Book

# Fundamental Principles of Engineering Nanometrology

Authors:

## Abstract

The principles of engineering metrology applied to the micro- and nanoscale: essential reading for all scientists and engineers involved in the commercialisation of nanotechnology and measurement processes requiring accuracy at the nanoscale.The establishment of common standards will be an essential key to unlocking the commercial potential of Micro- and Nanotechnologies (MNT), enabling fabrication plants to interchange parts, packaging and design rules. Effectively MNT standardization will provide the micro- and nanoscale equivalents of macro-scale nuts and bolts or house bricks. Currently there is a major thrust for standardization of MNT activities, with committees of the ISO, IEC and numerous national and regional committees being set up.In this book Professor Richard Leach, of the UK's National Physical Laboratory (NPL) makes a significant contribution to standardization in the field of MNT, extending the principles of engineering metrology to the micro- and nanoscale, with a focus on dimensional and mass metrology. The principles and techniques covered in this book form the essential toolkit for scientists and engineers involved in the commercialisation of nanotechnology and measurement processes requiring accuracy at the nanoscale.Key topics covered include: Basic metrological terminology, and the highly important topic of measurement uncertainty. Instrumentation, including an introduction to the laser Measurement of length using optical interferometry, including gauge block interferometry Displacement measurement and sensors Surface texture measurement, stylus, optical and scanning probe instruments, calibration, profile and areal characterisation Coordinate metrology Low mass and force metrologyAbout the AuthorProfessor Richard Leach is a Principal Research Scientist in the Mass & Dimensional Group, Engineering Measurement Division at the National Physical Laboratory (NPL), UK. Provides a basic introduction to measurement and instruments Thoroughly presents numerous measurement techniques, from static length and displacement to surface topography, mass and force Covers multiple optical surface measuring instruments and related topics (interferometry, triangulation, confocal , variable focus, and scattering instruments) Explains, in depth, the calibration of surface topography measuring instruments (traceability; calibration of profile and areal surface texture measuring instruments; uncertainties) Discusses the material in a way that is comprehensible to even those with only a limited mathematical knowledge. © 2010 Richard K. Leach Published by Elsevier Inc. All rights reserved.
... Surface metrology instruments based on optical techniques are considerably faster in terms of independent surface measurement points per unit time than those using a contact stylus, which involve mechanical raster scanning to measure a surface area [24]. Furthermore, the non-contact nature of optical instruments provides the benefit of avoiding the risk of damaging the measured surface [25]. ...
... tribological properties, fatigue resistance and heat transfer) [87,88]. The need to control and therefore accurately measure the surface topography becomes increasingly important as components and devices get smaller and more complex, in which case the surface topography features become key functional features of a component [25,83,87]. ...
... Furthermore, areal measurements have more statistical significance than equivalent profile measurements, merely because there are more data points [79]. Although profile measurement is well established and widely used in industry, the growing demand for manufactured components with tailored surface features for enhanced functionality is positioning areal measurement as a more useful approach to surface topography measurement [25]. [19]). ...
Thesis
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Additive manufacturing (AM) is increasingly being used to fabricate fully functional parts. In this scenario, tolerances for dimensions and surface finish become crucial, especially for applications with stringent requirements. Therefore, the measurement of AM parts is essential to ensure adequate performance and to inform the manufacturing process. Typical metal AM surfaces are highly irregular, exhibiting a large number of high aspect-ratio topographic features, deep recesses and loose particles, while polymer AM surfaces are often translucent or have low reflectivity. Because of these characteristics, it can be challenging for any surface measuring technique to accurately measure the topography of metal and polymer AM surfaces. Coherence scanning interferometry (CSI) is one of the most accurate methods for areal surface topography measurement. CSI uses an interferometric objective lens and spatially extended, spectrally broadband illumination. When scanning a surface along the optical axis through the focus of the interferometric objective lens, interference fringes will be visible only within a narrow surface height range, corresponding to the zero group-velocity optical path difference of the interferometer. This phenomenon is known as ‘low-coherence interference’ and provides a highly accurate non-contact sensing mechanism to determine the three-dimensional topography of a surface. CSI has the ability to measure a wide range of surface types, from optically smooth to rough, as well as discontinuous surfaces without the 2π ambiguity that can arise with single-wavelength, phase-shifting interferometry. However, due to the limited numerical aperture of the imaging system, CSI may suffer from poor signal-to-noise ratios when measuring high-slope angle topographic features and surfaces with significant texture, or more generally, surfaces with low reflectance, compromising the ability to reliably determine surface heights. Although previous CSI technologies have shown difficulties when measuring AM surfaces, recent progress in the development of CSI allows a significantly enhanced detection sensitivity through the use of advanced analysis techniques, such as filtering of the light source spectrum bandwidth, high dynamic range lighting levels, oversampling (i.e. adjusting the number of camera acquisitions over each interference fringe) and sophisticated topography reconstruction algorithms. In this thesis, the effects of the aforementioned advanced analysis techniques on the measurement of typical as-built metal AM surfaces covering various textures and slope distributions are empirically investigated and systematically analysed. Guidelines are provided for the optimisation of the measurement of metal AM surfaces by balancing the total data acquisition time, the size of the measurement area, and the percentage of measured data points (i.e. data coverage). The detailed surface topography information captured with CSI is essential for providing feedback to the manufacturing process and for quality control of AM products. To validate this, a challenging case study has been considered. The feasibility of ink-jet printing a transparent polymer of tetrafluoroethylene, hexafluoropropylene and vinylidene fluoride (known as THV) to produce films of a few nanometres to several micrometres in thickness has been assessed using CSI. Solutions to minimise the ‘coffee ring’ effect and the formation of undesired wrinkle-like features on the surface when ink-jet printing THV are demonstrated. This work contributes to the field of polymer AM by providing insight into how to control and optimise the quality of ink-jet printed parts with the aid of surface metrology. Reducing measurement noise in CSI is an important consideration when measuring AM surfaces, in particular when the ability to capture data is compromised by poor signal-to-noise ratios. This thesis contributes to the understanding of the workings of measurement noise reduction methods and compares their effects when measuring surface topography in the presence of environmental vibration. The results provide guidance for the reduction of error in surface measurement for AM surfaces, and could be applied in a wider range of applications. The knowledge developed in this research is relevant to the manufacturing and scientific communities as CSI technologies are increasingly applied to the measurement of complex surfaces and in environments that resemble production areas more than metrology laboratories.
... By controlling them, it is possible to increase the knowledge about materials science and industrial processes and to carry out continuous improvements. One particular field of interest is the study of surface texture, where interest in its characterization and control have increased dramatically recently [1][2][3]. A correct surface control can define the functionality of the product and affects performance and life service. ...
... There are a great number of surface topography measuring instruments. According to the literature, measuring instruments can be divided into three classes, depending on the type of measurement method [1,10]: ...
... For this reason, it has been necessary to use those methods with calibrated roughness comparison specimens or other measuring instruments to distinguish the surface texture [10]. Otherwise, areal measurements give a more realistic interpretation of the whole surface and are more statistically significant [1]. ...
Article
Full-text available
One of the most important fields of study in material science is surface characterization. This topic is currently a field of growing interest as many functional properties depend on the surface texture. In this paper the authors, after a short a review of different methods for surface topography characterization and the determination of the traceability problems that arise in this type of measurements, propose four different designs of material standards that can be used to calibrate the most common optical measuring instruments used for these tasks, such as measuring microscopes, metallurgical microscopes, confocal microscopes, focus variation microscopes, etc. The authors consider that the use of this type of standards (or others similar to them) could provide a step forward in assuring metrological traceability for different metrological characteristics that enables a more precise measurement of surface features with optical measuring instruments. In addition, authors expect that this work could lay the groundwork for the development of custom standards with specialized features tuned to gain a better metrological control when measuring specific geometrical surface properties
... Conventionally, the stylus profilometer serves as a standard method for surface roughness measurement [17,18]. The stylus tip physically senses the sample surface and traverses across the surface at a constant speed with a static measuring force of 0.75 mN according to ISO 3274 [5]. ...
... The vertical movement of the stylus arm on the pivot is converted to a rotation of the diffraction grating and generate a frequency shift of the diffracted beams. Finally, the position of the stylus can be calculated from the phase of the interference signal generated by superimposing the diffracted beams [17,21,22]. Figure 1 illustrates the typical optical structure of a single-point confocal system. ...
... The spatial resolution is limited by the stylus tip size and shape, which can be as small as 0.1 µm [11]. However, the main drawback of the stylus measurement method is attributed to the damage to the measured surface due to the applied contact force [17]. In addition, the stylus tip and the PGI transducer are often too sensitive to be used in a manufacturing environment for in-situ measurement [18]. ...
Article
Full-text available
The characterization of surface topographic features on a component is typically quantified using two-dimensional roughness descriptors which are captured by off-line desktop instruments. Ideally any measurement system should be integrated into the manufacturing process to provide in-situ measurement and real-time feedback. A non-contact in-situ surface topography measuring system is proposed in this paper. The proposed system utilizes a laser confocal sensor in both lateral and vertical scanning modes to measure the height of the target features. The roughness parameters are calculated in the developed data processing software according to ISO 4287. To reduce the inherent disadvantage of confocal microscopy, e.g., scattering noise at steep angles and background noise from specular reflection from the optical elements, the developed system has been calibrated and a linear correction factor has been applied in this study. A particular challenge identified for this work is the in-situ measurement of features generated by a robotized surface finishing system. The proposed system was integrated onto a robotic arm with the measuring distance and angle adjusted during measurement based on a CAD model of the component in question. Experimental data confirms the capability of this system to measure the surface roughness within the Ra range of 0.2–7 μm (bandwidth λc/λs of 300), with a relative accuracy of 5%.
... Therefore the extent to which profile parameters approximate areal parameters should be assessed on a variety of surfaces. This paper will focus on the R a parameter (equations 1a and 1b) and its areal equivalent, S a (equations 2a and 2b) [6,7,8]. Both parameters are the arithmetic mean average absolute deviation from the mean height of the surface, but have some fundamental differences due to the use of profile or areal filters [8]. ...
... This paper will focus on the R a parameter (equations 1a and 1b) and its areal equivalent, S a (equations 2a and 2b) [6,7,8]. Both parameters are the arithmetic mean average absolute deviation from the mean height of the surface, but have some fundamental differences due to the use of profile or areal filters [8]. Alternative measures which better characterise and descriminate surfaces can be used [2,9]. ...
... In this study bothR a and S a were calculated over the same distance or area; however, if the lengths or areas are different this will influence the reported values, especially on surfaces with multi-scale features [2]. Leach comments that R a should be measured over "a number of consecutive sampling lengths" with users reporting the average value [8]. ...
Article
Direct comparison of areal and profile roughness measurement values is not advisable due to fundamental differences in the measurement techniques. However researchers may wish to compare between laboratories with differing equipment, or against literature values. This paper investigates how well the profile arithmetic mean average roughness, $R_a$, approximates its areal equivalent $S_a$. Simulated rough surfaces and samples from the ETOPO1 global relief model were used. The mean of up to 20 $R_a$ profiles from the surface were compared with surface $S_a$ for 100 repeats. Differences between $\bar{R_a}$ and $S_a$ fell as the number of $R_a$ values averaged increased. For simulated surfaces mean % difference between $\bar{R_a}$ and $S_a$ was in the range 16.06% to 3.47% when only one $R_a$ profile was taken. By averaging 20 $R_a$ values mean % difference fell to 6.60% to 0.81%. By not considering $R_a$ profiles parallel to the main feature direction (identified visually), mean % difference was further reduced. For ETOPO1 global relief surfaces mean % difference was in the range 52.09% to 22.60% when only one $R_a$ value was used, and was 33.22% to 9.90% when 20 $R_a$ values were averaged. Where a surface feature direction could be identified, accounting for reduced the difference between $\bar{R_a}$ and $S_a$ by approximately 5% points. The results suggest that taking the mean of between 3 and 5 $R_a$ values will give a good estimate of $S_a$ on regular or simple surfaces. However, for some complex real world surfaces discrepancy between $\bar{R_a}$ and $S_a$ are high. Caveats including the use of filters for areal and profile measurements, and profile alignment are discussed.
... Form and surface texture definitions and measurements are discussed in detail elsewhere (for example, surface form in [93] and surface texture in [287] and [186]). The main types of artefacts available are described below. ...
... In principle, the effect can be calculated if the optical constants are well known, and corrected if the surface is of a single material. However, experience shows that prediction is not accurate enough and specific experimental investigation is usually carried out (e.g., the so-called "stack method" to measure the phase shift at the surface [186]). In all cases, the uncertainty of the correction must be accounted for (see e.g., [74]). ...
Article
Dimensional measurements play a central role in enabling advanced manufacturing technologies, enhancing the quality of products and increasing productivity. This role becomes even more important in the context of Industry 4.0, where reliable and accurate digital models of products, processes and production systems are needed. To establish the traceability chain that links measurements in production to the length unit, dimensional artefacts-ranging from measurement standards to calibrated workpieces-are fundamental. The paper examines dimensional artefacts, discussing their characteristics, availability and role in supporting production by establishing metrological traceability, and provides guidelines for their selection, use and development.
... Its value depends on whether most of the material is located above (negative skewed) or below (positive skewed) the mean line. On the other hand, the kurtosis parameter is related to the sharpness of the surface height distribution, and it is very sensitive to occasional high peaks or deep valleys [41,42]. The kurtosis (Sku) and skewness (Ssk) for the treated surfaces as function of the laser power for the experiments in Series 1 including the reference sample are illustrated in Fig. 3b and 3c, respectively. ...
Article
Full-text available
To obtain a good adhesive bonding quality between aluminum parts it is necessary to remove contaminations and to define the chemical composition and topographic status of the corresponding surfaces. Hence, a surface pre-treatment is needed which simultaneously guarantees environmental concerns, industrial safety, efficiency, and reproducibility of surface quality. For this purpose, nano-second-pulsed laser processing is suitable, especially concerning the integration of the surface pre-treatment process in the main processing line of the body shop. To fulfill the technical requirements and to minimize the production of scrap parts, an online monitoring and control system of the pre-treatment process is essential. In this study, electromagnetic radiations, which are generated by the laser-based pre-treatment process, are detected online using photodiodes. The recorded signals are examined in terms of the correlation between their dynamics, the resulting surface state (quality of the pre-treatment) and the executed process/system parameters. Conventional offline methods for analyzing the chemical composition and topography of surfaces are applied to validate the results. It was found that the obtained information can be used to define a process window and enable the development of a proper process monitoring and control system for the laser-based pre-treatment process for industrial use.
... The other challenge is associated with the measurement bandwidth limitation of different measurement techniques. The distinct volumetric measurement ability of XCT and the size of the voxel makes it difficult to match the bandwidth of operation of the 2D or 2½D traceable surface texture instruments [11,43]. The typical voxel size of XCT is in the range of micrometres to a couple of hundreds of micrometres compared to the nanometres order vertical resolution and sub-micrometre lateral resolution of traditional roughness measurement instruments, limiting XCT's ability to measure high spatial frequencies [44]. ...
Article
Metal additively-manufactured (AM) parts are increasingly used as safety-critical components in industry. Surface textures of metal AM parts are different to conventionally machined surfaces and can directly influence the functional performance of the parts. However, it is difficult or impossible to access and measure non-line-of-sight AM surfaces by conventional measurement techniques. X-ray computed tomography (XCT) is a promising technique that can measure non-line-of-sight surfaces non-destructively. However, the metrology framework for XCT to evaluate surface texture of AM parts is yet to be fully established, and there is a lack of development in surface texture reference standards that fit the purpose. In this paper, we have established a route to calibrate XCT for AM surface texture evaluation using a prototype three-dimensional roughness standard (3DRS) developed by the National Physical Laboratory that has a range of AM surface texture features and was designed for compatibility between 2D (profile), 2½D (areal), and tomography measuring instruments. A measurement protocol has been established between XCT and the contact stylus system, and uncertainty evaluation of 3DRS surface texture was established.
... A standard Gaussian filter (8 µm) was applied to the profiles in order to separate waviness and roughness. In order to compare the variation in the ridge morphology during growth, we calculated standard line roughness parameters, namely Rc (mean height), Rsm (mean spacing), Ra (arithmetic mean height) [47], and the aspect ratio of the ridges defined as AR = Rc/Rsm. ...
Article
Full-text available
The plant cuticle is a multifunctional barrier that separates the organs of the plant from the surrounding environment. Cuticular ridges are microscale wrinkle-like cuticular protrusions that occur on many flower and leaf surfaces. These microscopic ridges can help against pest insects by reducing the frictional forces experienced when they walk on the leaves and might also provide mechanical stability to the growing plant organs. Here, we have studied the development of cuticular ridges on adaxial leaf surfaces of the tropical Araceae Schismatoglottis calyptrata. We used polymer replicas of adaxial leaf surfaces at various ontogenetic stages to study the morphological changes occurring on the leaf surfaces. We characterized the replica surfaces by using confocal laser scanning microscopy and commercial surface analysis software. The development of cuticular ridges is polar and the ridge progression occurs basipetally with a specific inclination to the midrib on Schismatoglottis calyptrata leaves. Using Colorado potato beetles as model species, we performed traction experiments on freshly unrolled and adult leaves and found low walking frictional forces of insects on both of these surfaces. The changes in the micro-and macroscale morphology of the leaves should improve our understanding of the way that plants defend themselves against insect herbivores. 1326
... 25 Also, there is a need for atomic-scale methods in 3D films surfaces investigation and in trying to link atomic-scale observations with macroscopic continuum models and experimental results, particularly concerning structure, energetics, dynamics, transport, and thermodynamics processes. 26,27 The 3D surface topography of thin films possesses only statistical self-similarity, which takes place only in a restricted range of the spatial scales. 10 In our previous work, we have studied the surface properties of Al incorporated c-Si and/or homogeneous c-Si layer (such as absorber layer for solar cell) produced at low temperature by a selective way of ion beam irradiation followed by chemical etching in the light of fractal and multifractal concept. ...
Article
The tunable surface properties of Al‐incorporated c‐Si and/or homogeneous c‐Si (i.e., absorber layer) thin films are investigated with the help of 3D surface topography, statistical analysis, and contact angle measurement. The absorber layers are developed by ion irradiation on c‐Al/a‐Si films, which results the crystallization of Si in bilayer films, and the top unreacted Al layers were chemically etched off by wet selective etching. The 3D surface topography and statistical analysis is performed on the atomic force microscopy images of the absorber film surface. The analyses suggest that the surfaces are highly complex and irregular isotropic. The surface roughness and irregularity is found to be decreasing with increasing ion fluence. Variation of contact angle with statistical parameters suggest that the wettability of the absorber surface strongly depends on the surface statistical parameters. The surfaces are hydrophobic in nature, and hydrophobicity is found to decrease with increasing ion fluence. The hydrophobic nature of low reflective absorber surface suggests that the film may be useful as a photon absorber layer for advance solar cell applications.
... maximum surface height is similar to the profile height. Some optical methods, such as scattering, allow one to determine the Sq parameter [23]. The random Gaussian surface is modeled on the basis of the Sq parameter [24][25][26][27][28]. Wu [24] modified the surface model of surface with Gaussian probability distribution and assumed main wavelength. ...
Article
Full-text available
Areal 3D analysis of surface texture gives more opportunities than a study of 2D profiles. Surface topography evaluation, considered as 3D dimensional analysis in micro or nanoscales, plays an important role in many fields of science and life. Among many texture parameters, those connected with height are the most often used. However, there are many other parameters and functions that can provide additional important information regarding functional behaviour of surfaces in different applications. The knowledge about the functional importance of various surface properties is low. This review tries to fill this gap. Surface texture parameters are presented in various groups: height, spatial, hybrid, functional, feature, and others. Based on experiences of the present authors and literature review, the relationships among various surface parameters and functional properties are described. A proposal of a selection of parameters on the basis of their functional significations is provided. Considerations for future challenges are addressed.
... Typical properties of high-precision translatory measuring devices achieved in the state of the art[13][14][15][16] ...
Article
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Nanomeasuring machines developed at the Technische Universität Ilmenau enable three-dimensional measurements and manufacturing processes with the lowest uncertainties. Due to the requirements for these processes, a highly reproducible and long-term stable tool changing system is needed. For this purpose, kinematically determined couplings are widely used. The state-of-the-art investigations on those are not sufficient for the highest demands on the reproducibility required for this application. A theoretical determination of the reproducibility based on analytical or numerical methods is possible, however not in the desired nanometer range. Due to this, a measurement setup for the determination of the reproducibility in five degrees of freedom with nanometer uncertainty was developed. First, potential measuring devices are systematically examined and measurement principles were developed out of this. A three-dimensional vector-based uncertainty analysis is performed to prove the feasibility of the measurement principle and provides a basis for further design. As a result, a translatory measurement uncertainty of 10 nm and a rotatory uncertainty of 11 nrad can be reached. Afterwards, the measurement setup is designed, focusing on the metrological frame and the lift-off device. The developed setup exceeds the uncertainties of the measurement setups presented in the state-of-the-art by an order of magnitude, allowing new in-depth investigations of the reproducibility of kinematic couplings.
... Most current technologies for the inspection and verification of form are centred around the measurement and manipulation of point cloud surface data. Tactile CMSs sample surfaces at specific locations using contact probes, optical CMSs are typically capable of high-density point-based sampling of surfaces within line-of-sight [26]. X-ray computed tomography performs volumetric sampling of density, but surfaces can be extracted via thresholding and often sampled into point-based representations [27]. ...
Article
In this work an approach to investigate measurement uncertainty in coordinate metrology is presented, based on fitting Gaussian random fields to high-density point clouds produced by measurement repeats. The fitted field delivers a depiction of the spatial distribution of random measurement error over a part geometry, and can incorporate local bias information through further measurement or with the use of an external model to obtain a complete, spatial uncertainty map. The statistical model also allows the application of Monte Carlo simulation to investigate how error propagates through the data processing pipeline ultimately affecting the determination of features of size and the verification of conformance to specifications. The proposed approach is validated through application to simulated test cases involving known measurement error, and then applied to a real part, measured with optical and contact technologies. The results indicate the usefulness of the approach to estimate measurement uncertainty and to investigate performance and behaviour of measurement solutions applied to the inspection and verification of industrial parts. The approach paves the way for the implementation of automated measurement systems capable of self-assessment of measurement performance.
... A value of Rsk > 0 means the presence of sharper peaks and larger valleys and a value of Rsk < 0 means the presence of blunt peaks with sharper valleys. For a detailed scientific background of the roughness parameters, the interested reader is referred to any standard textbook on engineering metrology [35]. For ease of comparison, the mean aspect ratio (AR = Rc/Rsm) was defined to characterize and compare the changes in ridge dimensions and the effect on insect adhesion. ...
Article
Full-text available
Cuticular ridges on plant surfaces can control insect adhesion and wetting behaviour and might also offer stability to underlying cells during growth. The growth of the plant cuticle and its underlying cells possibly results in changes in the morphology of cuticular ridges and may also affect their function. We present spatial and temporal patterns in cuticular ridge development on the leaf surfaces of the model plant, Hevea brasiliensis. We have identified, by confocal laser scanning microscopy of polymer leaf replicas, an acropetally directed progression of ridges during the ontogeny of Hevea brasiliensis leaf surfaces. The use of Colorado potato beetles (Leptinotarsa decemlineata) as a model insect species has shown that the changing dimensions of cuticular ridges on plant leaves during ontogeny have a significant impact on insect traction forces and act as an effective indirect defence mechanism. The traction forces of walking insects are significantly lower on mature leaf surfaces compared with young leaf surfaces. The measured walking traction forces exhibit a strong negative correlation with the dimensions of the cuticular ridges.
... The conventional method for surface finish measurement is to scan surfaces with a contact stylus and capture surface height deviations in the form of a surface profile. However, stylus-based method is susceptible to environmental disturbance due to its contact nature and it is a relatively slow process attributed to the point-to-point measuring mode and the risk of 'stylus flight' [6]. Hence, it is not a suitable technique for in-situ surface finish measurement. ...
Article
Full-text available
Surface roughness is an important characteristic which affects the quality, performance and lifetime of many types of industrial products, ranging from mechanical and biomedical parts to semiconductors and optics. In recent years, in-situ measurement for surface roughness is increasingly demanded to provide real-time feedback and reduce systematic errors of realignment and repositioning during manufacturing. Commercially available instruments, such as stylus profilometer, confocal laser scanning microscope and coherence scanning interferometer, are limited to a relatively low measurement speed and difficult for in-situ measurement. In this paper, an in-house developed surface measuring system using chromatic confocal sensor was integrated into a mass finishing cell to perform in-situ and non-contact surface roughness measurement. The surface roughness parameters are calculated and evaluated according to ISO 4287 and ISO 4288. From the preliminary experiments, it was verified that the relative error of surface roughness measurements can be kept within 5%.
... The importance of effective industrial measurement solutions to provide accurate and traceable parts is widely acknowledged [1,2]. Hence, it is vital for the continued progress of rapidly emerging manufacturing technologies, such as additive manufacturing, that we continue to develop new and improved measurement technologies in order to meet the increasing measurement demands [3]. ...
Article
The performance of measurement or manufacturing systems in high-precision applications is dependent upon the dynamics of the system, as vibration can be a significant contributor to the measurement uncertainty and process variability. Technologies making use of accelerometers and laser vibrometers are available to rapidly measure and process structural dynamic data but the software infrastructure is yet to be available in an open source or standardised format to allow rapid inter-platform use. In this paper, we present a novel condition monitoring system, which uses commercially available accelerometers in combination with a control-monitoring infrastructure to allow for the appraisal of the performance of a measurement or manufacturing system. A field-programmable gate array (FPGA)-based control system is implemented for high-speed data acquisition and signal processing of six triaxial accelerometers, with a frequency range of 1 Hz to 6000 Hz, a sensitivity of 102.5 mV/ms−2 and a maximum sample rate of 12,800 samples per second per channel. The system includes two methods of operation: real-time performance monitoring and detailed measurement/manufacturing verification. A lathe condition monitoring investigation is undertaken to demonstrate the utility of this system and acquire typical machining performance parameters in order to monitor the “health” of the system.
... For example for grinding [Chen et al. (2017)] and coating [Ching et al. (2014)], it is desired to measure the surface properties with nanometer resolution. For this purpose, high-precision instruments such as atomic force microscopes (AFMs) [Leach (2014)] need to be operated in the line. However, they are typically sensitive to floor vibrations, requiring vibration isolation for high quality surface measurement [Eaton and West (2010)]. ...
Article
This paper proposes a sample-tracking vibration isolator based on hybrid reluctance actuators to bring a vibration sensitive instrument toward inline metrology. The hybrid reluctance actuators vertically move the platform to mount the instrument and maintain its position with respect to the target sample, rejecting floor vibrations. For compensating crosstalk motions due to manufacturing and assembly tolerances, the actuator forces are balanced, demonstrating a reduction by a factor of about 10 for frequencies below 70 Hz. In order to regulate the moving platform motion, a feedback controller is designed achieving a closed-loop bandwidth of 260 Hz. Experiments reveal that the proposed vibration isolator reduces the vibrations (RMS value) from 37.5nm to 1.6 nm and consequently realizes nanometer positioning resolution in a vibrational environment. These experiments successfully demonstrate the effectiveness of the proposed vibration isolator and the capability of the hybrid reluctance actuators to handle floor vibrations.
... Contact based techniques (i.e. stylus profilometer) are not suitable for mirror finish surface measurement because the stylus tip may scratch the surface [6]. For mirror finish surface measurement, optical techniques such as confocal microscope, coherence scanning interferometer and phase shifting interferometer have great potential due to their non-contact mechanism to avoid both surface damage and contamination. ...
Conference Paper
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Mirror finish surface products are widely used in many industries such as aerospace, optics, semiconductor and biomedical device manufacturing. The surface texture of mirror finish products is usually measured by off-line instruments such as coherence scanning or phase shifting interferometers. However, most commercial interferometers are expensive and must be operated in a clean and vibration-free laboratory environment. In order to achieve both in-situ surface quality control and automated tool changing for the polishing process, fast and non-contact surface texture measurement are required. To address these in-situ measurement challenges, a surface texture measuring system based on fringe pattern illumination method is proposed in this paper. By analyzing the lumi-nance contrast ratio of the fringe pattern reflection image and comparing to the measurement results from the referenced coherence scanning interferometer, the experimental results showed that the proposed system was able to measure different mirror finish surfaces with Sa and Sq values in the range of 15 nm to 120 nm and 30 nm to 160 nm respectively. In addition, the luminance contrast ratio was also correlated with directions of the machining marks and the projected fringes at different measurement angles. The surface texture aspect ratio parameter Str which provides information about the strength of the machining marks was experimentally evaluated and compared with luminance contrast change. In conclusion, the proposed measuring system was able to measure surface texture with a relative error less than 10% at measurement angle between 20° to 160°, and indicate machining pattern effects on the mirror finish surface.
... Although, Sa parameter is common and widely evaluated parameter for characterizing surface roughness of a sample, it doesn't provide enough information about the shape of the surface deviations. For instance, the surfaces have similar Sa values may have different form of deviations [14]. The Sq parameter is the root mean square height of the surface deviations. ...
Chapter
Additive manufacturing (AM) has great potential on manufacturing both polymer and metal parts as final product. However, optimization of surface texture quality has not been fully achieved yet. AM surfaces present variable textures that differs according to the AM methods and process parameters. Because of their unusual texture, it is important to evaluate surface properties of metal and polymer parts produced by different AM processes. In this study, it is aimed to define 2D and 3D surface texture of poly-lactic acid (PLA) polymer and AlSi10Mg metal parts manufactured by Fused Deposition Modelling (FDM) and Direct Metal Laser Sintering (DMLS) respectively. ISO 4287 Ra, Rq and Rz profile roughness parameters were defined by tactile method while ISO 25178 Sa, Sq and Sz areal parameters were measured by optical method. Measurements were taken from up-skin and down-skin of the samples which were in 30 mm diameter and 4 mm thickness. Results were evaluated within themselves and literature studies. Differences between profile and areal surface characterization and need of new specifications were also discussed.
... Reconstruction of the three-dimensional surface is carried-out by scanning through the z-axis and using the intensity of light at each pixel to identify the surface height at that point (Artigas, 2011;Leach, 2010). The resulting scan produces a three-dimensional image of the surface, calibrated to ISO 25178 for the measurement of surface texture. ...
Article
Full-text available
The use of surface metrology microscopes to quantify surface texture is a powerful tool for the analysis of archaeological materials. Data collected from these microscopes allows for reliable and reproducible measurements of surface characteristics. However, archaeological materials provide some unique challenges for microscopic analysis, including archaeological objects that cannot leave museums or are too large to observe under a microscope. Because of these challenges, many researchers create molds and casts of an artifact's surface prior to measuring surface texture. The replicate surface is assumed to be an accurate representation of the original surface texture; however, limited testing has been done on the reliability of different molding compounds. This paper uses confocal microscopy to test the fidelity of different molding compounds for surface texture measurements. Results suggest that the objects' original surface texture can pose challenges to the accuracy of molds and the resulting casts, and that the intrinsic texture of the molding material impacts surface measurements of the replicated object.
... The difference is on the use of the CMM itself. CMM is an instrument that provided with the probing system that moving in order to DOI [7]. The application of this CMM structural design been applied to the 3-axis PCB drilling machine. ...
Article
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This paper presents the investigation on design efficiency of two different 3-axis printed circuit board (PCB) drilling machine products using Boothroyd Dewhurst design for manufacturing and assembly (DFMA) approach. The two products that are used as a case study named machine A and machine B products. The investigation also intends to analyze on the total operation time, and total parts of the two existing machine products. A comparative study was done for both products that give better results for machine A in term of design efficiency and total operation time compared to machine B. However, the total parts of machine A is still higher than machine B. Therefore, the modified machine A is proposed to improve the design efficiency by minimizing the total parts of machine A. The Boothroyd Dewhurst DFMA technique is then utilizedd to analyze the proposed modified machine A. As results, the design efficiency of the proposed modified machine A improves from 5.81% to 9.24%.
... Optical measuring devices (confocal, white light interferometer, structured light, focus variation) can typically be used only for measurements orthogonal to the surface as they are used for roughness measurement or measurement of small distances. For a detailed overview of coordinate measurement devices, especially µCMMs, we refer to [4], [5]. ...
Article
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Highly accurate measurements of small structures are challenging in many applications. An example is the optimization of the hole geometry in fuel injectors. Due to the small size of the structure, tactile approaches are insufficient while standard optical measurement systems cannot provide data on complex geometries. In this paper, a new purely optical 3D micro-coordinate machine – the µCMM of Alicona and its accuracy by determining the maximum permissible translatory and stationary error is presented. Moreover, we demonstrate that the focus variation principle allows 3D measurements of such small components by presenting the measurement and evaluation of micro injection holes.
... Optical measuring devices (confocal, white light interferometer, structured light, focus variation) can typically be used only for measurements orthogonal to the surface as they are used for roughness measurement or measurement of small distances. For a detailed overview of coordinate measurement devices, especially µCMMs, we refer to [4], [5]. ...
Conference Paper
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Highly accurate measurements of small structures are challenging in many applications. An example is the optimization of the hole geometry in fuel injectors. Due to the small size of the structure, tactile approaches are insufficient while standard optical measurement systems cannot provide data on complex geometries. In this paper, a new purely optical 3D micro-coordinate machine – the μCMM of Alicona and its accuracy by determining the maximum permissible translatory and stationary error is presented. Moreover, we demonstrate that the focus variation principle allows 3D measurements of such small components by presenting the measurement and evaluation of micro injection holes.
... Results show a general improvement in measurement quality when magnification is increased from 5× to 20×, i.e. reduced bias with respect to the CSI reference dataset and reduced repeatability error, but a significant decrease from 20× to 50×. This quality decrease is likely to be a result of an increase in the noise present in volumetric reconstructions, as shown in figure 3. Out-of-field-of-view artefacts [41] will contribute towards the increase in noise present in the 50× case, though noise also increased between the 5× and 20× setups. This noise increase is most likely as a result of a slight decrease in contrast with an increase in magnification, as the X-ray flux per unit volume through the sample increases with magnification [9]. ...
Article
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Recent studies have shown that X-ray computed tomography (XCT) can be used to measure the surface topography of additively manufactured parts. However, further research is necessary to fully understand XCT measurement performance. Here, we show how magnification of the X-ray projections and resolution of the volumetric reconstruction grid influence the determination of surface topography in the XCT data processing pipeline. We also compare XCT results to coherence scanning interferometry (CSI) measurements and find that by increasing the magnification of the X-ray projections, smaller topographic detail can be resolved, approaching the lateral resolution of CSI. Results show that there is an optimum setting for magnification, below and above which XCT measurement performance can degrade. The resolution of the volumetric reconstruction grid has a less pronounced effect, but in general, adopting higher or lower resolutions than the default leads to degraded repeatability in surface determination. The problem of determining sensitivity of XCT surface measurement as a function of setup parameters is complex, and it is not yet possible to provide optimal setup configurations that work regardless of object geometry. However, the methods presented here, as well as the results obtained, represent a useful contribution to good practice for XCT measurement of surfaces.
... Conventionally, measuring instruments for shape and texture are independently developed; for example, a high-accuracy coordinate measuring machine (micro-CMM) has been developed for three-dimensional measurement and coherent scanning interferometry (CSI) and point auto-focus microscopes have been developed for determining surface textures [6]. However, there are no established instruments for multi-scale coordinate measurements. ...
Article
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Recent advancement of fabrication technologies enables nanoscale surface patterning on microstructures, which requires multi-scale measurements for the determination of their geometric dimensions and surface texture in the same coordinate system. Previously, we have developed a micro-coordinate measuring machine with a laser-trapped microprobe that uses an optically trapped microsphere as a surface detecting sensor. In this paper, we propose a surface imaging technique using the optically trapped microsphere as a micro-lens, i.e., the surface imaging system is integrated into the coordinate measuring system. The optically trapped microsphere with a diameter of 8 μm was brought close to a measured surface to image the surface underneath it. Because there is an unknown gap between the microsphere and surface, the focal plane of the imaging system had to be adjusted to the measured surface by the developed imaging lens system. With the microsphere-based imaging system, an optical diffractive grating of sub-micrometer periodic structure with 417 nm pitch and 50 nm depth was successfully imaged and the defect on the grating was detected. Thus, we verified that development of an imaging system based on the optically trapped microsphere for multi-scale evaluation systems can be accomplished.
... Individual 0.8 Â 0.8 mm measured areas were automatically stitched to generate a 14 Â 3 mm topography, which was then analyzed using the TalyMap software supplied by the equipment manufacturer. Initially, the cylindrical form of the surfaces was removed, followed by the application of a "denoising" filter (also called S-Filter) aimed at removing short-scale components (the so-called "microroughness") usually associated with instrument or environmental noise [21,22]; Robust Gaussian filter with 4x pixel size cut-off was adopted for microroughness removal. The reason for applying a "denoising" filter was to eliminate unrealistic geometrical artifacts that could disturb the convergence of the numerical solution. ...
Article
The tribological performance of piston ring-cylinder bore was investigated through deterministic mixed-lubrication modeling. Bore topographies measured from regular honed Grey Cast Iron (GCI) to “Mirror-Like” coated bore surfaces were used in the investigation. In contrast with typical honed GCI bores composed of relatively well-distributed peaks and valleys, coated bores are composed of a much smoother plateau and localized deep pores. Simulation results indicated that coated bore surfaces generate significantly higher hydrodynamic pressure and lower asperity contacts when compared with regular GCI topographies. The influence of roughness filtering and the associated cut-offs values were also considered in the analysis, showing that the choice of cut-off affects both the predicted hydrodynamic and asperity contact pressures. Furthermore, the simulation results also revealed that most of the fluid pressure was generated by the honing grooves rather than by the localized pores present on coated bore surfaces.
... As manufactured parts get more complex, tolerances get tighter and the need for accurate control of surface texture becomes more prominent [1]. Surface texture parameters facilitate surface control by assigning the surface a quantitative value, calculated via a series of mathematical operations [2,3], that enable comparisons to be made with other surfaces, surfaces to be specified on engineering drawings and functional information to be quantified [4,5]. ...
Article
Results of an international survey are presented, detailing the use of surface texture parameters in industry. The survey received 179 responses from a total of 34 countries, revealing the use of a variety of parameters from ISO 4287, ISO 12085, ISO 13565-2/3 and ISO 25178-2. The survey responses show an increase in the number of users of profile parameters, and an increase in the range of surface texture parameters used, compared to the results from a similar survey in 1999, as well as a significant uptake of the new areal surface texture parameters. Individual sector usage is also discussed.
... Common techniques for characterization of the height of grating structures include atomic force microscopy (AFM) and confocal microscopy [19] (see Fig. 1). Measurements using these techniques have been obtained in this study to compare the different techniques. ...
Article
With new fabrication methods for mass production of nanotextured samples, there is an increasing demand for new characterization methods. Conventional microscopes are either too slow and/or too sensitive to vibrations. Scatterometry is a good candidate for in-line measuring in an industrial environment as it is insensitive to vibrations and very fast. However, as common scatterometry techniques are nonimaging, it can be challenging for the operator to find the area of interest on a sample and to detect defects. We have therefore developed the technique imaging scatterometry, in which the user first has to select the area of interest after the data have been acquired. In addition, one is no longer limited to analyze areas equal to the spot size, and areas down to 3 μm×3 lm can be analyzed. The special method Fourier lens scatterometry is capable of performing measurements on misaligned samples and is therefore suitable in a production line. We demonstrate characterization of one-dimensional and two-dimensional gratings from a single measurement using a Fourier lens scatterometer. In this paper, we present a comparison between spectroscopic scatterometry, the newly developed imaging scatterometry, and some state-of-the-art conventional characterization techniques, atomic force microscopy and confocal microscopy.
... As shown in Figure 1, during lateral scanning, movement of the stylus reflects the surface fluctuation and is tracked by a high-resolution displacement sensor. Typical resolution of a traditional structure with a stylus tracked by an inductive transducer is around 10 nm [12], while some newly developed systems using phase interferometric technology are able to achieve sub-nanometer resolution [13]. In this study, Taylor Hobson PGI 800 is used as a representative model of latest stylus profilometry. ...
Conference Paper
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Surfaces made by Additive Manufacturing (AM) processes normally show higher roughness and more complicated microstructures than conventional machined surfaces. In this study, AM surface roughness measurements using both tactile and optical techniques are analyzed, theoretically and experimentally. Analytical results showed both techniques have comparable performance when measuring AM samples with good surface integrity. For surfaces with steep features, coherence scanning interferometry showed more reliable performance especially when peak-to-valley value was required. In addition of the benchmarking study, development of a low-cost measurement system, using laser confocal technology, is also presented in this paper. By comparing the measurement results with those from a coherent scanning interferometer, accuracy levels of the proposed system can be evaluated. It was concluded that with comparable accuracy, the proposed low-cost optical system was able to achieve much faster measurements, which would make it possible for in-situ surface quality checking.
... Surface characterization was performed using a white light interferometer, described in detail in [16], and 10x objective lens. Using white light interferometry to analyze a very rough surface is a challenge due to difficulty in achieving null fringe condition (perfect leveling of the sample surface being measured). ...
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The development of additive manufacturing has allowed for increased flexibility and complexity of designs over formative and subtractive manufacturing. However, a limiting factor of additive manufacturing is the as-built surface quality as well as the difficulty in maintaining an acceptable surface roughness in overhanging structures. In order to optimize surface roughness in these structures, samples covering a range of overhang angles and process parameters were built in a laser powder bed fusion system. Analysis of the surface roughness was then performed to determine a relationship between process parameters, angle of the overhanging surface, and surface roughness. It was found that the analysis of surface roughness metrics, such as Rpc, Rsm, and Rc, can indicate a shift between surfaces dominated by partially melted powder particles and surfaces dominated by material from the re-solidified melt track.
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Data fusion enables characterisation of an object using multiple datasets collected by various sensors. To improve optical coordinate measurement using data fusion, researchers have proposed numerous algorithmic solutions and methods. The most popular examples are Gaussian process (GP) and weighted least-squares (WLS) algorithms, which depend on user-defined mathematical models describing the geometric characteristics of the measured object. Existing research on GP and WLS algorithms indicate that GP algorithms have been widely applied in both academia and industry, despite their use being limited to applications on relatively simple geometries. Research on WLS algorithms is less common than research on GP algorithms, as the mathematical tools used in the WLS cases are too simple to be applied with complex geometries. Machine learning is a new technology that is increasingly being applied to data fusion applications. Research on this technology is relatively scarce, but recent work has highlighted the potential of machine learning methods with significant results. Unlike GP and WLS algorithms, machine learning algorithms can autonomously learn the geometrical features of an object. To understand existing research in depth and explore a path for future work, a new taxonomy of data fusion algorithms is proposed, covering the mathematical background and existing research surrounding each algorithm type. To conclude, the advantages and limitations of the existing methods are reviewed, highlighting the issues related to data quality and the types of test artefacts.
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The angle and shape of lithic tool edges have long been used as a method of inferring prehistoric tool function. However, accurately measuring and characterizing edge angles of lithic tools is notoriously difficult. Studies using goniometers, calipers, or morphometrics often rely on two-dimensional representations of edges. Furthermore, there have been limited attempts to quantitatively document stone tool edges based on surface metrology, most notably edge curvature. In this study, we use microCT to capture models of the complex geometry, or ‘freeform’ surfaces, of experimental quartzite flakes from Olduvai Gorge (Tanzania) to document and mathematically calculate edge curvature using multiscalar length-scale analysis. Through this analysis, we also explore the quantification of re-entrant (overhang) features on lithic edge cross-sections. On lithic tools, especially coarse-grained rocks with complex surface topographies, such as quartzite, traditional techniques for edge angle measurement are incapable of capturing re-entrant features on edge profiles. Here we present the first archaeological study that addresses the measurement of these re-entrant features, using novel length-scale and curvature analysis methods of calculating edge angles for complex freeform surfaces. With these new methods for measuring edge angles, we can consider the impact of complex geometry, including re-entrant features, on the function of lithic tools in the past.
Article
This article focuses on the inference on the errors in manufactured parts controlled by using measurements devices. The characterization of the part surface topographies is core in several applications. A broad set of properties (tribological, optical, biological, mechanical, etc.) depends on the micro‐ and macrogeometry of the parts. Moreover, parts usually show typical deterministic geometric deviation pattern, referred to as manufacturing signatures, due to the specific manufacturing processes and process setup parameters adopted for their production. In several situations, the measurements may also be affected by systematic errors due to the measurement process, that might be caused, for example, by a poor part alignment during the measurement process. Measurement techniques and characterization methods have been standardized in the International Standard ISO 25178, defining parameters characterizing the surface topography and supplying methods and formula adapt to deal with this issue computationally. In the present article, we consider a type of spatial dependence between measured values at different points that suggest the use of the variogram to identify patterns in the parts. We offer a comparison, based on a real set of measures, between the latter approach and the conventional as a test of the efficient performance of our findings.
Article
In this paper, we proposed a new device for geometry errors measurement and coaxiality evaluation, and the corresponding methodology for coaxiality evaluation from measurement data is presented, which allows to characterize multiple holes at a time. Unlike traditional measurement system a laser sensor is mounted onto out of the holes so that multi-hole surfaces can be “seen” by the senor when it rotates around a fixed axis. First the intersections (or ellipse profiles) of the sensor’s scanning plane and holes, are computed by fitting. Then, the center coordinates and profile points of the ellipse are computed and transformed to the 3D global coordinate frame. Finally the centerline of the hole is determined from the 3D profile points by using a weighted least-squares fitting algorithm. In addition, to reduce the effect of noises on the measurement result, error analysis and compensation techniques are studied to improve the measurement accuracy. A case study is presented to validate the measurement principle and data processing approach.
Chapter
In this chapter, a general survey is first done on the micropitting damage of spur and helical gears, which manifests itself to the roughness scale. The mechanism that trigger this type of damage as well as the characteristics that distinguish it from those typical of macropitting (the classical pitting) are described. The problem to be solved for a reliable calculation procedure of micropitting load carrying capacity of gears are then analyzed and, to this end, the ideal characteristics of a general micropitting model are described. An interesting tribological-dynamic analytical model for cylindrical spur gears is then described, which also consists of a three-dimensional analytical-numerical contact sub-model and a multiaxial fatigue sub-model. The procedure for calculating the surface durability of spur and helical gears in accordance with the ISO standards is described, highlighting when deemed necessary how the formulae used by the same ISO are anchored to the theoretical bases previously discussed. Finally, for a better understanding of micropitting mechanisms, attention is drawn to the need to introduce, instead of traditional profile parameters, the areal field parameters that best describe the topography and texture of surfaces.
Article
Resolution is a key criterion in 6 degrees of freedom (DOF) precision positioning systems such as Gough Stewart platforms. Nevertheless, there is no consensus on the definition of resolution and its evaluation. We propose a resolution characterisation method for the 6 DOF precision positioning systems based on users’ requirements (in telescope and synchrotron fields). The method is founded on two user-specific criteria: stability and increment motion length. A new measurement system based on capacitive sensor technology has been developed to assess resolution. The uncertainty of our measurement system was estimated by the Monte Carlo method. This system enables measurement of hexapod platform displacement along 6 DOF with nanometre uncertainty. This is a considerable advantage because it is possible to carry out all the measures of resolution along 6 DOF automatically and without setup modification. We evaluated the resolution of an hexapod specifically developed for the Eastern Anatolia Observatory. The 6 DOF contactless measuring system enabled us to demonstrate an hexapod resolution of 20 nm for translation and 0.25 µrad for rotation.
Conference Paper
Photogrammetry based systems are able to produce 3D reconstructions of an object given a set of images taken from different orientations. In this paper, we implement a light-field camera within a photogrammetry system in order to capture additional depth information, as well as the photogrammetric point cloud. Compared to a traditional camera that only captures the intensity of the incident light, a light-field camera also provides angular information for each pixel. In principle, this additional information allows 2D images to be reconstructed at a given focal plane, and hence a depth map can be computed. Through the fusion of light-field and photogrammetric data, we show that it is possible to improve the measurement uncertainty of a millimetre scale 3D object, compared to that from the individual systems. By imaging a series of test artefacts from various positions, individual point clouds were produced from depth-map information and triangulation of corresponding features between images. Using both measurements, data fusion methods were implemented in order to provide a single point cloud with reduced measurement uncertainty.
Article
We describe bistatic scattering measurements on eight reference targets constructed from Al <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> O <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> grit of various sizes embedded in an absorptive epoxy matrix. These samples' surface topographies were measured using focus-variation microscopy, and their autocorrelation lengths and root-mean-square (RMS) roughness levels were extracted. Bistatic scattering measurements were then performed in the principal plane over the 325-500 GHz range and at 650 GHz, using either a vector network analyzer or a narrow band source and detector, respectively, in both sand ppolarizations, and at incidence angles of 25°, 45°, and 65°. The samples' RMS roughness levels cover the range of 36-280 μm, corresponding to 0.040 <; σ/λ <; 0.60. Their autocorrelation lengths cover the range of 0.086 <; L/λ <; 1.14, generally shorter than the samples in most previous studies. The measurements of bidirectional reflectance distribution function (BRDF) include regimes of both diffuse scattering and specular reflectance. The measurements were compared to two ab initio rough-surface scattering theories: the modified integral equation method (IEM-B) and the Generalized Harvey-Shack (GHS) model. There are no adjustable free parameters in these comparisons, but other important shortcomings exist and are described for both theories. Although there are several individual cases where either the IEM or the GHS theory (or both) provide an excellent match to measurement, their overall agreement with measurement across the entire dataset is poor. In addition, the diffuse BRDF in each bistatic scan has been fitted to a Lambertian (constant) dependence on scattering angle, and a purely empirical model has been developed for the dependence of the Lambertian scattering on frequency, roughness, polarization, and incidence angle. Across the entire dataset, this empirical model provides the best match to measurement, and can be used for reliable phenomenology studies of submillimeter imaging or wireless telecommunication.
Chapter
Fused deposition modeling is a proven technology, widely diffused in industry, born for the fabrication of aesthetic and functional prototypes. Recently used for small and medium series of parts and for tooling, it received particular attention in order to integrate prototyping systems within production. A limiting aspect of this technology is the obtainable roughness and above all its prediction: No machine software and Computer-Aided Manufacturing implements a relationship between process parameters and surface quality of components. The prediction of the surface properties is an essential tool that allows it to comply with design specifications and, in process planning, to determine manufacturing strategies. Recently, great effort has been spent to develop a characterization of such surfaces. In this chapter, prediction models are presented and a new characterization approach is detailed. It is based on the theoretical prediction of the geometrical roughness profile, thus allowing it to obtain, in advance, all roughness parameters.
Chapter
The ability to produce complex, high-precision, miniature components is key to the transition to high-value manufacturing. The advanced manufacturing industries, using precision machining techniques, such as diamond turning, injection moulding, micro-milling and micro-electro-discharge machining, currently have a number of capabilities for measuring small-scale structures with micro-scale tolerances, either with tactile or non-tactile systems. Metrology is essential for the reduction of dimensional tolerances, which allows the production of more efficient machines and the improvement of their longevity by reducing play or wear. In this chapter, contact and non-contact techniques that can be used to measure 3D features on the micro-metre scale are reviewed.
Thesis
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Actuellement, les pièces de formes complexes sont réalisées par des procédés de plus en plus automatisés, à l'aide de machines outil à 5 axes ou de robots. Le processus de fabrication s'appuie sur la définition d'une gamme de fabrication et se décompose en différentes étapes à partir de la définition du cahier des charges. À chacune de ces étapes, des écarts géométriques entre la forme souhaitée et la forme obtenue peuvent apparaître. La surveillance des procédés de fabrication est donc nécessaire, nécessitant même une mesure à 100% des pièces produites lors de la phase de la stabilisation du processus. Ainsi, mes travaux portent sur maîtrise de la qualité des surfaces produites en vue d'améliorer le procédé de fabrication. Ainsi, la définition des paramètres de la stratégie de fabrication est un élément déterminant dans le processus de fabrication. La première partie de mes travaux est consacrée à l'amélioration de la prédiction de la topographie des surfaces générées par le procédé d'usinage. Un autre aspect des travaux sur l'amélioration de la qualité des surfaces concerne l'intégration des opérations de contrôle au sein du moyen de production, afin de réaliser une mesure dite in- situ. Enfin, la dernière partie des travaux réalisés ont pour objectifs de proposer des stratégies de numérisation minimisant le nombre de configurations capteur et la quantité de données acquises tout en contrôlant la qualité.
Article
Good correlations between three-dimensional surface analyses of laser-beam-melted parts of nickel alloy HX and their mechanical properties were found. The surface analyses were performed with a confocal microscope, which offers a more profound surface data basis than a conventional, two-dimensional tactile profilometry. This new approach results in a wide range of three-dimensional surface parameters, which were each evaluated with respect to their feasibility for quality control in additive manufacturing. As a result of an automated surface analysis process by the confocal microscope and an industrial six-axis robot, the results are an innovative approach for quality control in additive manufacturing.
Chapter
This chapter introduces some of the concepts used in the measurement and characterisation of surface texture that will be used throughout the rest of the book. A short history of optical measurement techniques will be given, followed by descriptions of surface profile and areal surfaces. How surface texture sits within the ISO Geometrical Product Specification is discussed along with the current position with surface texture specification standards. Non-optical and optical surface texture measurement instrument types are summarised and some general advice is given on instrument choice.
Chapter
A point autofocus instrument is a non-contact surface texture measuring instrument that consists of an autofocus microscope and a high precision xy scanning stage. A point autofocus instrument is capable of measuring various surfaces with different surface properties, such as reflectivity, colour and slope angle, with high resolution and high accuracy. This chapter presents the basic principles of point autofocus instruments, their instrumentation, use and good practice, the limitations of the technique, and extensions of the basic principles, e.g., to allow the measurement of aspherical surfaces with a data stitching method.
Chapter
The increased use of areal surface topography measuring instruments in the past ten years has led to a range of optical instruments being developed and becoming commercially available. Such instruments make use of sophisticated mathematical algorithms to process the raw height information and transform it into topography data that are used for visualisation and calculation of areal surface texture parameters. Optical areal surface topography measuring instruments are powerful and flexible tools of a complex design, which makes them difficult to calibrate. Because the calibration process is an essential part of quality control during production it is very difficult for an industrial user to exploit the benefits of these instruments. This chapter endeavours to provide some guidance on calibrating optical areal surface topography measuring instruments according to the ISO 25178 suite of specification standards on areal surface topography measurement. Mainly the calibration of the geometrical characteristics of the instruments is discussed with the addition of some brief comments on the effect of filtration and areal surface texture parameters calculation.
Chapter
This chapter presents a number of terms and definitions that are common to the instruments presented in Chap. 5 to Chap. 12. The most common forms of optical aberration are described followed by a discussion of microscope objective lenses. The concepts of magnification, numerical aperture, lateral resolution, spot size and depth of field are discussed in limited detail to allow the reader to use them throughout the rest of the book.
Article
The mean square height, slope, and curvature are characteristics of roughness microgeometry that govern the performance of real surfaces in elastic contact. The values of these quantities deduced from stylus profile traces are distorted by the nonlinear filtering effect of the finite stylus tip and by the failure, at high enough tracing speeds of the stylus to maintain contact with the profile being traced. The development of a simulation model for assessing the magnitude of this distortion as well as the effect of record length and sampling frequency with tracing profiles that are realizations of a radom process having a specified spectrum are described. Illustrative parametric runs of the model are discussed.