point on the detector side for other wavelengths (see figure 1). A shift of the point source in the y-direction corresponds to a shift where the spectra is formed. In this way the spectrometer required by the SDPI is formed. Here we will present details on the design, fabrication, and characterisation of the metasurface-based spectrometer, which is a crucial stepping stone to developing a more compact SDPI instrument in the near future.
Andrew HENNING, Joseph KENDRICK (Huddersfield, United Kingdom), Haydn MARTIN, James WILLIAMSON, Dawei TANG, Nityanand SHARMA, Xiang (Jane) JIANG
15:30 - 15:50 #38747 - A novel data fusion pipeline for point cloud registration.
A novel data fusion pipeline for point cloud registration.

In this work, we propose a data fusion pipeline for registering two point clouds that have a distinct disparity in the size and point density: one point cloud is large and sparse, while the other is small and dense. The small and dense point cloud represents the surface texture details of a region located within the large and sparse point cloud. The motivation behind the data fusion pipeline proposed in this work is that most of the latest data fusion algorithms are only applicable to point clouds with similar sizes and point densities. In this algorithmic pipeline, firstly, the large and sparse point cloud is defined as the reference and it is segmented into subsections (“sub-clouds”), each of which is sized identically to the small and dense point cloud. Then, the distances between points and the plane formed by two of the main axes (principal component analysis – PCA) are calculated and plotted into histograms for the small and dense point clouds and each sub-cloud. Sub-clouds showing similar histograms to the small point cloud’s histogram are selected as candidates. In the next step, the angles between local normal vectors and the PCA-plane are calculated and plotted into histograms for the small and dense point cloud and all candidate sub-clouds. The sub-cloud generating the most similar histogram to the small point cloud’s histogram is determined as the best matching. The small point cloud is then transferred into the coordinate frame of the large point cloud and translated to the target sub-cloud’s location. The next step is to determine the correct orientation of the small point cloud: the small point cloud is rotated around 360° in 10° intervals and voxelised into (10 × 10) voxels on the x-y plane and five layers along the z-axis (i.e. 500 voxels in total for each point cloud). The target sub-cloud is voxelised simultaneously with the same configuration. The percentage of points falling in each voxel (i.e. the percentage relative to the total number of points in the processed point cloud) is then calculated. The voxels of the small point clouds and each candidate sub-clouds are compared : if two corresponding voxels for these two point clouds have similar percentages, this pair is defined as a good match. Finally, the orientation of the small point cloud which gives the largest number of matched voxel pairs is determined as the correct orientation for registration. The proposed pipeline has been tested on synthetic three-dimensional models characterised by artificial engineered surfaces.
Zhongyi Michael ZHANG (Nottingham, United Kingdom), Adam THOMPSON, Sofia CATALUCCI, Samanta PIANO

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15:50 - 16:10

Coffee Break


"Monday 27 May"

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16:10 - 17:50

Measurement, Instrumentation & Characterization in Metrology

Moderator: Mustapha EL BOUCHOUAFI (General Manager ZEISS IQR) (Rueil Malmaison, France)
16:10 - 16:30 #40313 - Characterization of the tactile perception of textured materials for packaging.
Characterization of the tactile perception of textured materials for packaging.

The Textures are becoming more and more key in the perceived value of our packaging, in the adequation between formula and packaging and for our consumers experience. Our objectives in terms of sustainability and recyclability lead us to reduce the diversity of type of materials that we can use but also we need to increase the diversity of sensorial tactile textures and consumer experience.The diversity of textures achievable on a packaging is also a large territory of technical improvements. All these needs create the necessity of having an objective and quantitative way to characterize and evaluate a texture and its corresponding tactile perception. This work aims to develop new knowledge and establish a multisensory database (roughness, touch) to facilitate the substitution of conventional plastic packaging solutions with more environmentally friendly alternatives, while reducing post-processing steps (varnishes, paints) that negatively impact the recyclability of products. We conducted a cross-study on the roughness and touch of materials used in packaging manufacturing. The goal was to establish a classification of the tactile sensorial properties of the samples. Initially, we analyzed the surface roughness with a multi-scale wavelet analysis method [1]. This method allows quantifying each wavelength family composing the surfacewith the roughness criterion SMa, representing the average value of the signal amplitude for a given wavelength. The results are presented in the form of an SMa roughness criterion spectrum, ranging from small to large wavelengths, forming a unique and multispectral signature of the surface topography signal. Secondly, we measured the tactile sensorial vibrations of the samples using an electonical finger. Thirdlyl, we measured the tactile sensorial properties of the samples using an electonical finger and TouchFinger [2], an innovative device simulating an augmented human finger. When we touch the surface of an object with our index finger, the friction of the finger's skin on the surface vibrates the mechanoreceptors located in the finger pulp [3]. The vibratory response is then instantly converted into an electrical signal, transmitted via the central nervous system to the brain, which interprets this information as the sensory quality of the surface. Like the human finger, the device is equipped with vibration sensors and a force measurement sensor. It comes in the form of a half-ring that slips onto the tip of the index finger. When touching a surface, the vibrations and the force recorded by the device are transformed into tactile quality parameters for each of the four mechanoreceptors: Pacinian, Ruffini, Merkel, and Meissner [4][5]. The experimental protocol was conducted on a diversity of materials : cardboard, glass, aluminium, PET, PP, recycled PP, recycled PET; and a diversity of Textures achieved by mechanical or chemical treatment, spraying deposit and laser engraving . All samples were measured in topography with a white light confocal device, then characterized with the SMa parameter by the 2D continuous wavelet method. For the evaluation of the touch of the samples, a panel of 10 people aged 22 to 25 years was formed. Measurements were performed with the TouchFinger device in a temperature-controlled room (21°C +/- 2°C) and humidity (50% +/- 5%). For each surface, the panelists performed three successive touches and replicated the measurement three times. The vibratory signals obtained were analyzed by a frequency decomposition method to calculate the mean vibratory level (La parameter (dB)) in each of the mechanoreceptor frequency bands. The average values obtained of the La (dB) parameter for each of the mechanoreceptors were analyzed in correlation with the surface topography parameters. The results obtained allow establishing a database of the tactile quality of reference samples based on their material and texture.
Hassan ZAHOUANI (Ecully Cedex), Roberto VARGIOLU, Nicolas DURU, Corentin PERRAIS, Gustavo LUENGO, Olivier DELATAULADE
16:30 - 16:50 #38862 - Detection and analysis of re-entrant features created on additively manufactured surfaces.
Detection and analysis of re-entrant features created on additively manufactured surfaces.

The aim of this research is to detect re-entrant features which are a signature of the additive manufacturing process that involve sintering or melting of metal or plastic powders. Conventional surface measurement techniques such as profilometry or optical microscopy consider measured surface as a function z=z(x,y), meaning that for any given location on the surface (x, y), there is only one unique height (z). These techniques work well for surfaces whose shape can be locally approximated using a plane, cylinder, or ellipsoid, or for surfaces considered at a large scale of observation. For freeform surfaces with complex geometry, consisting of pores, voids, cracks, or overhangs being present at the microscale, and resulting from incompletely sintered or melted powder or the turbulent interaction of a laser energy beam, these so-called re-entrant features are impossible to register due to the physical limitations of optical and contact methods[1]. With the development of metrological high-resolution X-ray microcomputed tomography, it has become possible to study regions of surfaces invisible to other techniques. However, due to the implicit representation of the surface, a change in the approach to its parametric and non-parametric description, especially present in ISO or ASME standards, is necessary [2-3]. The subject of this study are parts produced using Selective Laser Melting technology. The input material Ti-6AL-4V powder with a grain size between 15 µm and 45 µm. The geometry of the samples was a quarter cylinder with a radius of 5 mm and a height of 25 mm. The samples were produced using EOS M290 machine. To achieve a large diversity of surface morphology, process parameters were varied: laser power (between 107 and 267 W) and scanning speed (between 250 mm/s and 1000 mm/s). The samples were not subjected to any additional finishing processing. The surface topography was registered using Baker Hughes/General Electric v|tome|x s240 microCT scanner, obtaining a voxel size of 5.5 µm. On each of the reconstructed 3D models of the sample surfaces, every 0.1 mm, 20 roughness profiles along the build-up direction were extracted. Each profile was averaged using a B-spline curve, assuming it as the local form. For each point of the original profile, its projection onto the form profile was determined, and then it was checked whether the coordinates of the subsequent projected points increased in the same direction as the coordinates of the form profile. If the local direction of increase changes, it means that a local re-entrant feature has been detected. A large number of such features may indicate inappropriately selected parameters of the technological process or disqualify other measurement techniques for credible registration of the surface topography. On the other hand, a small number of re-entrant features may suggest that an alternative measurement using profilometry or optical microscopy adequately reproduces the given SGP. The frequency of occurrence of these features, in the context of laser beam power and scanning speed, is the subject of analysis in this article. Exemplary results of detected re-entrant features and the effect of technological parameters on the frequency of their occurrence is shown in Figure 1.
Tomasz BARTKOWIAK (Poznan, Poland)
16:50 - 17:10 #39884 - Bio-engineering of perfume interaction with human skin and olfactory sensoriality.
Bio-engineering of perfume interaction with human skin and olfactory sensoriality.

Perfume is a complex composition of odorants and solvents, with a variety of physico-chemical characteristics such as volatility, molecular weight and vapor pressure, in addition to their unique olfactory properties. When perfume is applied to the skin, only part of its components is perceptible to the human sense of smell, and this perception depends on many factors such as the physico-chemical properties of each molecule, the interactions between the ingredients in the perfume formula and the surface to which it is applied, such as the skin. In addition, external factors can influence the evaporation of odorants, which can lead to significant variations in concentration profiles, even for similar doses. Given that the sensory performance of fragranced products is crucial, it is of great interest to understand how the skin can influence the behaviour of a fragrance. Consequently, methods are needed to characterize the interaction of fragrance with the human skin surface. Raman spectroscopy is proving to be a fast, non-invasive analytical technique, ideal for investigating the molecular mechanisms involved in the interactions between different types of fragrance and the human skin. In this study, we examined the performance of different fragrances on ex vivo skin as a function of time using Raman spectroscopy. We discuss the most important bands observed in the Raman spectra, and also present results concerning the characterization of different skin types, including proteins, sebum content and hydration level. Finally, we have classified these skin types according to these different parameters.
17:10 - 17:30 #40001 - Deterministic form-position deflectometric measurement of transparent optics.
Deterministic form-position deflectometric measurement of transparent optics.

Deflectometry is a powerful measuring technique of complex optical surfaces. It has extremely high sensitivity to surface slopes, but the in most cases, the measurement accuracy can only achieve a level of microns. The main limiting factors of the measurement accuracy are investigated. A flexible camera model and an automatic calibration method are developed. The geometrical pose and location of the workpiece are solved by minimizing the re-projection error of ray-tracing, and an automatic positioning method is proposed by combining the Gaussian process regression.
Xiangchao ZHANG (Shanghai, China)
17:30 - 17:50 #40304 - Ecological niche partitioning revealed among Theropod dinosaurs through Dental Microwear Texture Analysis.
Ecological niche partitioning revealed among Theropod dinosaurs through Dental Microwear Texture Analysis.

Most predatory theropod dinosaurs, excluding spinosaurs, have long been thought to retain the plesiomorphic dinosaurian condition of carnivory. The presence of numerous, similar sympatric medium- to large-bodied predatory taxa in localities such as the Bahariya, Huincul and Morrison formations therefore raise questions regarding ecosystem structure. Spinosaurs are known for piscivory and possess adaptations for subaqueous feeding and locomotion, whereas their sister clade, megalosaurids have generally been considered to include only terrestrial predators. However, increasing evidence suggests that megalosaurids, especially European taxa, had a preference for feeding in mesic and aquatic environments. Establishing dinosaurian diets have often relied on tooth morphology or stomach contents, both which have limitations, such as convergent morphology in the case of the former or capturing fall-back foods rather than usual diet in the case of the latter. Moreover, tooth morphology usually recognises broad dietary guilds, such as herbivory or carnivory, only. Recent work on extant and extinct archosaurs and lepidosaurs have shown that dietary guilds can be determined for fossil taxa more precisely, including categories like hard or soft invertebrate diets, carnivory and piscivory, among others, by using Dental Microwear Texture Analysis (DMTA)1,2,3. Using a confocal microscopy and dental moulds, the 3D surface textures of a theropod tooth sample were analysed at 100x magnification using common parameters from the literature 1,2 . Preliminary results suggest that predatory theropod diets were more diverse than previously thought, with megalosaurids showing evidence for piscivory and tyrannosauroids (the clade that includes Tyrannosaurus rex) potentially exhibiting non-carnivory in their diets. Consequently, niche partitioning might have occurred between sympatric theropod taxa due to specialisations in their diets that prevented direct competition. Furthermore, application of DMTA along the tooth rows within individual theropod jaws might allow the method of prey acquisition to be determined based on serial variation in the microwear patterns of the teeth with the potential to test biomechanical models.
Cassius MORRISON (London, United Kingdom), Philip MANNION, Laura PORRO, Liam BLUNT, Paul BILLS, Paul BARRETT
Tuesday 28 May

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08:00 - 08:40

Keynote Presentation 3

08:00 - 08:40 Metrological structure of Bio-locomotor surfaces: the role of surface design in achieving economy of effort. Hisman Amed ABDEL AAL (Keynote Speaker, USA)

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D2-Session 1
08:40 - 10:20

Functional Applications

Moderator: François BLATEYRON (VP, Research & Metrology) (Besançon, France)
08:40 - 09:00 #38703 - Experimental identification of the relevant scale for the machinability analysis of biocomposites.
Experimental identification of the relevant scale for the machinability analysis of biocomposites.

The machining of biocomposites remains among the important challenges that face the economic world for the development of these eco-friendly materials in order to achieve their final transformation and meet industrial standards. The main issues of biocomposite machining result from the multiscale cellulosic structure of the natural plant fibrous reinforcement that induces high fiber deformation, high sensitivity to process parameters, and high dependence on environmental conditions (humidity and temperature) during cutting operations. Moreover, plant fibrous reinforcements show in general a random structure that is intimately related to the random distribution of the technical fiber size. Indeed, when observing a biocomposite surface made of unidirectional flax fibers and polylactic-acid (PLA) matrix, it can be noticed from Figure 1 that the fibrous reinforcement can be in the form of separated elementary fibers (from 10 µm to 20 µm in diameter) or technical fibers that are a bundle of several elementary fibers. These technical fibers have a variable diameter (depending on the number of elementary fibers) that ranges from 50 µm to 150 µm. In some cases, the plant reinforcement is in the form of fiber yarns that can reach around 1mm in diameter. Therefore, the plant fibrous reinforcement is present at different scale levels in the biocomposite structure with different mechanical properties at each of these scales. Surface characterization of biocomposites for machining analysis should then consider this multiscale configuration in order to discriminate the effect of each material or process parameter. In this paper, the machined surfaces of flax/PLA biocomposites performed with the milling process have been analyzed using a white light interferometer at different scales as shown in Figure 2. Energetic analysis and SEM observations of the machined surfaces have been performed to compare with the results of the multiscale topographic measurements. At each measurement scale, the 3D mean arithmetic roughness parameter (Sa) has been calculated to assess the effect of process parameters. Results demonstrate the significant impact of the analysis scale on the topographic behavior of the machined surfaces in the function of the process parameters. The variation of the analysis scale allows the involvement or the non-involvement of several machining-induced mechanisms such as single fiber deformation, fiber bundle deformation, matrix plowing, interface damages, and milling-induced waviness. Consequently, the discrimination of the process parameter effect (that is responsible for each machining-induced mechanism) is not similar when varying the topographic measurement scale. By comparing with the microscopic SEM observations and the energetic analysis, the results of this work lead to identifying the relevant analysis scale for an efficient machinability qualification of unidirectional flax fibers reinforced PLA biocomposites.
Faissal CHEGDANI (Paris), Mohamed EL MANSORI
09:00 - 09:20 #38807 - Relationship between road surface macrotexture and water spray – Application to the estimation of road wetness.
Relationship between road surface macrotexture and water spray – Application to the estimation of road wetness.

Water spray due to a tire rolling on a wet road surface has been studied to mitigate the reduced visibility [1, 2] or, in recent years, estimate the road surface wetness [3, 4, 5]. Previous research, conducted mainly with trucks [1, 2], has enabled to understand the effect of the vehicle speed and the tire tread sculpture on the amount of water spray. Despite the fact that the road surface is inseparable from the tire in a contact study, less is known about the link between the road surface texture and water spray. This paper aims at responding to this gap. The study involves a passenger car and water spray is characterized by the vibration of wheel arch liners due to impacts of water droplets. The instrumentation of the car, consisting of equipping the front wheel arch with accelerometers, is presented. Tests are performed on six road surfaces, representing various textures, and at different vehicle speeds and water depths simulating the road wetness during and after a precipitation. 3D topographical maps (squares with 100 mm sides) of the test surfaces are measured by means of a portable device. Signals recorded by the accelerometers are filtered and processed. The surface topography is analyzed using the MountainsMap software from which geometrical and functional parameters are calculated. Results, showing that the acceleration amplitude increases with increasing vehicle speeds and increasing water depths on the road surface (Fig. 1), are consistent with previous studies. They also highlight the fact that current parameters used in the road field to characterize the road surface texture (the so-called Mean Texture Depth and Mean Profile Depth) are not relevant enough to explain the observed difference between the test surfaces (Fig. 2). Analysis of parameters characterizing the orientation of the texture and the void distribution better reflect the role of road surface texture with respect to water evacuation (by drainage or squeezing) from the tire-road contact area. With this new finding, it is possible to establish a relationship between water spray and influencing factors (water depth, vehicle speed, road surface texture). Discussions are made in terms of application of this relationship to an on-board estimation of the tire-road friction to improve the vehicle stability and the driver safety.
Minh-Tan DO (Nantes), Ebrahim RIAHI, Wiyao EDJEOU, Manuela GENNESSEAUX, Veronique CEREZO
09:20 - 09:40 #38835 - Surface metrology for ensuring perceived quality – a study on injection moulded plastic parts.
Surface metrology for ensuring perceived quality – a study on injection moulded plastic parts.

Plastic components are produced in large volumes in fast and highly automated production lines. However, the injection moulds are individually manufactured and manually polished to reach the required surface finish to produce highly glossy plastic components with surface roughness levels in the nm-range. Today’s ever-increasing demands for high quality products, shorter lead times and reduced costs, push manufacturers to find alternative finishing solutions. The inspection and validation of the mould- and component surfaces are based on master plaques developed for each specific purpose. But there is a need to make these evaluations more objective, i.e. to quantify the perceived quality of the plastic components to specify standardised and measurable parameters for the mould surface, since the moulds are manufactured by different suppliers using various types of manufacturing procedures leading to varying surface structures. This study was based on nine different part geometries, nine colours and five types of polymers in different combinations, in total 180 samples, and nine mould surfaces. The components were visually inspected and graded at the company based on an internal evaluation procedure based on the total appearance of the component. All component- and mould surfaces were measured with a coherence scanning interferometer using a 10x Mirau interferometer objective giving a measurement area of 0.86mm x 0.86 mm. A measurement strategy was developed for quality control of components, recommending measurements ’every other mm’ to catch local surface variations as milling marks or holes. Perceived quality was related to surface texture parameters, separated for longer and shorter wavelengths. However, the mould surface was replicated to a varying degree by the different plastic materials, and in some cases other features (as small holes or scratches) rather than the mould surface texture constituted the dominant surface structure of the components, see figure 1. Defects were divided into four classes, circular (in- & outwardly, i.e. holes and peaks), and elongated (in- & outwardly, i.e. scratches and ridges). Yet, visual evaluations are not consistent but are ‘adjusted’ to the context (as part type and placement according to other components). The long-term goal is to develop a surface metrology strategy for production of injection moulded plastic parts, including the surface quality of moulds.
Rebeggiani SABINA (Halmstad, Sweden), Reddy VIJETH
09:40 - 10:00 #38855 - Surface topography and control of sawn wood.
Surface topography and control of sawn wood.

One important key factor for smart and sustainable production is more intensive use of smart and customized metrology systems. The wood industry has not yet benefited from this technology, but a combination of “intelligent monitoring and multi-objective optimization approaches should pave the way for controlling the sawing process so higher surface quality and cost-efficient machining is achieved” [1]. Advanced techniques for, for example, saw pattern optimization, timber grading and traceability are commercially available, but there is a lack of methods for measuring and characterizing sawn wood surfaces to provide feedback on tool wear and tool stability, as well as to provide a framework for the industry to define functional surface quality of wood products. Over-compensation of cutting parameters is one example where a better understanding of resulting wood topography combined with smart online metrology systems could contribute to a more sustainable production - a production increase corresponding to 75,000 m3 sawn timber per mm reduced saw blade thickness is realistic, which would be further improved if dimensional stability could be increased [2]. This study includes 36 boards (spruce trees) taken from the production line in a sawmill (circular sawing); 12 boards just after a saw blade shift, 12 boards mid-time, and 12 boards before a blade shift (i.e. sawn with a worn blade). All boards were scanned at site with board scanners (accuracy on the mm level), as well as with a laser scanning system (micro-epsilon scanCONTROL 2900-100 with a quoted resolution of 1280 pixels/profile) giving an accuracy on the um level. The areal surface parameters defined in ISO 25178-2 [3] are used to characterize the measured surface topography, especially the surface parameters root mean square height (Sq), reduced peak height (Spk) and reduced pit depth (Svk). These parameters have been used by other researchers to detect ‘fuzziness’ (Rpk), to indicate tool wear (Rk), and to define anatomical features (Rvk) [4-6]. The aim of this paper was to find surface features that could be used as indicators for tool changes instead of today's’ scheduled ones. Besides, other surface deviations such as feed roller marks were of interest. The final goal is to gain a better understanding of sawn wood topography at the micro-mm range in order to utilize the potential of surface metrology for higher process control and to facilitate new manufacturing techniques for sustainable engineered wood products.
Rebeggiani SABINA (Halmstad, Sweden), Reddy VIJETH, Linus OLOFSSON
10:00 - 10:20 #38836 - Assessment of highly heterogeneous surfaces on the basis of cellular metals.
Assessment of highly heterogeneous surfaces on the basis of cellular metals.

Cellular metallic materials are a new, relatively young group of materials since around 1940. They are basically characterized by a lower mass density compared to the solid material. In other words, open structures are present in a given envelope volume of a body made of this material. This property has considerable application potential, making specific applications in medicine, filter technology and the chemical industry, among others, a possibility for the first time. In this respect, the manufacturing technology of the structures is a necessary prerequisite for process-reliable application. However, the basis for this is the evaluation of the suitability for production. For this purpose, a holistic system for the objective evaluation of highly heterogeneous surfaces was developed taking cellular metallic materials as an example. On the one hand, it is based on an optical method to evaluate cross-sectional images (Figure 1) that characterize the unprocessed state of the material and are generated by µCT or micrographs [1]. The processing condition is recorded using a tactile method. This is based on the use of a newly developed cutting-edge stylus tip in conjunction with a contour measurement instrument. As a result, specimens were analyzed that had been modified by milling, EDM and grinding operations (Figure 2). As a result, the influences of different machining conditions are analyzed in order to substantiate the suitability of the measuring method. In addition, one-dimensional parameters are introduced that can be used to evaluate and compare the surface condition and are based on the Abbott-Firestone curve. This information is a necessary prerequisite for interpretation of simulations of the surface state [2].
Uwe TEICHER (Dresden, Germany)

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CB-Day 2
10:20 - 10:40

Coffee Break


"Tuesday 28 May"

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D2Session 1B
10:40 - 12:40

Functional Applications

Moderator: Hassan ZAHOUANI (Professor) (Ecully Cedex, France)
10:40 - 11:00 #39598 - Wetting features of butterflies Morpho peleides and anti-icing behavior.
Wetting features of butterflies Morpho peleides and anti-icing behavior.

By using a biomimetic approach, an investigation was conducted to determine the connections between surface morphology and wetting. The interest is focused on the Morpho peleides butterfly. This butterfly is already well-known among researchers for its brilliant iridescent color and has inspired numerous innovations. The intricate structure of its wings is responsible for such color. However, this multiscale structure exhibits a multitude of other features, such as hydrophobicity. Given the limited research on the wetting properties of Morpho butterfly, a detailed analysis of its wetting behavior is proposed. Multiscale surface topographies of the Morpho peleides butterfly were analyzed using scanning electron microscope (SEM) and atomic force microscopy (AFM). To understand the relationship between morphology and wettability, a goniometer was employed to measured static and dynamic contact angle. The results revealed contact angles close to 136°, indicating a high degree of hydrophobicity. Moreover, sliding angles (SA) were measured in different direction: along and against the rolling-outward direction. The findings suggest anisotropic wetting. Specifically, when the wing was tilted along the rolling outward direction (i.e., away from the insect’s body) SA was about 7°. While, when the wing was tilted against the rolling outward direction, SA was about 29°. This phenomenon is directly linked to the butterfly’s survival strategy. As several studies have consistently demonstrated that superhydrophobic surfaces can effectively delay freezing, icing delay time on the Morpho’s wings was also measured. To investigate the exclusive morphological impact on anti-icing properties, polydimethylsiloxane (PDMS) replicas of the Morpho butterfly were obtained. In order to lower the viscosity of PDMS, hexamethyldisilane (HMDS) was added to aid in achieving complete molding without air inclusions. When compared to flat PDMS and a single textured scale PDMS, Morpho replications exhibited a longer freezing time. Therefore, this could be a source of inspiration for designing superhydrophobic surfaces with anti-icing applications or functional surfaces with controlled wettability.
Louise BURDIN (Lyon), Anne-Catherine BRULEZ, Radoslaw MAZURCYK, Jean-Louis LECLERCQ, Stéphane BENAYOUN
11:00 - 11:20 #39996 - From the rough side of the tracks- correlating surface condition of Pandrol brand rail clips with fatigue performance.
From the rough side of the tracks- correlating surface condition of Pandrol brand rail clips with fatigue performance.

Analysis of fatigue performance is critical to establish the suitability of safety critical components for service, due to the combination of static and dynamic stresses experienced during service in the rail environment. This paper demonstrates the influence of surface condition on the performance of PANDROL Brand resilient rail clips through programs of fatigue testing and surface characterisation, and seeks to develop a model correlating these observations. Pandrol Brand Rail clips are predominantly manufactured from as-rolled, round bar material. The hot rolling process can result in a wide variety of surface conditions between suppliers, dependent on factors such as pre-treatment of the billet, descaling practises, and roller maintenance schedules. During subsequent hot forming operations, this as-rolled surface roughness can be increased as the existing features on the inside of the curved sections of the component become exacerbated. The majority of failures that are experienced occur where the maximum point of surface roughening and the known peak-stress point of the component coincide. Extensive test work by the Pandrol FS Materials Laboratory has shown that the clip surface condition can have significant implications for component performance during fatigue loading, as the presence of stress-raisers provides locations for fatigue crack initiation. what aspects of the roughness profile program discussed here employs sample sets known to exhibit differing surface conditions, and two methodologies of fatigue testing are utilised to compare their performance. First, a program of fatigue testing is conducted where high levels of dynamic deflection are employed to induce failure in a large batch of samples, and the recorded test durations are treated statistically to allow for easy comparison between batches. Secondly, conventional SN curves are compiled to determine the fatigue limit for each sample set. Measurements using a contact profilometer have been taken from the critical area of each batch of components to determine the local surface roughness in the peak-stress region. The data obtained for the sample sets is compared, considering different combinations of roughness parameters to correlate the surface condition with the fatigue performance of the sample sets. Results show that the sample set with higher roughness levels, as depicted by a number of different parameters, exhibits a significant reduction in fatigue resistance. This work forms part of a wider investigation to define the roughness parameters which best characterise the observed fatigue performance. Identifying which aspects of the roughness profile best quantify the surface condition that defines the boundary between acceptable and unacceptable fatigue performance will ultimately allow Pandrol to better specify the surface quality required from raw material suppliers, thereby guaranteeing optimal clip performance from this perspective.
Liam LEE (Worksop/Huddersfield, United Kingdom), Liam BLUNT, Paul BILLS
11:20 - 11:40 #40218 - Assessment of selected quality features of models produced using 3D printing technologies.
Assessment of selected quality features of models produced using 3D printing technologies.

The paper presents selected results of research of specific quality features, mainly in terms of the surface layer of models manufactured using selected 3D printing technologies for applications in the casting industry. The formulated research topic is important mainly due to the fact that 3D printing is increasingly used in many type of industries, including casting, mainly in the lost material method and in the method of producing sand molds. In order to produce casting models enabling the formation of short production series in a very short time, it is necessary to produce models using 3D printing and maintaining appropriate quality both in terms of dimensional and shape accuracy, technological quality of the surface layer and resistance to abrasive wear (1). while maintaining adequate strength (2). As part of the project, three 3D printing technologies and the impact of technological parameters on the quality of the technological surface layer, mechanical properties and tribological wear of the manufactured models were tested. During the research the impact of parameters such as print direction, layer thickness, and laser process parameters on the quality of the produced models were analysed
Tomasz KOZIOR (Kielce, Poland), Pawel ZMARZLY, Damian GOGOLEWSKI
11:40 - 12:00 #40297 - Investigating the Impact of Massage and Novel Skincare Producon Skin Underlayers Mechanical Properties and Skin Tension.
Investigating the Impact of Massage and Novel Skincare Producon Skin Underlayers Mechanical Properties and Skin Tension.

The pursuit of effective skincare products that address skin aging concerns has led to the development of innovative formulations. This study aims to evaluate the influence of a cutting-edge skincare product on the mechanical properties of skin and its impact on the aging process. Utilizing advanced technologies such as surface topography and echography to study skin tension of the epidermis, dermis and fascia. The innovative device UnderSkin was used for to explore the quantitative changes in skin elasticity of the tree layers: epidermis, dermis and hypodermis. Participants in this study were subjected to a rigorous skincare regimen involving the application of the investigational product and massage over a 15 days period. UnderSkin analysis [1], a non-invasive imaging technique, was employed to visualize and quantify the structural changes within the skin layers. Comparative assessments were made against T0 measurements to discern the specific effects. Preliminary findings demonstrate a significant improvement in skin mechanical properties among participants. UnderSkin analysis unveiled notable changes in skin elasticity especially in the epidermis. These outcomes collectively suggest a positive influence on skin aging indicators, highlighting the potential of the product to mitigate the visible signs of aging. To study the balance of skin tension forces from topographical images and echography, the elastic model developed considers that the tissue is subjected to bi-axial cohesion forces in the orthogonal x and y directions of the image. The effect of the tension forces is studied through the wavelengths of surface topography and ultrasound imaging. The wavelengths of each image represent the trace of the displacements generated by the biaxial cohesive forces [2,3]. The deviation of the wavelengths along the x and y axes depends on the deviation of the forces: Δλ (F): Δ λ_^x (ΔF^x ), Δ λ_^y (ΔF^y ). The state of equilibrium of the skin tension forces is analyzed at the scale of the micro-structure of the tissue by the spectral decomposition of the image. A specific spectral method is introduced to separate the patterns oriented between 0 and 90°, and from 90° to 180°, by the Fourier transform (TF) in polar coordinates. The results show the beneficial effect of the cosmetic product on the improvement of mechanical tension after fifteen days of application. This research underscores the potential of the investigated skincare product and massage to positively impact skin mechanical properties and combat the aging process. The integration of skin surface topography, echography and UnderSkin analysis provides a comprehensive understanding of the overall changes on both surface and subsurface skin characteristics.
Alexandre BERGHEAU (Ecully Cedex), Gabriel CAZORLA, Alexandre BERGHEAU, Aurelie PORCHERON, Youcef BEN KHALIFA, Roberto VARGIOLU, Hassan ZAHOUANI
12:00 - 12:20 #40312 - Optimization for surface finish of parts manufactured by polymer laser powder bed fusion.
Optimization for surface finish of parts manufactured by polymer laser powder bed fusion.

Laser powder bed fusion (L-PBF) for polymers is one of the many additive manufacturing technologies that has since many years been associated with rapid prototyping. It can produce parts with complex geometrical shapes that are not possible in injection moulding (IM). However, the final part qualities such as surface roughness, mechanical performance, and dimensional accuracy are not comparable to what can be achieved by IM. As the name suggests, L-PBF final part quality has a significant reliance on the ‘laser’, hence this research was carried out to investigate the dependence of surface finish on laser scanning process parameters and then optimize for it. Studies show that laser scan spacing, laser scan speed, and laser power, which directly influence the consolidation energy input into the powder, are primary contributors to surface finish quality [1]-[2]. A two-level full factorial design of experiments (DOE) built around the process parameters of laser power, laser scan spacing, laser speed, and number of contour layers (upskin, downskin, and side) was used to manufacture the parts, i.e. 2^4. The parts were characterized for surface finish using a focus variation microscope after being post-processing by pressurised media blasting. There are trends of a direct correlation between roughness reduction increase in consolidation energy input but at high energy consolidation input significant loss of final part micro-feature resolution is observed. However, results indicate that the surface finish depends mainly upon the laser process parameters of the contours (upskin, downskin, and side). Based on the results from the DOE the surface finish can be improved by optimizing process parameter values corresponding to a reduction in surface roughness parameter, Sq (root mean square height) values of the final part. The values can be reduced by at least 5% overall and up to 30% on selected faces. Further work needs to be carried out to find a process parameter span in the relatively higher consolidation energy zone within which parts with reduced roughness can be obtained without compromising micro-feature resolution.
12:20 - 12:40 #40305 - Texture, gloss and color variation and perceived quality of materials - The challenge with sustainable plastic surfaces in car interior design.
Texture, gloss and color variation and perceived quality of materials - The challenge with sustainable plastic surfaces in car interior design.

Todays demand of a reduced carbon footprint within the manufacturing industry results in higher demands of the sub suppliers of components and raw material. The plastic industry, together with research in the field, has been working in decades with the recycling process to ensure the recyclability of different polymers. However, the demands on perceived quality of plastic components have tightened in the field to remain in a premium segment and the specification of plastic components in a car interior are probably stricter than ever. The question is, does todays tolerances of plastic components regarding design and perceived quality, serve in harmony with a higher level of recycled material in future components, or should the industry adapt its tolerances to a more sustainable process? Texture, gloss and color variation significantly impact the perceived quality of materials and have been an issue historically within the manufacturing industry of plastic components. This paper handles the result of a pilot study where typical gloss and color variation in plastic pieces was evaluated. The gloss and color variation occurs generally more often with increased recycled content, however in this study the gloss and color variation was simulated and controlled in virgin material.
Bergman MARTIN (halmstad, Sweden)

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12:40 - 13:30

Show demo by ZEISS


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13:30 - 14:30

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14:30 - 15:10

Keynote Presentation 4

14:30 - 15:10 Importance of quality control in industry and its challenges for tomorrow. Franck THIBAULT (Keynote Speaker, Ruel Malmaison, France)

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D2-Session 2
15:10 - 16:10

Measurement, Instrumentation &Characterization in Metrology

Moderator: Bengt-Göran ROSÉN (research manager) (Halmstad, Sweden)
15:10 - 15:30 #39030 - Toward dynamic surface metrology in roll to roll manufacture of flexible electronics.
Toward dynamic surface metrology in roll to roll manufacture of flexible electronics.

Roll-to-roll printing (R2R) is a critical process for the production of large area flexible electronic devices e.g. flexible photovoltaics. R2R production proceeds by the process of printing or depositing of multiple layers of conductive tracks in a controlled and positionally defined manner on meter wide flexible polymer substrates. R2R has revolutionised flexible device production if the print operating variables and web (substrate) handing are well controlled and optimised. R2R manufacture has developed capabilities from conventional paper through to high value components. Such devices have high demands on the geometric precision (spatial positioning and track thickness) to tight manufacturing specification <1um film thickness[1]. Slot-die printing technologies are commonly used in R2R to deposit conducting inks tracks to a range flexible substrates. In slot-die printing, the uniformity of printed films is directly linked to the operating variables such as ink pump flow-rate, speed of the web, ink drying and print gap [2,3]. Imperfections in R2R operation lead to unwanted topography variation, thickness/width variation or defects in thin film surfaces. This results in low productivity and large amount of waste. Unfortunately, current R2R practice is largely limited to post process metrology of the printed film surface and track dimensions, this can result in excessive wastage and increased processing costs. Real time film surface monitoring giving reliable quantitative information to process controllers is the key to successful R2R closed loop processes. The present paper presents the development of a dynamic surface assessment approach based on in plane and out of plane surface metrology facilitating successful R2R closed loop processes.
Liam BLUNT (Huddersfield, United Kingdom)
15:30 - 15:50 #38844 - Profile Reconstruction from Scattering Light Distributions Based on Sparse Dictionary Learning.
Profile Reconstruction from Scattering Light Distributions Based on Sparse Dictionary Learning.

The angle resolving scattered light technique is a powerful tool for inline roughness measurement of fine machined surfaces. The key features of the sensor are that it is robust against vibrations in the direction of the optical axis, that a high measuring speed can be achieved and that extremely fine roughness structures down to the nanometre range can be detected. In many applications it has been shown that the shape of the measured angular distribution correlates very well with the tribological behaviour of functional surfaces. However, it is not trivial to establish a direct relationship between the angle-resolved data from scattered light sensors and the spatially resolved surface topography. The reason for this is the non-coherent light source used (and thus the lack of phase information), which makes it difficult to obtain direct depth information about the surface topography. This makes it difficult to compare the data from the angle resolving scattered light sensor with other surface measuring devices. To solve this problem, we present a method for the reconstruction of surface profiles from angle-resolved scattered light measurements. The mapping from the given scattered light data to surface topography is not unique, and the reconstruction of said surface topography can be classified as a non-linear inverse problem. Two key elements are necessary to solve the non-linear inverse problem. Firstly, an accurate and fast simulation of the measurement process is needed. For this purpose, we have modelled an optical digital twin of a commercially available angle resolving scattered light sensor with all the important optical features. The digital twin is programmed in C++ language with a Python interface. A virtual "real-time measurement" can be carried out through parallelisation. Secondly, a simplified model of the surface profile is needed. And for this purpose, we propose a model based on a sparse approximation of a certain type of surface topography. In previous studies, we have successfully used a Fourier based sparse approximation for turned profiles. In this work, we have generalized the sparse approximation technique using machine learning algorithms from the domain of sparse dictionary learning. We will present several examples of surface reconstruction from in-process scattering light measurements and compare the reconstructed profiles with the profiles measured by a tactile measurement system.
Jörg SEEWIG (Kaiserslautern, Germany), Tycho GROCHE
15:50 - 16:10 #38837 - Mathematical softgauges for material ratio parameters.
Mathematical softgauges for material ratio parameters.

Editors of surface texture analysis software need to validate their calculation, ideally with an implementation-independent manner. Today, there is no universal reference for parameters, and especially for material ratio parameters, Rk parameters, and volume parameters that are based on the Abbott curve. At Digital Surf, we developed validation, several years ago, that are based on mathematics. Softgauges are created using mathematical signals and parameters are expressed by mathematical formulae. By injecting the softgauge equation through the parameter equation, it is possible to obtain a mathematical expression of the “true result”. Then, softgauges are created as files with enough resolution and used to test software calculated. This method makes it possible to confirm that a calculation algorithm is correct, but it also provides a way to check the sensitivity of a particular parameter or a particular algorithm to influence factors such as noise, outliers, slope, etc. For this study, two families of softgauges were designed to test material ratio parameters. The two main goals of this study were, 1) to obtain reference values for all parameters based on the Abbott curve, and 2) to have a method that is independent from any implementation.
François BLATEYRON (Besançon), Stéphane BRETON

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CB-Day 2b
16:10 - 16:30

Coffee Break


"Tuesday 28 May"

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16:30 - 17:30

Measurement, Instrumentation &Characterization in Metrology

Moderator: Liam BLUNT (Research Professor) (Huddersfield, United Kingdom)
16:30 - 16:50 #38838 - Influence factors on the topography fidelity determination of optical measuring instruments.
Influence factors on the topography fidelity determination of optical measuring instruments.

The standardization considering the calibration, adjustment and performance verification of areal surface topography measuring instruments was recently published. The topography fidelity is one of the basic metrological characteristics as defined by the new ISO calibration framework and must be considered and analysed in the scope of a comprehensive calibration [1] [2] [3]. The procedure for the determination of this property has first been described in 2014, and a first approach for the consideration of its influences using the propagation of measurement uncertainty in topography measurement was proposed by Leach et al. [5]. However, there is still a lack of practical experience in the evaluation and comparison of the topography fidelity. We describe an experimental comparison of the determination of the topography fidelity and identify influential factors on the results. An additively manufactured chirp material measure is measured with different optical surface topography measuring instruments including white-light interferometers, confocal microscopes, focus variation instruments and optical profilers. Using the pool of available measurement data, the challenges in the implementation of the topography fidelity evaluation can be demonstrated. The number of extracted and averaged profile can have an influence on the evaluated results. Also, in the additional evaluation and interpretation of the results of the metrological characteristic some parameters can be varied that lead to a change of the results. But besides the algorithmic influences, also the relation between the parameters of the measuring instrument, like the sampling interval, the numerical aperture, or the magnification and the evaluation results can be demonstrated. Additional statistical evaluations show correlations between the distribution of the topography fidelity and the characteristic values of the instruments. The results emphasize that the topography fidelity is a metrological characteristic with a high information content, that allows a comparison of the transfer characteristics of various types of surface topography measuring instruments. It can be shown that there are still open questions in the evaluation and interpretation of the characteristic, especially with regard to its contribution to the measurement uncertainty.
Matthias EIFLER (Erfurt, Germany), Julian HERING-STRATEMEIER, Georg VON FREYMANN, Jörg SEEWIG
16:50 - 17:10 #40984 - Improvement of roughness surface of additively manufactured 316L steel by selected post-processing application.
Improvement of roughness surface of additively manufactured 316L steel by selected post-processing application.

Additive technology, or 3D printing, has been an extremely progressive technology in recent years and is gaining more and more attention, not only due to its variety of printable materials (polymers, composites, resins, metals, etc.), but also thanks to design freedom. However, one of the main problems in 3D printing is the unsatisfactory surface, which is characterized by increased roughness. This is due to several reasons. The first reason is the principle of layer-by-layer printing, where a gap can form between the individual layers, resulting in a depression. The second reason, mainly in metal printing by the Selective Laser Melting (SLM) method, is the so-called balling effect [1], when the fusion of individual grains and gas denudation [2] occurs, these balls then stick to the surface and create a rough surface. The last mechanism of high surface roughness is the manual removal of support elements. After removing these elements, a very rough surface remains. All these roughnesses need to be reduced or eliminated through post-processing. The presented article is devoted to selected post-process modifications such as blasting, tumbling, grinding and electropolishing in connection with additive SLM technology and AISI 316L material. A Renishaw AM400 device was used to print the samples and a total of 20 samples were produced, on which the individual mentioned methods were gradually applied with different settings. An optical microscope Infinite Focus G5 from Alicona was used to measure selected roughness parameters, see Fig. 1. The main deciding factor in assessing the quality of the surface was the average arithmetic height of the given area (Sa) and the maximum height of the assessed area (Sz). Sz is the maximum distance between the highest peak (Sp) and the lowest point of the assessed surface (Sv). Another 10 parameters were measured and evaluated, the most important of which is the average square height of the assessed area (Sq). The measurement itself and setting the sample on the measuring surface took approximately 3 minutes. In total, 35 measurements were performed in accordance with EN ISO 25178–2:2013 [3]. Through successive testing, it was found which method of post-processing treatment is the most effective, see Table 1. At the end of the research, the results and recommendations for further research are presented, this research also serves as a basic research for further research, when the internal contours of the surface will be tested and will be improved surface inside the product, e.g. channels or lattice structures.
Jiří HAJNYŠ (Ostrava, Czech Republic)
17:10 - 17:30 #40042 - Parameter optimisation for AM printed tungsten for the improvement of surface finish.
Parameter optimisation for AM printed tungsten for the improvement of surface finish.

The complexities and challenges faced whilst fabricating tungsten based components have resulted limitations in their design and utilisation [1]. Tungsten’s use in challenging and harsh environments, often extreme high temperature applications is due to the desirable thermal and mechanical properties, such as its inherent hardness and high melting point. These characteristics have made tungsten an ideal candidate for next generation nuclear fusion energy and tooling applications. Manufacturing parts for such applications has been severely limited where subtractive machining is concerned [2]. For these reasons, the possibilities additive manufacturing (AM) offers could be profound, particularly for components of high complexities. Additively manufacturing tungsten has proved very challenging due to the required energy input and has been largely limited to electron beam-based processing. Additionally, surfaces produced through an AM approach have been recognised as often inferior to those produced through traditional methods and therefore post processing is often required. As a means to reduce this requirement, improving the quality of the as-printed surface could be beneficial. This work has focused on laser powder bed fusion (LPBF) processes and on parameter optimisation for the improvement of surface finish and the effects of a strategy to remelt the deposited layers. A sample cohort of 10 mm pure tungsten cubes were produced through an LPBF approach using a Renishaw AM 400 with reduced build volume and has employed variations in remelt strategies. Focus Variation Microscopy (FVM) was used for the analysis of the surface with ISO 25178 compliant surface characterisation being undertaken. Reductions in surface roughness (Sa) were achieved with a remelt strategy as opposed to the ‘as-printed’ counterpart. The as-printed cohort produced a Sa range of 16-20 μm (figure 1, left), this was reduced to 7-10 μm s (figure 1, right) for all samples that underwent a remelt procedure, with the lowest recorded (7 μm) for the sample undergoing double exposure remelt strategy. This is a novel use of LBPF for such hard materials and potentially opens up the possibility of manufacturing complex tungsten parts by the more widely used LBPF processes. The findings from this research concluded that the print/ build parameters have a significant effect on the overall build quality of tungsten AM components, including its surface finish.
Ahmed TAWFIK (Huddersfield, United Kingdom), Christopher JACKSON, Ahmed HASSAN, Liam BLUNT
Wednesday 29 May

"Wednesday 29 May"

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08:00 - 08:40

Keynote Presentation 5

08:00 - 08:40 Importance of surface properties for real contact area formation. Kalin MITJAN (Keynote Speaker, Slovenia)

"Wednesday 29 May"

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D3-Session 1
08:40 - 10:40

Tribology and Wear Phenomena

Moderator: Hamid ZAIDI (Professor) (Poitiers - France, France)
08:40 - 09:00 #39611 - Surface modification of nanoMOFs with microgels for tribological application.
Surface modification of nanoMOFs with microgels for tribological application.

Osteoarthritis (OA) is a chronic and progressive joint disease characterized by cartilage destruction, synovial thickening, joint space narrowing, osteophyte, and calcium crystal deposition, which affects hundreds of millions of people worldwide [1,2]. Synergetic therapy is an emerging platform for the treatment of OA [3,4], which can provide long-term joint lubrication without shear thinning and restrain the systematic toxicity from oral administration. However, the construction of porous nanocarriers with good lubricating performance and stimuli-responsive drug release is still challenging. We develop a hybrid nanocarrier by growing hydrogel layers on surface of metal-organic framework nanoparticles (nanoMOFs) via one-pot soap-free emulsion polymerization. The core-shell structure of nanoMOFs@microgel demonstrated high-temperature aqueous dispersion stability. Using as aqueous lubricating additives, the hybrids enabled reductions in both the coefficient of friction and wear volume. By co-culturing the anti-inflammatory drug-loaded nanoMOFs@microgel with human normal chondrocytes, the hybrids showed good biocompatibility and anti-inflammatory effect on the chondrocytes with inflammation by regulating the expression of OA-related genes. Our work establishes multifunctional biolubricant system for efficient OA treatment and biomedical application.
Jianxi LIU (Xi'an, China), Lejie TIAN
09:00 - 09:20 #40311 - Micromechanical and tribological behavior of an Al-Fe-Cr alloy obtained by Selective Laser Melting (SLM) and its impact on surface topography after polishing.
Micromechanical and tribological behavior of an Al-Fe-Cr alloy obtained by Selective Laser Melting (SLM) and its impact on surface topography after polishing.

Additive manufacturing (AM) processes and corresponding process parameters provide a wide range of structures and mechanical properties. For example, the development of a composite structure with harder particles embedded in a softer metal matrix can lead to the formation of a mechanical blend layer (MML) that significantly decreases the coefficient of friction (COF) and improves wear resistance [1]. In this work, a composite with reinforced quasi-crystalline Al-Fe-Cr aluminum matrix was initially manufactured by selective laser melting (SLM), using a prealloyed Al-Fe-Cr powder. After AM processing, the sample microstructure was composed of a region with coarse quasi-crystals (QCs) particles and a region with fine QC particles (Figure 1). Samples were later characterized by nanoindentation, for evaluation of hardness and elastic modulus of both regions. In parallel, scratch test procedures [2] were conducted on the sample surface, to characterize the effect of a single abrasive particle on both regions. Profilometry tests were conducted to analyze the volumetric loss after the scratch tests and to study the topographic difference of the scratches in both regions. It was identified that the region of fine particles presented an elastic modulus for low nanoindentation load values that is lower than that of the region with coarse particles (Figure 2a). Besides, during the scratch tests, changes in the abrasion micromechanisms were noted as a function of the variation in normal load. Scratch tests have also indicated how the friction and wear behavior was affected by microstructural features, such as quasi-crystal particle distribution (Figure 3). In the end, profilometry analyses indicated that the fine particle region presented the largest volumetric losses after the scratch tests (Figure 2b), corroborating the results of the nanoindentation tests. Results of the micromechanical analysis were later correlated with the behavior of the sample in mechanical polishing (with abrasive sizes down to 0.06 µm), also characterized by profilometry, after which it was noticed that the fine particle region, topographically, is below to the region of coarse particles.
Vinicius LIMA (Sao Paulo, Brazil)
09:20 - 09:40 #39883 - Impact of Polyphenols and Plant Proteins on the Oral Epithelium Topography.
Impact of Polyphenols and Plant Proteins on the Oral Epithelium Topography.

The global ecological context is compelling agri-food industry professionals to increase the production of sustainable food by expanding plant-based protein production. However, foods containing these types of proteins often have a very astringent taste with sensations of dryness, puckering, and a non-juicy perception [1]. The components responsible for astringency are known as polyphenols [2]. This sensation is due to the loss of lubrication on the epithelium because of the aggregation of polyphenols and plant proteins with epithelial proteins such as MUC1[3]. An oral epithelium model was developed to evaluate the effect of polyphenols and plant proteins on epithelium model lubrication and to analyse the protective mechanisms established by the oral mucosa to limit polyphenol and proteins damages before and after friction. An original tribometer was developed within the scope of this work to perform friction on the epithelium model. Tests were conducted by applying polyphenols to epithelium models to examine their effects. In certain cases, proteins rich in proline (PRPs) were additionally introduced to assess their protective capacity against polyphenols. To analyse the effects of these elements, we investigated damage surfaces as well as topographies as indicators. According to the literature, polyphenols induce aggregations that may disrupt epithelial lubrication, thereby resulting in a sensation of astringency [4]. The results of this study indicate that the addition of polyphenols and plant proteins altered the topography of epithelium models, leading to an increase in roughness that characterizes polyphenol aggregation on the surface, see Figure 1 . This topographical alteration is also correlated with an increase in friction forces. Importantly, the study demonstrated that the prior addition of PRPs mitigated the impact of polyphenols, thereby reducing the alteration of the topography. The analysis of damage also revealed that the presence of polyphenols and plant proteins caused more significant damage after friction compared to samples without astringent component addition. These damages were also less pronounced in the presence of PRPs. In conclusion, this study highlights that polyphenols and plant proteins disrupt the surface of oral epithelium models, as evidenced by the alteration of topography associated with an increase in friction forces. These findings suggest that these astringent compounds disturb epithelial lubrication, giving rise to the sensation of astringency. However, the presence of PRPs appears to play a protective role by limiting aggregations, thereby reducing the sensation of astringency and mitigating the effects of polyphenols and plant proteins.
Ianis AMMAM (Lyon), Cyril PAILLER-MATTÉI, Lucas OUILLON, Clement NIVET, Roberto VARGIOLU, Fabrice NEIERS, Francis CANON, Hassan ZAHOUANI
09:40 - 10:00 #39906 - Study of tribofilm formation in a sliding electrical contact: correlation with wear and electrical performance.
Study of tribofilm formation in a sliding electrical contact: correlation with wear and electrical performance.

Recent interest in improving lifespan of electrical slip rings for application in wind turbines has renewed the need for deeper understanding of sliding electrical contact operation. In contact slip rings using graphite-based brush technology, the creation of a tribofilm, or “patina”, at the interface with the metal slip ring is a well-known phenomenon [1, 2]. In this scope, the study of its formation in a bronze/silver-graphite contact has been conducted. The test bench is based on an instrumented industrial slip ring specific for wind turbine application (Figure 1). It permits to measure the electrical performance of the contact during the rotation. The electrical resistance measurement, coupled with an encoder for the angular position, allows to draw the electrical resistance as a function of both the number of cycles and the position of the brush on the ring. Thanks to this, we are able to link the electrical performance to the structural and chemical state of the tribofilm. We performed surface and structural observations with optical microscope and SEM/TEM/EDX, as well as advanced chemical surface characterization with XPS and Raman spectroscopy. Thanks to this multitechnique analysis, a scenario of tribofilm formation on the metallic surface of the slip ring has been proposed, and permits to justify the evolution of the electrical performance of the sliding contact (Figure 2). Wear measurements on the silver-graphite brushes were also conducted. The results show an influence of both the electrical current direction and the brushes sliding direction on wear. If the polarity effects were already documented in the literature [3-5] and can be explained by oxidation phenomena, the effect of the sliding direction seems to be more peculiar. We suspect the loose third body, composed by powdery wear debris, to be responsible for the reduction of the brush wear. It could explain why the effect of sliding direction is not well described, since it would depend on the contact geometry and its debris retention capability. Further investigation will be undertaken to confirm this hypothesis. We also want to estimate the impact of a modification of the roughness of the metallic ring, which could play a role in the debris retention and the tribofilm formation.
Timothée DOUTRIAUX (Ecully), Siegfried FOUVRY, Sébastien LAROUSSE, Manon ISARD, Olivier GRATON, Maria Isabel DE BARROS BOUCHET
10:00 - 10:20 #40300 - Effects of cosmetic treatments on the biotribology, vibrational and sensorial properties of a single human hair fibre.
Effects of cosmetic treatments on the biotribology, vibrational and sensorial properties of a single human hair fibre.

Everybody wants beautiful hair that is pleasant to touch. Indeed, hair has great social significance for human beings as it reflects our physical state. Thus, for many years, especially in the second half of the 20th century, scientists have focused on the physical and chemical properties of hair and developed methods of evaluation based on scientific values. We propose to explore the tribological and morphological hair changes due to chemical and thermomechanical treatments. Caucasian hair samples were used. We studied the effect of chemical and thermomechanical treatments on the sensorial properties of hair. The morphology of hair was evaluated using optical interferometry and wavelet analysis. A haptic tribometer system to perform the friction tests and simultaneously measure the friction force and the vibrations between the probe and the hair surface. Several key results were obtained in this study. First, a new method using wavelet decomposition of a surface was used to quantitatively evaluate hair cuticle modifications at different scales. The SMa and NAD parameters were found to be good indicators of the sensorial properties of hair (softness and brightness). Then, we introduced vibration analysis during the friction test as a new parameter to study the tribological behavior of the hair surface. The acoustic vibratory level was found to be a good indicator of the hair surface’s softness. Furthermore, the dependence of the frequency peak of the induced vibrations during the friction tests, with respect to the roughness of the hair surface was demonstrated. An increase in roughness corresponds to a peak of higher amplitude. Finally, it appeared that coloring and bleaching hair damaged it and impacted its sensorial properties: the hair fiber became less soft, less bright and rougher. Moreover, applying thermomechanical treatments to damaged hair improved sensorial properties by smoothing the surface and erasing the asperities. Thus, the hair fiber appears brighter and smoother.

"Wednesday 29 May"

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10:40 - 11:00

Coffee Break


"Wednesday 29 May"

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D3Session 1B
11:00 - 13:00

Tribology and Wear Phenomena

Moderator: Caroline RICHARD (Tours, France)
11:00 - 11:20 #38777 - Tribological characterization of surfaces featuring functional properties in the phase space by combining topography measurement with scattering light measurement.
Tribological characterization of surfaces featuring functional properties in the phase space by combining topography measurement with scattering light measurement.

Typically, functional characterization is implemented using profile of areal surface topography. Common evaluation methods include the function-oriented surface texture parameters defined by ISO 21290 and ISO 25178-2. The tribological performance however does not only correspond to the statistical distribution of height values but, because of fractal characteristics [1] [2], is also majorly influenced by the gradients: Coulomb already noted that friction between two surfaces is caused by "interlocking of surface asperities" [3]. Popov stated that the surface gradient is one of the “main representative surface parameters” for friction [4]. The calculation of the surface gradient based on the measured topography is sensitive to noise, so that a direct measurement is essential. Thus, for a comprehensive functional characterization, a measurement of both the topography and the surface gradients are useful. If the displacements of a coordinate z are interpreted as the position of a particle and its derivative as velocity (or massless momentum) z ̇, two new coordinates q and q ̇ can be assigned to them. Each "coordinate particle" ξ_i has a state in the phase space defined by its position coordinate q and its "momentum coordinate" q ̇. The surface itself is represented by the new bivariate probability distribution p(q,q ̇). A comparison of surface profiles can demonstrate that a function-oriented characterization of the surface, which considers lubricant film thickness as well as the contact mechanical properties of surface slopes, can be described by this distribution, and different phase space representations can result even with identical values of function-oriented parameters. We describe the general definition of the state space approach for the functional characterization of surfaces and its application in specific use-cases. A direct measurement of the state space can be achieved, when both an angular and topographic measurement are implemented: Scattering light methods, as described normatively, for example in VDA2009 [5], have long been used successfully as a means of production monitoring and allow a direct measurement of the statistical distribution of surface angles. However, their advantages in terms of robustness against environmental factors such as vibrations or aerosols and their high measurement speed have been the primary focus, distinguishing them from tactile, confocal, or interferometric methods. The method described in VDA2009 is traceable through calibration with suitable standards [6], making it suitable for industrial quality management. In practice, it is used, for example, in the specification of worm gears with high efficiency requirements [7]. By combining angle-resolved scattering light measurement technology with a topography measurement method, such as confocal microscopy, a direct measurement of the described state space representation can be achieved, as both the height distribution and the statistical distribution of gradients are known. One example is shown in Figure 1, where the measurement of the track of the flat roller of an Amsler pin-disk test run is shown [8]. Both 286,720 color-coded Aq values (variance of the local angular scattering light distribution) from a measurement spot with a diameter of 300 µm over a width of 1 mm with a roller diameter of 30 mm just as well as, the topography of a 320 x 320 µm section is shown, captured with a confocal microscope (NA 0.8, 50x, F-operator 2nd order). Positions A and B represent the surface before and after a 50-hour load with 2 GPa. The change to a left-skewed height profile and a dramatic thinning of the gradient distribution is clearly visible. The latter is also evident in the scattering light measurement across the entire contact area, where not only local information is provided, but also the dispersion of all contact areas can be discussed through multiple parameters.
Boris BRODMANN (Karlsruhe, Germany), Matthias EIFLER
11:20 - 11:40 #40303 - Changes in surface topography during running-in of bearing steel contacts under mixed lubrication.
Changes in surface topography during running-in of bearing steel contacts under mixed lubrication.

The running-in is the initial process for new moving parts wearing against each other to establish the surface shape that will transition into a stable relationship for the rest of their working life. The objective of this research is to investigate and evaluate the running-in process that occurs in rolling-sliding contacts under mixed-lubrication conditions where the contact is partly under boundary lubrication (BL) and partly in EHL. Running-in typically involves permanent changes to the surface topography involving asperity flattening through mild wear and plastic deformation. To improve the prediction of service life or friction of rolling-element bearings under mixed-lubrication conditions, knowledge of surface topography changes during running-in and their dependence on the operating condition is an important prerequisite. This paper describes the changes in surface topography due mechanisms such as wear, plastic flow and elastic-plastic deformation, during running-in under typical rolling element bearing conditions. AISI 52100 steel specimens were tested, with a surface finish between 0.02 and 0.03 µm Ra, in a mini traction machine (MTM) and a TE74 twin disc tribometer instrumented with friction and contact potential measurement in the presence of a synthetic (PAO) base oil, operating in the mixed lubrication regime. Roughness trends over the running-in period for S (3D) and R (2D) roughness parameters are analysed to such that these measurements were made successfully on surfaces with initial Ra of 20 nm thus presenting nanometre scale changes. A novel method of pre and post-test surface relocation with 3-D optical profilometry and scanning electron microscopy (SEM) was implemented for the worn flat MTM disc while measurement of the curved and highly reflective surfaces of the TE74 were obtained using 2-D surface profiles using a Taylor Hobson Intra Touch contact profilometer. Rolling-sliding tests under different contact conditions (i.e. specific film thickness () values, slide-to-roll ratio (SRR) and entrainment speed) were performed to study the effect of these contact conditions on the changes in surface topography during running-in. Asperity scale detail of running-in is presented showing elastic or plastic deformation and/or wear of asperity peaks. When plastic deformation occurs, it is accompanied by material flow from the peaks onto the adjacent valleys [1]. This mechanism is detected by changes in valley depth and skewness values with up to a 25% change. The work shows running-in influences the lambda ratio and that a new definition using surface skewness should be considered to better capture contact conditions and explain the transition from mixed BL/EHL to EHL or EHL/hydrodynamic lubrication regimes and thus friction levels. Previous work used the plasticity index ψ, surface roughness parameter β, real contact area ratio A0* but these do not fully capture the evolution of contact roughness during running-in [2]. The results exhibit the rapid nature of running-in and how most of the surface topography changes occur in the first few load cycles. The number of cycles needed for the surfaces to reach steady state are also presented. Surface topography transitions such as asperity removal due to wear, increase in the load-bearing area of the asperities and in tests with slip, plastic flow of material from peaks into adjacent valleys are shown at high magnification. These results are compared with trends seen in the friction and contact potential difference (CPD) to help interpret the actual lubricated contact conditions.
Terry HARVEY, Robert WOOD (Southampton, United Kingdom), Maruti SAKHAMURI
11:40 - 12:00 #40308 - Profilometric measurements of wear volumes of discs and balls after reciprocating sliding.
Profilometric measurements of wear volumes of discs and balls after reciprocating sliding.

In most cases, wear is undesirable because it can cause loss of machine usefulness or material failure. To achieve accurate wear predictions in industrial applications tests should be performed in conditions that simulate the exact wear process. Gravimetric method is one of the simplest ways to measure wear. It is problematic to use it for very low wear values and for very heavy elements. Wear can be examined precisely using profilometric method [1, 2, 3]. Measurement of only worn scars can be used typically for wear testing using test rigs. The wear volume can be calculated from equations based on the shape of the scar. However, the methods existing in the standard are indirect, based on approximation, and difficult to consider plastic deformations. The experiments were carried out in reciprocating sliding using the Optimol SRV5 tester in ball-on-disc configuration. The strokes were between 0.2 and 2 mm. After tests, surface topographies of balls and discs were measured using white light profilometer Talysurf CCI Lite. Wear volumes of worn scars on the disc surface were obtained using two methods. The ASTM D7755-11 standard [4] should be used for strokes less than 2.5 mm. Sizes of wear scares and only one cross-sectional profile is needed (Figure 1) for approximation of the volumetric wear. The middle zone A and rounded zones B are included. Volumetric wear of discs were also calculated directly from the results of areal topography measurement. Figure 2 presents examples of contour plots of wear scars. Wear volumes of balls were also calculated using two methods. According to ASTM G133-05 standard [5] volumetric wear was approximated based on the diameter of truncated ball. Wear volumes of balls were also calculated using the results of areal surface topography measurement. It was found that the application of the ASTM D7755-11 standard typically led to overestimation of volumetric wear of disc. Procedure of improving this standard was proposed. Calculation of volumetric wear of ball typically according to ASTM G133-05 standard typically led to underestimation of the result compared to direct wear measurement. Possible errors in wear levels determinations were discussed. Limitations of profilometric measurement methods were considered. In the future, existing standards related to scar measurements should be modified, considering methods of areal measurements of wear scars. These standards should include detailed procedures of wear scar measurement and analysis. Human judgment is an important factor that affects the accuracy of wear measurement.
Pawel PAWLUS, Rafal REIZER (Rzeszow, Poland)
12:00 - 12:20 #38833 - Relevant texture parameters versus rolling resistance – a parametric study of various asphalt mixes.
Relevant texture parameters versus rolling resistance – a parametric study of various asphalt mixes.

Transportation is responsible for about a quarter of the Europes’s greenhouse gas (GHG) emissions. Within this sector, road transport is by far the biggest emitter accounting for more than 70% of all GHG emissions from transport in 2014 [1]. This environmental footprint is not compatible with a worldwide ambition and effort to steadily reduce the GHG emissions associated with the transportation sector. One of the factors affecting vehicle’s fuel economy is rolling resistance. Rolling resistance is a physical phenomenon related to the dissipation of energy that occurs during the passage of a tire on a road pavement [2, 3, 4]. This loss of energy generates forces opposed to the vehicle movement, which in turn increase fuel consumption. Three physical phenomena can be identified that explain rolling resistance: 1) deformation of the tire in the tire/road contact area, 2) aerodynamic drag of the rotating tire, and 3) slip between the tire tread and the pavement surface. Rolling resistance can represent until 30% of the resistive forces depending on the vehicles’ characteristics and the driving conditions (rural or urban roads, motorways). According to several studies, rolling resistance is responsible for 5 to 20% of the fuel consumption of a passenger car and 15 to 40% of trucks’ fuel consumption. It depends on multiple factors related to the vehicle type (load, suspension), tyre properties (rubber, inflation pressure, rubber temperature), vehicle operating conditions (speed), atmospheric conditions (wind, temperature) and road pavement characteristics (roughness, macrotexture). However, the factors described previously can have opposite effects on rolling resistance and their real individual contribution is difficult to assess. Moreover, the effect of pavement surface texture is not well known and more particularly the role of various texture scale on the rolling resistance. This paper presents a laboratory study performed on sixteen asphalt mixes designed with several aggregates’ sizes and mineralogical compositions, different sand types and different types of binder. Consequently, they exhibit various surface textures. Rolling resistance measurements are performed thanks to a new laboratory test using the machine Wehner & Schulze [6]. Texture measurements are realized with laser profilometer and a wide range of texture parameters defined in ISO 25178 series are estimated. Statistical analysis are performed to determine the most relevant texture indicators to explain rolling resistance. Parameters such as RMS (Root Mean Square height) and Smc (Inverse Areal Material Ratio) appear as the most correlated with rolling resistance, which can be explained by the fact that an increase in roughness entails an increase of the energy losses by indentation phenomenon.
Donatien DE LESQUEN, Veronique CEREZO (Lyon), Enzo MARIETTE, Julien VAN ROMPU, Manuela GENNESSEAUX
12:20 - 12:40 #40307 - Effect of laser texturing and DLC coating on seizure resistance in reciprocating sliding.
Effect of laser texturing and DLC coating on seizure resistance in reciprocating sliding.

Surface texturing is a method leading to an improvement in tribological properties of assembly by creating dimples on sliding surface. These dimples may cause a decrease in friction. Surface texturing can be used also to increase in the seizure and abrasive wear resistances. This technique is very popular, and applications of surface texturing were described elsewhere [1-3]. There are many texturing techniques, including burnishing [4] and abrasive jet machining [5]. However, laser texturing is the widely used technique [6]. Typically circular dimples are employed, they are characterised by depth and diameter. The ratios between the depth and diameter of the circular dimples are between 0.01 and 0.1 [7]. The experiments were carried out in lubricated conformal reciprocating motion using the Optimol SRV5 tester. The contact region had the shape of the ring. The lower disc was the sample while the upper disc was a counter-sample. Both discs were prepared from 42CrMo4 steel of 44±2HRC hardness. Only samples (lower discs) were textured and DLC coated. Before each test, a drop of mineral oil L-AN-46 was supplied to the contact area. Seizure resistance tests were carried out under the following conditions: stroke 3 mm, normal load 1000 N, frequency of oscillation 20 Hz, and initial temperature 300C. Maximum test duration was 2 hours. Tests were stopped when the coefficient of friction reached 0.3 or temperature was higher than 1000C. Maximum test duration was 2h. Figure 1 presents the example of test result. The untextured sample without DLC coating led to the increase in the coefficient of friction as test progressed. The jump of the friction force and seizure occurred after approximately 3300 seconds. The presence of seizure was confirmed from visual inspection of sample and counter sample. Textured sample contained circular oil pockets of pit area ratios of 3 and 13%,and depth between 15 and 20 µm. Textured discs did not lead to seizure. Traces of seizure on textured sample were not visible (Figure 2). Among textured discs sample with pit area ratio of 13% behaved better. DLC coating led to decrease in the coefficient of friction. The smallest variation of the friction force occurred for textured sample with pit area ratio of 13%. Other textured samples were also tested. It was found that laser surface texturing caused an increase in seizure resistance in lubricated reciprocating sliding. The results depend on parameters that characterize textured surface (diameter and pit area ratio). DLC coating led to a decrease in the coefficient of friction in conditions of high unitary pressure.
Slawomir WOS, Pawel PAWLUS (Rzeszow, Poland), Waldemar KOSZELA, Andrzej DZIERWA
12:40 - 13:00 #41066 - Evolution of the tire-road interface in relation to rubber layer deposition and tire-road wear particles presence.
Evolution of the tire-road interface in relation to rubber layer deposition and tire-road wear particles presence.

Following road engineering determinants of road safety and infrastructure longevity, research of tire-road interface focuses on friction and wear aspects of interface evolution. In road engineering, the interface evolution is traditionally depicted by the road aggregate polishing process. However, the surface coatings covering the aggregate and the presence of tire-road wear particles at the interface are often overlooked [1, 2]. To investigate these factors, a laboratory study was conducted using a tribometer with a pin-on-disk configuration. This study aimed to monitor the evolution of the friction coefficient during wear tests in a controlled environment [3, 4]. Mosaic disks were fabricated using granite, a common aggregate in road construction, and a softer limestone aggregate. A series of short-term tests were performed to examine the initial stages of surface alterations, including aggregate and rubber wear, rubber deposition on aggregate surfaces, and the generation of tire-road wear particles. Throughout the experiment, data on surface topography, friction coefficients, and mass loss of different system components were collected to elucidate the early stages of tire-road contact evolution. Morphological and compositional analyses of tire-road wear particles (TRWP) were conducted to assess the differential impact of various particle types on the friction coefficient. The study identified two primary phases in the friction coefficient curve: an initial increase followed by a continual decline after the peak. This behaviour was attributed not primarily to polishing but to the rubber layer's surface coating and the generation of interface wear particles. The presence of both the rubber layer and TRWP contributes to a reduction in the friction coefficient and wear rate, with distinct mechanisms associated with each third-body type. While the rubber layer masks microtexture and mediates sliding between surfaces, TRWP introduce a rolling element to the interaction. Comparing the collected wear particles revealed a similar composition and morphology to the particles collected on-road and generated in other laboratory settings reported by other researchers [5]. Our research illuminates the intricate interplay between the friction coefficient and the condition of the tire-road interface. It underscores the need to consider the deposition of the rubber layer and the presence of TRWP for their collective effect on the friction coefficient. This investigation advances the limited understanding of the texture-friction relationship by highlighting the significance of wear particle presence and surface coatings in enhancing road safety.
Minh-Tan DO (Nantes)

"Wednesday 29 May"

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13:00 - 14:00

Lunch Break


"Wednesday 29 May"

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14:00 - 14:40

Keynote Presentation 6

14:00 - 14:40 SMART Sensors for Sustainable Manufacturing. Cosimi CORLETO (STIL) (Keynote Speaker, Aix-en-Provence Cedex 3, France)

"Wednesday 29 May"

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D3-Session 3
14:40 - 16:00

Measurement, Instrumentation &Characterization in Metrology

Moderator: Jianxi LIU (Researcher) (Xi'an, China)
14:40 - 15:00 #39985 - Characterisation of SnO2 films prepared for different glass substrates by spectroscopic ellipsometry and ellipsometric data inversion.
Characterisation of SnO2 films prepared for different glass substrates by spectroscopic ellipsometry and ellipsometric data inversion.

This paper investigates the impact of ion infiltration of substrates on the optical properties of films. SnO2 films are prepared on silica-soda-lime (SL) and fused quartz (FQ) substrates by spin-coating method with the same growth parameters. The roughness of the films is characterised by atomic force microscopy (AFM). The compositions are determined by X-ray photoelectron spectroscopy (XPS). The physical properties, such as refractive index and extinction coefficient, are analyzed by spectroscopic ellipsometry (SE) with a single Tauc-Lorentz oscillator model in the wavelength range between 250-1000nm. Results show that the refractive index on FQ is more significant than that on SL, which may be caused by the metal ions of substrates. This phenomenon indicates that the substrate type affect the film's optical properties. In addition, the whale optimisation algorithm (WOA) is applied for the determination of thicknesses and refractive index of SnO2 in different substrates with transparent wavelength coverage (400nm-800nm), and it found that the results obtained by the WOA algorithm agree with those by SE well.
Liyuan MA (Xiamen, China), Changcai CUI, Tukun LI, Shan LOU, Paul SCOTT, Wenhan ZENG
15:00 - 15:20 #40018 - Facilitating metrology integration through the development of miniature nanophotonic-based sensors.
Facilitating metrology integration through the development of miniature nanophotonic-based sensors.

The manufacturing sector is consistently looking to move towards more smart and autonomous processes in order to reduce wastage and achieve ‘right first-time every-time’ outcomes. This requires sufficient real-time feedback from processes to correct errors during machining/build cycles. Achieving this is non-trivial and requires the proliferation of sensors integrated to provide ‘on-machine’ or ‘in-process’ measurement. The current size, weight and cost of conventional optical instrumentation is a significant barrier to realising this vision. While there have been ongoing efforts to realise small and lightweight instrumentation using conventional approaches these have seen limited success in general. However, recent developments in the areas of nanophotonics and metasurfaces means they now offer a path by which a step-change in these key sensor attributes can be achieved. Here, we discuss our recent work in this area, considering how metasurfaces can be utilised to both miniaturise and simplify optical systems. The flexible control of optical wavefronts passing through metasurfaces also potentially provides a path to implement techniques that, if realised using conventional glass elements could only be achieved using complex and difficult to manufacture freeform optical surfaces. Our recent work has looked at exploiting metasurfaces to create ultra-compact realisations of several optical techniques prevalent in surface and dimensional metrology, including confocal microscopy, chromatic confocal microscopy, spectroscopy and focus variation. However, the potential of this approach goes far beyond this. The metasurfaces implemented are of the truncated optical waveguide form, consisting of square arrays of GaN pillars having a fixed height of 750 nm and arranged with a centre-to-centre spacing of 450 nm. The radii of the pillars are varied to change the local phase delay that light experiences when passing through them. Circular pillars are used which minimise polarisation dependence which is advantageous for sensors detecting light reflected from unknown surfaces. A selection of the manufactured metasurfaces on an Al_2 O_3 substrate is shown in figure 1(a). The confocal sensor shown in figure 1(b) demonstrates how multiple functions can be combined in a single metasurface, interleaving pillars that deliver two different phase delays simultaneously allow the sensor to be realised with just the addition of a point light source and a point detector. The chromatic confocal sensor (CCS) shown in figure 1(c) utilises the chromatic aberration inherent in basic hyperbolic metalens designs to remove the need for groups of lenses or diffractive optical elements. In this realisation, the end of an optical fibre is used as the point source with the only additional element needed to realise the probe being the metalens. In addition, we have combined this with metalens-enhanced probe with a compact specklemeter. This device the analyses wavelength dependant speckle patterns, produced by a pseudo-randomized scattering medium consisting of femtosecond laser machined voids, to replace a conventional bulk optic spectrometer. This approach yields a CCS sensor with both the probe and the detection elements realised in an ultra-compact form. Finally, we describe a focus variation instrument that exploits the wavelength dependent focal plane of a simple metalens to determine topography using a ‘shape-from-focus’ approach without any mechanical scanning of elements, and a metasurface based spectrometer implemented by a metalens which combines dispersion and focussing functions in a single element. Summary: Nanophotonic elements, including photonic metasurfaces, offer a new path to the creation of ultra-compact instrumentation which can overcome the longstanding barriers present when using traditional approaches to optical sensor design. We show how they can provide a path to the development of a new generation of ultra-compact optical instrumentation which will underpin the necessary proliferation of on-machine optical sensors and support the development of more smart and autonomous manufacturing processes.
Daniel TOWNEND, Andrew HENNING (Hudderfield, United Kingdom), Justin Ho-Tin CHAN, Joseph KENDRICK, Pengqian (Jacob) YANG, James WILLIAMSON, Dawei TANG, Nityanand SHARMA, Haydn MARTIN, Xiang (Jane) JIANG
15:20 - 15:40 #38873 - Enhancing the potential of fringe projection measurement in L-PBF additive manufacturing.
Enhancing the potential of fringe projection measurement in L-PBF additive manufacturing.

Metallic-based additive manufacturing through Laser-Powder Bed Fusion (L-PBF) has gained significant attention across various sectors due to its capability to produce highly accurate, complex, and customised geometric parts [1, 2]. Consequently, addressing unexpected deviations from the intended geometry during the production process through post-processing operations becomes challenging, particularly for internal complex features. To address this limitation, in-process layer-based surface measurement methods are an active area of research to enable in-time corrective actions or process halts upon the identification of critical defects [1, 3–6]. Fringe projection (FP) [3, 7] has shown potential as a suitable measurement technique, owing to its high-resolution, non-invasive, and full-field surface topology measurement capabilities, facilitating defect detection. In the L-PBF process, FP measurements are typically implemented in a fully-closed confined machine chamber. This requires the proper integration of the measurement system with the existing machine setup to enable accurate measurement of the printed surface within the expected limits of accuracy and resolution, minimising errors. To fully exploit FP advantages for measuring surface topology in L-PBF, appropriate hardware choices regarding the measurement system are crucial. Additionally, the FP acquisition and reconstruction algorithms should be customised to realise the required measurement speed and accuracy. This study identifies factors significantly impacting measurement speed, accuracy and resolution, with emphasis on investigating the impact of hardware selection and related parameters. Simulations conducted using Unity and Solidworks software offer insights into depth of field, resolution, and field of view within a 1:1 scale mock-up chamber within an L-PBF machine (see Figures 1 and 2 for the design and FP simulation, respectively). This analysis enables the selection of suitable lens and aperture sizes, allowing to focus on the measurement area and reducing noise interference due to compact space of L-PBF chamber. Based on the hardware setup and simulation outcomes, an optimal depth of field is determined to ensure consistent fringe resolution across the target area. Furthermore, the gamma calibration plots signify the appropriate choice and application of fringe projection methods.
Tibebe YALEW (Nottingham,UK, United Kingdom), Qingkang BAO, Xiangjun KONG, Luke TODHUNTER, Gerardo ADESSO, Samanta PIANO
15:40 - 16:00 #40119 - Advancements in 3D Surface Characterization: Developing Novel Filtration Techniques for Complex Freeform Surfaces.
Advancements in 3D Surface Characterization: Developing Novel Filtration Techniques for Complex Freeform Surfaces.

Recent advancements in manufacturing technologies, notably in additive manufacturing, have enabled the production of complex freeform surfaces tailored to meet specific functional requirements. However, the precise measurement and characterization of these intricate surfaces pose significant challenges when using traditional methods. In our prior research, we established a comprehensive framework for characterizing freeform surfaces represented as 3D triangle meshes. This innovative approach allows for a complete assessment of 3D surface topography without compromising any data. Within this framework, we have also developed and validated a suite of 3D parameters. These parameters encompass various dimensions, including height, hybrid, volume, and feature-specific measurements. A critical aspect of 3D surface characterization is surface decomposition, which entails differentiating the surface texture from the foundational reference surface. This paper introduces our latest advancements in freeform surface filtration techniques essential for effective decomposition. We are currently developing four distinct types of filtration methods: (1) Laplacian Diffusion Filter: This functions similarly to the standard Gaussian filter but is tailored for lattice grid surfaces. It effectively smoothens the surface while maintaining its essential characteristics. (2) Improved Diffusion Filter with Anti-Shrinkage Properties: This innovative filter is adept for both dimensional analysis and surface texture assessment. Its anti-shrinkage feature ensures that the true nature of the surface is retained during the filtration process. (3) Feature-Preserving Diffusion Filter: Specifically designed for structured freeform surfaces, this filter maintains the integrity of distinct surface features while performing necessary filtration. (4) Morphological Filters: These versatile filters are capable of executing a range of operations, including morphological erosion, dilation, opening, closing, and sequential procedures. They are instrumental in refining the surface for detailed analysis. The paper will introduce these filtration methods and present preliminary results demonstrating their efficacy in the context of freeform surface characterization. This research marks a significant step forward in the precise analysis of complex surfaces, paving the way for more advanced applications in manufacturing and quality control.
Wenhan ZENG (Huddersfield, United Kingdom), Francois BLATEYRON, Shan LOU, Paul SCOTT, Xiangqian JIANG

"Wednesday 29 May"

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16:00 - 16:20

Coffee Break


"Wednesday 29 May"

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D3Session 3b
16:20 - 17:20

Measurement, Instrumentation &Characterization in Metrology

Moderator: Roberto SOUZA (Faculty) (Sao Paulo, Brazil, Brazil)
16:20 - 16:40 #40288 - Roughness road analysis by photometric computer vision system.
Roughness road analysis by photometric computer vision system.

The most recent technological advances in imaging technologies, including optical systems and algorithms, have been utilized to inspect (measure) roads and their surroundings. Such data enable road managers or local authorities to assess road safety. However, there is a need to explore a compromise between measurement time, metrological accuracy, transportability and the cost of the system used. In this study, an optimized process in terms of acquisition systems and algorithms is proposed to measure the roughness of the road microstructure and macrostructure. The photometric stereo technique, which estimates surface normals from a set of images observing the same scene under different light conditions, is employed [1-3]. As the appearance of the road can change depending on its formulation or age, a fast MLP algorithm is applied to model the reciprocal function of various BRDFs. Similarly, only six lights (LED with a diffuser) are positioned in a ring around the measured sample to limit acquisition time, and they are fixed to the camera to ensure the accuracy of their locations. Since the scale of microstructure variations is about 100 µm and a few millimeters for the macrostructure along the Z axis for a small part of the road, a lens with a long focal length is used to avoid optical distortions. The camera's cell sensor size is 3.45 x 3.45 µm, and the resolution is 4096 x 3000 for an acquired surface of size 146 x 109 mm. To avoid spatial demosaicing distortions, a matrix of 2 by 2 pixels from the Bayer filter is used to produce one color pixel. The resolution for axes X and Y is thus 71 µm, and the full system cost is less than 10 k€. Figure 1 presents the results obtained for these samples. The total time for acquiring images and computing roughness parameters according to ISO norm 4287 [2] from the 3D surface is less than 5 minutes with a standard laptop computer. The results obtained with our framework show a strong correlation between traditional surface roughness measurements and our measurements. Thanks to our process, a compromise is proposed between the price of the acquisition system, processing time, and spatial sampling. In the future, these initial results could be extended to color and glossiness evaluation because photometric stereo allows measuring the albedo of a surface simultaneously with its shape.
Benjamin BRINGIER, Majdi KHOUDEIR (Poitiers)
16:40 - 17:00 #40299 - Holistic calibration and non-uniform B-splines reconstruction framework of deflectometry.
Holistic calibration and non-uniform B-splines reconstruction framework of deflectometry.

Phase measuring deflectometry (PMD) is a potential measuring tool of optical surfaces, particularly for freeform surface measurement, owing to its high dynamic range, high sensitivity, high dynamic range, and high robustness. It is a gradient measuring tool, in which the correspondences between the camera and screen pixels are established based on their gray levels or phases. The normal directions at the measurement points can be deduced from the geometrical configuration and the law of reflection. Then the surface form of the surface under test (SUT) can be reconstructed by gradient integration. This paper addresses several key aspects, such as attaining high-precision calibration and reconstructing complex surface forms, and so on. Specifically, the measuring accuracy of PMD based on the geometric ray-tracing relies on the quality of system calibration. However, achieving high-precision calibration poses challenges. Traditional stepwise calibration methods can lead to error accumulation and amplification. Additionally, oversimplified imaging models and biases in numerical optimization contribute to calibration errors. Therefore, a holistic calibration method based on the holonomic framework priors (HCHFP), grounded in a thorough analysis of PMD uncertainty, is proposed to address the aforementioned issues by leveraging the associated physical constraints. Besides, independently modeling each ray, in conjunction with ray-tracing and imaging compensation, enhances the representational capacity. On the other hands, high-precision reconstruction by gradient integration is also challenging in PMD. Because most reconstruction algorithms are not well adapted to complex surface forms with local undulations, and a large number of tedious operations are demanded for calculating the ray intersections. Therefore, a general reconstruction framework is proposed based on the non-uniform B-spline (NUBS), which embeds the NUBS into the PMD framework to enhance the local representativity. And the correspondences between the points on the screen, camera and workpiece can be established by the parameter mapping instead of by the ray intersections, which reducing the complexity of the algorithm. Experimental results demonstrate that HCHFP can improve measurement accuracy by at least 38% compared to traditional approaches. And a general reconstruction framework based on NUBS achieves measurement precision at the hundred-nanometres for complex surface forms. Finally, measurement results of several typical optical components are presented, along with their relevant application scenarios. And it can find widespread applications in precision optical measurement.
Wei LANG (Shanghai, China), Xiangchao ZHANG
17:00 - 17:20 #40569 - A multi-laboratory comparison of surface texture parameters using coherence scanning interferometry and confocal microscopy.
A multi-laboratory comparison of surface texture parameters using coherence scanning interferometry and confocal microscopy.

As the manufacturing industry continues to evolve, so does the need to further improve the functionality of a manufactured part. Thus, the aim of a manufacturing process is not solely limited to the production of a part to fit its nominal design shape but also to modify its surface characteristics with the goal of increasing its performance. Knowledge of a part’s surface can provide insight into the manufacturing processes used to create it and, by understanding surface properties, we can potentially enhance the functionality of the surface under examination [1]. Looking at it from another perspective, 75 % of failures are determined in the early stages of a part’s development but are not detected until the later stages of production, due to limited feedback. Optical surface topography measuring instruments use the light scattered from a measured surface to reconstruct and obtain a height map of the surface. Then, the reconstructed height map can be used to determine the surface texture parameters of the measured surface. However, given the variability of measurement techniques between instruments, discrepancies are commonly observed in the outputs of different instruments. Inconsistencies are also detected when comparing optical with contact instruments. In many cases, the differences between instruments can be explained using critical assessment of the measured topographies, usually expressed in formal comparison exercises [2, 3]. The main outcomes of a comparison exercise are to establish traceability in the measurement and to compare and assess the outputs of different instruments. In contrast, the comparison exercise performed in this work was designed to establish a generic benchmark for the output of surface texture parameters from eleven participating laboratories. Several limitations were placed on each participant to restrict the impact of instrument related influence factors on the measured data and of different data processing methods. In detail, the measurement techniques considered were coherence scanning interferometry (CSI) and confocal microscopy. Further, the objective lens chosen had to cover a measurement area of at least (0.5 × 0.5) mm without stitching, with a minimum numerical aperture of 0.2. As for the measurements themselves, a robust protocol ensured that each participant was able to navigate to each measurement area with 1 the help of easily identifiable fiducials markers. Finally, data processing was solely carried out by the pilot laboratory and the participating laboratories were able to control and vary only the instrument and acquisition settings. Consequently, the variables on which the benchmark is based are the measuring instruments and their respective operators. The material measures measured, shown in figure 1, are a type profile periodic sinusoid (PPS) and type areal irregular (AIR). The analysis of the measured data involved levelling of the topographies followed by alignment and cropping of the supplied data using a co-localisation algorithm. The aforementioned instrument-related restrictions coupled with the strict application of the protocol’s guidelines resulted in minimum alignment shifts of the measured data in relation to the other participants’ measurements. Bandwidth matching was then performed using the appropriate Gaussian convolution S- and L-filters [4, 5].
Athanasios PAPPAS (Nottingham, United Kingdom)