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Correlating motif analysis and morphological filters for surface texture analysis
Abstract
In contrast to the mean-line based evaluation system, motif analysis and morphological filters are two techniques oriented to the characterization of functional properties of surfaces. The motif combination procedure is consistent with the functionality of the morphological closing filter that insignificant peaks on the profile are suppressed. By linking the functionality of the structuring elements with motif combination criterions, morphological envelopes are computed efficiently. Reversely the morphological closing filter coupled with horizontal line-segment structuring elements with lengths equivalent to the motif limits for roughness and waviness provides an alternative for motif analysis. The proposed morphological method has a sound mathematical basis and is stable. An example of applying the empirical motif method (ISO 12085) and the morphological method is demonstrated. The motif parameters resulted from two methods reveal that they coincide with each other. Thus two distinct function oriented methods for surface texture evaluation are technically correlated by mutual exploitation.
... The stylus method is incapable of detecting re-entrant features [6,141,157] and application to complex geometries is restricted by instrument and measurement requirements. The accurate alignment of measurements (direction of individual measurements, parallelity of multiple profiles in same direction) for the applied handheld Mituyoto SJ210 is hardly possible. ...
In the past decades, additive manufacturing (AM) has evolved from a rapid prototyping technology to a mature manufacturing process, offering significant advantages for lightweight design and specialized applications. Surface quality is crucial for the qualification of metal AM parts, particularly for load-bearing aerospace applications. Surface quality from a laser powder bed fusion (LPBF) AM process is typically characterised by agglomerations of attached powder particles, spatter, and weld or layer tracks, influenced by material, powder properties, build direction, and other factors. This work aims to provide a more comprehensive understanding and holistic description of LPBF surface quality, its formation, characterisation, and role in part functionality, using novel approaches and advanced optical measurement techniques.
The thesis is divided into three parts: "Measurement and Data Post-processing," "Surface Texture and Mechanical Properties," and "Areal Surface Features."
The first part discusses the application of optical measurements and related challenges for as-built and post-processed LPBF surfaces. Current industry practices use stylus contact measurements yielding 2D profiles, which are inadequate for LPBF's complex surface structures. Areal measurements, such as confocal microscopy and fringe projection, offer better surface coverage, reproducibility, and prevent surface damage. The transition from 2D to 3D parameters and from contact stylus to non-contact optical methods is proposed for comprehensive surface data.
The second part suggests describing AM surfaces in terms of part functionality, introducing surface texture parameters from the material ratio curve for fatigue performance, instead of traditional 2D parameters like Rt and Ra. Parameters like Svk, derived from the surface height distribution, relate well to fatigue failure modes in LPBF parts. Optimised processing parameters can achieve surface and mechanical properties comparable to post-processed and conventionally manufactured parts, potentially eliminating the need for surface post-processing.
The third part focuses on process-related surface texture characterisation, advancing functionality-based descriptions. It proposes using the particle size distribution of the processed metal powder to set pruning thresholds for feature segmentation, instead of ISO 25178's extreme value Sz. A novel approach to feature-based segmentation is developed.
These advancements will make AM more accessible and sustainable, broadening its application across various sectors with specialised functionality requirements.
... The historical basis of morphological filters was laid by mechanical filtration with probe devices and a Motif method [25]. S. Lu et al. [26] showed that the motif combination procedure is in good agreement with the results of the morphological closing filter. In this case, minor profile peaks are suppressed. ...
The scope of multifunctional surfaces in mechanical engineering and instrumentation is constantly expanding. Examples are products with multilayer coatings, products made of composite materials or using additive manufacturing technologies. A feature of multifunctional surfaces is two levels of texture with different parameter values. Various types of filters are used to decomposition and then analyze texture components. Traditionally, for such problems, a robust Gaussian regression filter and a morphological filter are used. The advantage of the morphological filter lies in the lower computational complexity and the ease of removing the shape component from the profile. This research presents generalized analysis of various types of an asymmetric morphological filter based on simulation. The asymmetric filter differs from the standard morphological filter by using different nesting indexes for combinations of morphological opening and closing operations. We have designed a compositional model of profile, which is superposition of two Gaussian distributions with different parameters and waviness. Relative filtering error of the arithmetic mean heights Ra was chosen as evaluation parameter. Based on the Monte Carlo experiments technique, the relative errors of the filters are determined. The main result of the research is algorithm for choosing nesting indexes depending on the type of primary profile. Thus, we give scientifically justified choice of the filter type and its task-specific parameters for applied use. The choice of filter type and two different nesting indexes in accordance with the developed algorithm provide relative error with a coverage interval less 3 % for 95 % coverage probability. The asymmetric morphological filter is effective for scale space analysis of surfaces with significant shape errors and waviness. The results obtained can be used to analyze the tribological properties of multifunctional surfaces of products.
... The stylus method is incapable of detecting re-entrant features [17,56,77] and application to complex geometries is restricted by instrument and measurement requirements. The accurate alignment of measurements (direction of individual measurements, parallelity of multiple profiles in same direction) for the applied handheld Mituyoto SJ210 is hardly possible. ...
Additive manufacturing technologies enable lightweight, functionally integrated designs and development of biomimetic structures. They contribute to the reduction of material waste and decrease in overall process duration. A major challenge for the qualification for aerospace applications is the surface quality. Considering Ti-64 laser powder bed fusion (LPBF) parts, particle agglomerations and resulting re-entrant features are characteristic of the upper surface layer. Wet-chemical post-processing of the components ensures reproducible surface quality for improved fatigue behaviour and application of functional coatings. The 3D SurFin® and chemical milling treatments result in smoother surface finishes with characteristic properties. In order to characterise these surfaces, three methods for surface texture measurement (contact and non-contact) were applied, namely confocal microscopy, fringe projection and stylus profilometry. The aim of this work was to show their suitability for measurement of laser powder bed fusion as-built and post-processed surfaces and compare results across the evaluated surface conditions. A user-oriented rating of the methods, summarising advantages and disadvantages of the used instruments specifically and the methods in general, is provided. Confocal microscopy reaches the highest resolution amongst the methods, but measurements take a long time. The raw data exhibit large measurement artefacts for as-built and chemically milled conditions, requiring proper data post-processing. The stylus method can only capture 2D profiles and the measurement was restricted by particle agglomerations and craters. However, the method (process and instrument) is entirely standardised and handheld devices are inexpensive, making it accessible for a large group of users. The fringe projection method was the quickest and easiest regarding measurement and data post-processing. Due to large areal coverage, reproduction of location when performing repeat measurements is possible. The spatial resolution is lower than for confocal microscopy but is still considered sufficiently high to characterise the investigated surface conditions.
... It was found that the application of wavelets can be classified as a manufacturing signature [40]. Furthermore, the use of morphological filters [41,42] with open and closing operations can also be very valuable [43][44][45]. ...
Errors that occur when surface topography is measured and analysed can be classified depending on the type of surface studied. Many types of surface topographies are considered when frequency-based errors are studied. However, turned surface topography is not comprehensively studied when data processing errors caused by false estimation (definition and suppression) of selected surface features (form or noise) are analysed. In the present work, the effects of the application of various methods (regular Gaussian regression, robust Gaussian regression, and spline and fast Fourier Transform filters) for the suppression of high-frequency measurement noise from the raw measured data of turned surface topography are presented and compared. The influence and usage of commonly used available commercial software, e.g., autocorrelation function, power spectral density, and texture direction, which function on the values of areal surface topography parameters from selected (ISO 25178) standards, are also introduced. Analysed surfaces were measured with a stylus or via non-contact (optical–white light interferometry) methods. It was found that the characterisation of surface topography, based on the analysis of selected features, can be crucial in reducing measurement and data analysis errors when various filters are applied. Moreover, the application of common functions can be advantageous when feature-based studies are proposed for both profile and areal data processing.
... Different filtering techniques have been standardized in surface metrology [16]. The most common digital filtering techniques are the envelope filter [17], the Gaussian filter [18], the Gaussian regression filter [19], the spline filter [20] and the wavelet filter [21]. International standards describe these filters, their parameters and provide guidance on the use, including ISO 25178 [22], ASME B46.1 [23] and ISO 16610 [24]. ...
Filtering is a required task in surface metrology for the identification of the components relevant for automated quality control. The calculation of real-time features about the surface is crucial to determining the mechanical and physical properties of the inspected product. The computation efficiency of the filtering operations is a major challenge in surface metrology, as current sensors provide massive volumes of data at very high acquisition rates. To overcome the challenges, this work presents different real-time filtering solutions comparing the performance on the CPU and on the GPU, using modern hardware. The proposed framework is focused on filtering techniques that can be expressed using a finite impulse response (FIR) kernel that includes the Gaussian kernel, the most common filtering technique recommended by ISO and ASME standards. This research work proposes variations of the double FIFO and double circular filters. The filters are transformed into a series of general matrix to matrix multiplications, which can be run extremely efficiently on different architectures. The proposed filtering approach provides superior performance compared with previous works. Additionally, tests are carried out to quantify the performance of the GPU in terms of data transfer and computation capabilities in order to diminish the penalty imposed by data transfer from main memory to the GPU in real-time operations. Based on the results, an efficient batch filtering technique is proposed that can be run on the GPU faster than the CPU even for small profile and kernel sizes, offloading this task from the host CPU for optimal system and application response.
... This leads to the filtration/ neglection of the geometrical form and waviness from the measured surface profiles, thus changing the texture appearance and the calculated parameter values. For the calculation of the actual contact area, this approach might not be the most reliable since the filtered roughness profiles only provide a part of the information about the contact (Lou et al., 2013a;Lou et al., 2013b), see Figure 2. Table 3 summarizes some examples of previously used samples, their surface measurement approach, and considered texture parameters. ...
A surface texture can be subdivided into three categories based on the magnitude of its wavelengths, i.e., macro-geometrical form, waviness, and roughness (from largest to smallest). Together, these components define how a surface will interact with the opposing surface. In most ice tribology studies, <2% of the entire sample surface is topographically analyzed. Although such a small percentage of the entire surface area generally provides statistically relevant information, the missing information about the texture complexity on a larger scale might reduce the possibility of accurately explaining the resulting tribological behavior. The purpose of this study was to review the existing surface measurement methods related to ice tribology and to present a holistic approach towards surface topography measurements for ice tribology applications. With the holistic surface measurement approach, the entire sample surfaces are scanned, and the measured data is analyzed on different magnitude levels. The discussed approach was applied to sandblasted steel samples which were afterward tested on two different ice tribometers. The experimental results showed that additional information about the sample surface topography enabled a better understanding of the ice friction mechanisms and allowed for a more straightforward correlation between the sample surface topography and its ice friction response.
... Segmentation of profile features is mainly described in two standards: ISO 4287 for profile elements, used to calculate RSm and Rc, and ISO 12085 for profile motifs, used to calculate R&W parameters. These methods are commonly criticised for their unstability, although they provide valuable results when used in an adequate context [25]. A new profile segmentation based on watersheds is now introduced in ISO 21920-2 and ISO 16610-45, adapted from areal segmentation [ISO 25178-2, [22]. ...
Segmentation of profile features is mainly described in two standards: ISO 4287 for profile elements, used to calculate RSm and Rc, and ISO 12085 for profile motifs, used to calculate R&W parameters. These methods are commonly criticised for their unstability, although they provide valuable results when used in an adequate context. A new profile segmentation based on watersheds is introduced in ISO 21920-2 and ISO 16610-45, on the model of areal feature parameters [Blateyron 2013], with the hope to solve most of the existing problems. However, there are very few comparisons between these methods and almost no recommendations for the configuration of the segmentation. This paper discusses the validity of applying segmentation methods on certain profiles and proposes a validity criterion. It also introduces a new method to determine an Optimal Limit A for the Motifs method. Finally, it investigates algorithmic differences between the watershed segmentation and the classical Motifs method, compares the results between the two methods, and suggests a guideline of good practices.
... Motif analysis was successful in characterizing functional properties of surfaces, especially in friction and contact problems [12][13][14]. In those studies, parameters were used both to identify and separate anisotropic components by appropriate anisotropic filtering and characterization of surface motifs. ...
Anisotropy can influence surface function and can be an indication of processing. These influences and indications include friction, wetting, and microwear. This article studies two methods for multiscale quantification and visualization of anisotropy. One uses multiscale curvature tensor analysis and shows anisotropy in horizontal coordinates i.e., topocentric. The other uses multiple bandpass filters (also known as sliding bandpass filters) applied prior to calculating anisotropy parameters, texture aspect ratios (Str) and texture directions (Std), showing anisotropy in horizontal directions only. Topographies were studied on two milled steel surfaces, one convex with an evident large scale, cylindrical form anisotropy, the other nominally flat with smaller scale anisotropies; a µEDMed surface, an example of an isotropic surface; and an additively manufactured surface with pillar-like features. Curvature tensors contain the two principal curvatures, i.e., maximum and minimum curvatures, which are orthogonal, and their directions, at each location. Principal directions are plotted for each calculated location on each surface, at each scale considered. Histograms in horizontal coordinates show altitude and azimuth angles of principal curvatures, elucidating dominant texture directions at each scale. Str and Std do not show vertical components, i.e., altitudes, of anisotropy. Changes of anisotropy with scale categorically failed to be detected by traditional characterization methods used conventionally. These multiscale methods show clearly in several representations that anisotropy changes with scale on actual surface measurements with markedly different anisotropies.
... Extraction of some texture features by morphological filtering methods [20,21] was often proposed and correlated with various commonly-used procedures, e.g. motif [22]. Analyses were performed for both 3D (surface) [23] and 2D (profile) [24][25][26] assessments. ...
In this paper both envelope approach and morphological filters for characterisation of surface textures were proposed, applied and thoroughly examined. Obtained results were compared with those received after appliance of commonly-used algorithms. The effect of appliance of proposed procedures on surface topography parameters (from ISO 25178 standard) was taken into consideration. The following types of surface textures were assessed: two-process plateau-honed cylinder liners, plateau-honed cylinder liners with additionally burnished dimples, turned piston skirts, grinded and/or isotropic topographies. It was assumed that envelope characteristics (envelope filtration) can provide results useful for assessments of deep and/or wide oil-reservoirs especially when they are edge located. Moreover, some near-valley areas of surface texture details can be less distorted when envelope filtering is accomplished. It was also found that closing and/or opening envelope filtration can be valuable for reduction of some surface topography measurement errors
... Many different digital filtering methods have been proposed. The most commonly used are the envelope filter [17], the Gaussian filter [18], the Gaussian regression filter [19], the spline filter [20] and the wavelet filter [21]. Most of these methods are also included in international standards such as ISO 25178 [22], ASME B46.1 [23] and ISO 16610 [24], which also provide guidance on the use of these filters. ...
Surface metrology in automated quality inspection is a field, among many others, affected by noise and thus requiring filtering. In surface metrology, filtering is required to remove undesired information from data in order to extract surface features and relevant properties necessary for quality control. Moreover, filtering requires immediate results, while the product is being manufactured. This way, quick correcting actions can be directly applied to solve possible manufacturing issues. This work proposes different strategies to filter height maps in real-time acquired using laser profilers, the most widely used inspection method in industrial applications. Different models to apply the filtering operations are considered, particularly assessing different alternatives to store previous samples in memory, which are required for data filtering. FIFO, double FIFO, circular and double circular buffers are evaluated. Furthermore, CPU parallelism, SIMD instructions and cache-line friendly data structures are analyzed. The proposed methods are extremely efficient, capable of filtering laser profiles at extremely high acquisition rates. The proposed methods are designed for real-time surface metrology, but they are very likely to find potential applications in different areas. The filters are compared in terms of accuracy and speed, including other well-known filters such as the spline filter. Tests analyze execution time, including cache efficiency and filtering accuracy. Results with synthetic data and real data obtained from steel strips show excellent performance, providing accurate results at very high speeds.
... Morphological filters are other types of nonlinear filters that can be used to suppress the outliers in measurement data. By moving spherical or flat structuring elements across measurement data, morphological closing operation can remove the pierces, and in opposite morphological opening operation can suppress the spikes [35]. Podulka et al. [36] presented an example of using a morphological closing filter with two sizes of flat structuring element to detect the spikes on a cylinder liner profile. ...
In comparison to tactile sensors, optical techniques can provide a fast, non-destructive profile/areal surface measurement solution. Nonetheless, high measurement noise, unmeasured points and outliers, are often observed in optical measurement, particularly for structured surfaces. To alleviate their detrimental impacts on the characterization of surface topography as well as the examination of micro/nanoscale geometries, a post-processing filtering technique, i.e. the clustering filter, which is essentially an iterative process to find the aggregation center of a cluster of points, is implemented. The clustering filter is particularly useful for noises and outlier suppression for optical measurement of structured surfaces due to its edge-preserving capability. Five surface samples with structured features are measured by an in-house developed dispersive interferometer and a commercial white light interferometer, thereafter the measured surface data is filtered by the clustering filter. Both noise and outliers are suppressed, which not only facilitates the visualization and characterization of surface topography, but also enables the accurate evaluation of local functional geometries.
... Hao et al. combined wavelet analysis and the watershed method, proposed feature-based surface characterization parameters, and studied their effect on friction characteristics [15]. Lou et al. studied the surface topography characterization problem based on the motif and pointed out the complementary effect of this method and the characterization based on midline surface topography [16]. ...
In order to explore the relationship between the surface topography parameters and friction properties of a rough contact interface under fluid dynamic pressure lubrication conditions, friction experiments were carried out. The three-dimensional surface topography of specimens was measured and characterized with a profile microscopy measuring system and scanning electron microscope. The friction coefficient showed a trend of decreasing first and then increasing with the increase in some surface topography parameters at lower pressure, such as the surface height arithmetic mean Sa, surface height distribution kurtosis Sku, surface volume average volume Vvv, and surface center area average void volume Vvc, which are the ISO 25178 international standard parameters. The effects of surface topographic parameters on friction were analyzed and the wear mechanism of the worn surface was presented. The wear characteristics of the samples were mainly characterized as strain fatigue, grinding, and scraping. The results provide a theoretical basis for the functional characterization of surface topography.
... • its length AR or AW measured parallel to direction of primary profile , • its two depths Hj i H j+1 measured perpendicularly to direction of primary profile, • its characteristic depth T, which is the lower depth of this two (� � ��� � � , ��� �. Fragments received this way are next joined according to specific rules among which following conditions are distinguished: envelope, length, magnification and equality [5,6]. ...
This article explores the methodology of assessing the applicability of roughness parameters from the motif group to the evaluation of one-way and periodic geometrical surface structures. The results of surface roughness measurements of aluminum samples turned with variable kinematic parameters were presented. Usability of using surface motifs in combination with selected parameters described in ISO standards for assessment of geometrical structures characteristic for longitudinal turning was shown.
... Alternative techniques to suppress the impact of globules and surface pores on waviness extraction are morphological filters [43], which are more relevant to the functional evaluation of surfaces, e.g. assembly, sealing, contact phenomenon [44][45][46]. For the purpose of surface filtration, circular disks are commonly used for profile data, while spherical balls are used for areal data. ...
Powder bed fusion (PBF) is a popular additive manufacturing (AM) process with wide applications in key industrial sectors, including aerospace, automotive, healthcare, defence. However, a deficiency of PBF is its low quality of surface finish. A number of PBF process variables and other factors (e.g. powders, recoater) can influence the surface quality. It is of significant importance to measure and characterise PBF surfaces for the benefits of process optimisation, product performance evaluation and also product design. A state-of-the-art review is given to summarise the current research work on the characterisation of AM surfaces, particularly PBF surfaces. It is recognised that AM processes are different from conventional manufacturing processes and their produced surface topographies are different as well. In this paper, the surface characterisation framework is updated to reflect the unique characteristics of PBF processes. The surface spatial wavelength components and other process signature features are described and their production mechanisms are elaborated. A bespoke surface characterisation procedure is developed based on the updated framework. The robust Gaussian regression filter and the morphological filters are proposed to be used for the separation of the waviness component due to their robustness. The watershed segmentation is enhanced to extract globules from the residual surface. Two AM components produced by electron beam melting (EBM) and selective laser melting (SLM), are measured and characterised by the proposed methodology. Both of the two filters are qualified for the extraction of melted tracks. The watershed segmentation can enable the extraction of globules. The standard surface texture parameters of different surface wavelength components are compared. A set of bespoke parameters are intentionally developed to offer a quantitative evaluation of the globules.
... The other characterization techniques named motif analysis proved to be successful in the characterization of functional properties of surfaces, especially in friction and contact problems [4,5]. Today, motif parameters are less used but the conclusions regarding the relationship between function and specification still remain crucial. ...
Anisotropy of surface texture can in many practical cases significantly affect the interaction between the surface and phenomena that influence or are influenced by the topography. Tribological contacts in sheet forming, wetting behavior or dental wear are good examples. This article introduces and exemplifies a method for quantification and visualization of anisotropy using the newly developed 3D multi-scale curvature tensor analysis. Examples of a milled steel surface, which exhibited an evident anisotropy, and a ruby contact probe surface, which was the example of isotropic surface, were measured by the confocal microscope. They were presented in the paper to support the proposed approach. In the method, the curvature tensor T is calculated using three proximate unit vectors normal to the surface. The multi-scale effect is achieved by changing the size of the sampling interval for the estimation of the normals. Normals are estimated from regular meshes by applying a covariance matrix method. Estimation of curvature tensor allows determination of two directions around which surface bends the most and the least (principal directions) and the bending radii (principal curvatures). The direction of the normal plane, where the curvature took its maximum, could be plotted for each analyzed region and scale. In addition, 2D and 3D distribution graphs could be provided to visualize anisotropic or isotropic characteristics. This helps to determine the dominant texture direction or directions for each scale. In contrast to commonly used surface isotropy/anisotropy determination techniques such as Fourier transform or autocorrelation, the presented method provides the analysis in 3D and for every region at each scale. Thus, different aspects of the studied surfaces could clearly be seen at different scales.
... The conventional height parameters also do not provide lateral information, e.g., characterization of the spacing or sequence of the heights. The motif analysis, that was developed in the 1980s in France, proved to be successful in the characterization of functional properties of surfaces, especially in friction and contact problems [4] [8]. Today, motif parameters are less used but the conclusions regarding the relationship between function and specification still remain crucial. ...
This paper demonstrates the use of multi-scale curvature analysis, an areal new surface characterization technique for better understanding topographies, for analyzing surfaces created by conventional machining and grinding. Curvature, like slope and area, changes with scale of observation, or calculation, on irregular surfaces, therefore it can be used for multi-scale geometric analysis. Curvatures on a surface should be indicative of topographically dependent behavior of a surface and curvatures are, in turn, influenced by the processing and use of the surface. Curvatures have not been well characterized previously. Curvature has been used for calculations in contact mechanics and for the evaluation of cutting edges. In the current work two parts were machined and then one of them was ground. The surface topographies were measured with a scanning laser confocal microscope. Plots of curvatures as a function of position and scale are presented, and the means and standard deviations of principal curvatures are plotted as a function of scale. Statistical analyses show the relations between curvature and these two manufacturing processes at multiple scales.
... Data created using areal surface measurement techniques may be used to characterise specific surface features using a toolbox of pattern recognition systems [7,[108][109][110]. Significant features can be extracted for analysis based on threshold values. ...
A comprehensive analysis of literature pertaining to surface texture metrology for metal additive manufacturing has been performed. This review paper structures the results of this analysis into sections that address specific areas of interest: industrial domain, additive manufacturing processes and materials; types of surface investigated; surface measurement technology and surface texture characterisation. Each section reports on how frequently specific techniques, processes or materials have been utilised and discusses how and why they are employed. Based on these results, possible optimisation of methods and reporting is suggested and the areas that may have significant potential for future research are highlighted.
... The motif analysis is performed on the unfiltered surface profile divided into a series of windows [11,12], as shown in Fig. 6. The three parameters-the mean depth of roughness motif R, the mean spacing of roughness motif AR and the largest motif height Rx were analysed. ...
This paper presents the comparison of precision hard cutting and abrasive processes in terms of the surface textures produced and their effects on enhancing functional properties. The main objective of such a comparison is to facilitate the decision whether to possibly replace grinding operations by hard turning with low feed rates. The experimental study performed includes hard turning operations with CBN cutting tools and grinding operations using CBN wheels. For this purpose, the stereometric features of turned and ground surfaces with the Sa roughness parameter of about 0.2 μm were compared. Apart from the set of 3D roughness parameters, the motif, fractal and frequency characteristics were analysed.
... Areal motif methods provide useful tools for the evaluation of surface geometry. Wolf pruning techniques are used as criterion and in combination with areal motif create stability for the motif method [12]. In the present study motif analysis is proposed to illustrate the surface structure of samples. ...
In the European Joint Research Project ‘Multidimensional Reflectometry for Industry’, a new gloss scale was developed with the aim to represent different levels of gloss, hue, roughness, and refractive indices. In this paper, the surfaces of six selected samples were thoroughly investigated using various measuring techniques in order to verify the outcome of the novel manufacturing processes in terms of distinct levels as well as types of surface roughness. The aim of the evaluation was to capture surface structures in different wavelength intervals utilizing a confocal microscope, a coherence scanning interferometer, and an atomic force microscope. Power spectral density functions were also calculated from the measurements and used to determine suitability of techniques for different roughness scales. The measurements show that the expected surface characteristics as well as different RMS roughness values are intimately connected to the perceived glossiness.
... Morphological method was initially introduced in image processing by Serra [34], and later on, it was used in other areas such as signal processing [35]. The basic concept of morphological signal processing is to modify the shape of a signal, by transforming it through its intersection with another object called the structuring elements (SEs). ...
Defective rolling bearing response is often characterized by the presence of periodic impulses. However, the in-situ sampled vibration signal is ordinarily mixed with ambient noises and easy to be interfered even submerged. The hybrid approach combining the second generation wavelet denoising with morphological filter is presented. The raw signal is purified using the second generation wavelet. The difference between the closing and opening operator is employed as the morphology filter to extract the periodicity impulsive features from the purified signal and the defect information is easily to be extracted from the corresponding frequency spectrum. The proposed approach is evaluated by simulations and vibration signals from defective bearings with inner race fault, outer race fault, rolling element fault and compound faults, respectively. Results show that the ambient noises can be fully restrained and the defect information of the above defective bearings is well extracted, which demonstrates that the approach is feasible and effective for the fault detection of rolling bearing. © 2015, The Korean Society of Mechanical Engineers and Springer-Verlag Berlin Heidelberg.
... The motif analysis is performed on the unfiltered surface profile divided into a series of windows [11,12], as shown in Fig. 6. The three parameters-the mean depth of roughness motif R, the mean spacing of roughness motif AR and the largest motif height Rx were analysed. ...
The problem of replacing costly and environmentally detrimental grinding operations by hard turning or milling processes needs further investigations related to the obtainable quality of machined parts. In author's opinion the problem should be extended to the surface texture generated in these contrary operations which is critical for service properties demanded by end-users. Taking these aspects into consideration, an extended study was performed to characterize surface topographies (3D surface roughness parameters) produced. In this case study, the turned and ground surfaces with the same Ra roughness parameter of about 0.3 μm were compared. Moreover, the frequency, furrows, fractal and motifs analyses have aided the final conclusions. The analysis done would assist technologists to select an optimum chain of machining operations.
This experimental research focuses on the nanostructure analysis of three materials; polyether ether ketone (PEEK), African land giant snail shell (ALGSS), and sea snail shell (SSS) powder, for the formation of hydroxyapatite (HA) coatings in bone implant applications. The study aimed to evaluate these materials’ surface characteristics, furrow depth, density, and other relevant parameters to assess their suitability as bone implant materials. The nanostructure analysis revealed distinct characteristics for each material. PEEK exhibited shallow furrows and a high density of furrows, making it a favourable substrate for hydroxyapatite coating formation. The ISO 25178 roughness analysis further characterised surface roughness and topography. African land giant snail shell powder, displayed a high material ratio, indicating a potential for hydroxyapatite conversion for biomedical application. The sea snail shell powder demonstrated intermediate furrow depth and density, warranting further investigation for optimisation as a precursor for hydroxyapatite coatings. The findings emphasise the significance of nanostructure properties in bone implant materials. The tailored nanostructure of materials such as PEEK, the synthesized powder can influence their biocompatibility, osseointegration, and long-term performance. The novelty of this research lies in the comprehensive analysis of the nanostructure properties of these materials, contributing to the understanding of their potential for bone implant applications. Overall, this experimental research is significant and provides valuable insights into the nanostructure characteristics of PEEK, African land giant snail shell powder, and sea snail shell powder and they all demonstrated the potential of forming hydroxyapatite coatings. These findings contribute to advancements in bone implantology, paving enhancing innovative and improved bone implant materials
Morphological profile filters effectively complement linear and robust Gaussian regression filters in roughness analysis. The advantages of morphological filters include simple elimination of edge effects and no need to exclude a form component from the profile in advance. The standard ISO 16610-41:2015, morphological profile filter is nonlinear and naturally robust. Therefore, it can be used to analyze multifunctional surfaces, for example, after honing. However, due to the nonlinearity of the filter, the obtained result strongly depends on the selected value of a nesting index and cannot always be compared with other filtering methods. The alternating symmetric filter according to ISO 16610-49:2015 provides additional tuning options. By sequentially combine openings and closings operations, it is possible to obtain different degrees of suppression of profile valleys and peaks. The most promising would be asymmetric morphological filter, which uses different nesting indexes for combinations of opening (O) and closing (C) operations. The present paper investigates the influence of the nesting index on the height roughness parameters. For this purpose, profile with preferential depressions after honing was analyzed. It was found that only two combinations of alternating morphological filter give different results, exhausting the variety of morphological combinations of opening and closing. In this case, the degree of suppression of valleys and peaks depends on the form of the primary profile. The filter m = C(O) proved to be the most effective. At that, a smaller nesting index should be taken at first, and then a larger one.
Five-axis machining plays an important role in manufacturing by dint of its high efficiency and accuracy. While two rotation axes benefit the flexibility of machining, it also brings limitations and challenges. In order to further balance machining precision and efficiency, an improved feedrate scheduling method is presented considering geometric error and kinematic constraints for the Non Uniform Rational B-Spline (NURBS) interpolation in five-axis machining. A simplification method is proposed to calculate the geometric error which describes the deviation between the ideal tool path and the real tool path induced by the non-linear movement. A linear relation between geometric error and feedrate is built to limit the feedrate. The constraints determined by single axis kinematic performance and tangential kinematic performance are also considered. Under these constraints, a constrained feedrate profile is determined. Aiming to get more constant feedrate in the difficult-to-machine areas, this work proposes a scheduling method which combines morphological filtering and S-shape acceleration/deceleration (acc/dec) mode. Simulations and experiments are performed to compare the proposed feedrate scheduling method with two previous feedrate scheduling method and the results prove that the proposed feedrate scheduling method is reliable and effective.
The flexibility in respect of design and manufacturing freedom that additive manufacturing (AM) offer are key driving factors for many industrial sectors. For example, designing and manufacturing unique internal conformal cooling/heating channels with enhanced functionalities for various applications like tools and heat exchangers. However, for the majority of the metal AM-processes in the as-build condition, AM is associated with high surface roughness, which has a measurable impact e.g on the heat transfer and flow properties. Hence, proper characterization of the fluid flow and heat transfer is vital to understand how the AM surfaces should be optimized for maximum output. The current study considers the effect of surface roughness and channels dimensions on the pressure drop and heat transfer. An experimental investigation was made of cooling channels produced by Powder-Bed-Fusion using Laser-Beam-Melting (PBF-LBM) additive manufacturing technique. Cooling channels with as-build surfaces was compared to post-processed cooling channels such as extrude honing and drilled channels, respectively. Results showed the lowest pressure drop for extrude honed channels compare to drilled and as-build channels, while heat transfer showed the same trend for as-build and extrude honed channels. The complexity of surface topography of as-build channels need to be described by parameters suitable for the detection of fluid interaction. Combination of different parameters remains to be investigated
Filtering for signal and data is an important technology to reduce and/or remove noise signal for further extraction of desired information. However, it is well known that significant distortions may occur in the boundary areas of the filtered data because there is no sufficient data to be processed. This drawback largely affects the accuracy of topographic measurements and characterizations of precision freeform surfaces, such as freeform optics. To address this issue, a Gaussian process machine learning-based method is presented for extrapolation of the measured surface to an extended measurement area with high accuracy prior to filtering the surface. With the extrapolated data, the edge distortion can be effectively reduced. The effectiveness of this method was evaluated using both simulated and experimental data. Successful implementation of the proposed method not only addresses the issue in surface filtering but also provides a promising solution for numerous applications involving filtering processes.
Promising methods of digital morphological filtration of the texture of a surface are considered. Results of a program implementation of morphological spatial filters for three-dimensional evaluation of surface texture are presented.
Morphological filters have been used successfully in image processing for the past few decades. Now they are beginning to be applied in the field of computational surface metrology. Morphological filters are closely related to envelope filters. A recently formed ISO group (ISO/TC 213/AG 9) is studying various filtering techniques,
including morphological filters, in order to assess their suitability for adoption as international guidelines and standards. As a part of this study discrete morphological filters for processing metrological data have been defined and their computability has been demonstrated. This paper defines morphological filters under consideration and
presents explicit MATLAB implementations of discrete versions of these filters. Two examples from metrology are illustrated.
The French automotive industry has been using for several years a special Motifs method to analyse the roughness through the evaluation of roughness motifs (ISO 12085). The main interest of this method is linked to the existence of a knowledge database, regularly updated since thirty years. This database contains values of R and W parameters for a large variety of functional components and engineering surfaces used in the automotive industry. The method has several drawbacks though, such as: it is difficult to implement, some exceptions are not covered by the standard, the method is not stable and sensitive to small local variations of the profile. A new method (called segmentation by watersheds), based on an image processing technique called segmentation by watersheds, could be used as a replacement. Initially developed for areal measurements, it can be adapted to 2D profiles and tuned to provide results very close to the ones provided by the ISO 12085 standard. This method is easier to implement, provides more stable results, and is less sensitive to exceptions. This paper describes how the segmentation method can be adapted to the evaluation of motifs, and provides a preliminary comparison between the two methods.
Surface texture and its measurement are becoming the most critical factors and important functionality indicators in the performanc of high precision and nanoscale devices and components. Surface metrology as a discipline is currently undergoing a huge paradig shift: from profile to areal characterization, from stochastic to structured surfaces, and from simple geometries to comple free-form geometries, all spanning the millimetre to sub-nanometre scales.
This paper builds a complete philosophical framework for surface metrology through a review of the paradigm shifts that hav occurred in the discipline of surface metrology, tracing the development of fundamental philosophies and techniques. The pape starts with a brief overview of the historical paradigm shifts and builds an up-to-date foundational philosophy, capable o rapid and effective development. The growth in interest in surface metrology stems mainly from the need to control the manufactur of armaments during the Second World War and the production of domestic goods and appliances since that time. The surface produced by manufacture seemed to offer the possibility of being useful for process control. Unfortunately, only a few tentativ investigations had been carried out to establish usable relationships between the processes, the machine tools and the availabl surface parameters (with their limitations). Even fewer investigations had been carried out to relate surface geometry t the performance of manufactured products. The result was that the metrology was unprepared and, consequently, the progres was sporadic.
This overall review is given in two parts. Part I focuses on the historical philosophy of surface metrology and Part II discusse the progress within the current paradigm shift.
Watershed segmentation and Wolf pruning, as defined in ISO 25178-2, allow the detection of significant features on surfaces and their characterization in terms of dimension, area, volume, curvature, shape or morphology. These new tools provide a robust way to specify functional surfaces.
Mathematical morphology is a theory of image transformations and image functionals which is based on set-theoretical, geometrical, and topological concepts. The methodology is particularly useful for the analysis of the geometrical structure in an image. The main goal of this paper is to give an impression of the underlying philosophy and the mathematical theories which are relevant to this field. The following topics are discussed: introduction to mathematical morphology; generalization to complete lattices; morphological filters and their construction by iteration; geometrical aspects of morphology (e.g., convexity, distance, geodesic operators, granulometries, metric dilations, distance transform, cost functions); and extension of binary operators to grey-scale images.
This is the second part of the paper ‘Paradigm shifts in surface metrology’. In part I, the three historical paradigm shift in surface metrology were brought together, and the subsequent evolution resulting from the shifts discussed. The historica philosophy highlighted the fact that the paradigm shifts must be robust and flexible, meaning that surface metrology mus allow for full control of surface manufacture and provide an understanding of the surface functional performance. Part I presents the current paradigm shift as a ‘stepping stone’, building on the above historical context. Aspects of surface geometr will also have to cater for surfaces derived from disruptive application, i.e. structured and freeform surfaces are identifie candidates. The current shift is presented in three aspects: from profile to areal characterization; from stochastic to structure surfaces; and from simple geometries to complex freeform geometries, all spanning the millimetre to sub-nanometre scales.
In this paradigm shift, the scale of surface texture is beginning to approach some of the geometrical features in micro/nan electro-mechanical systems devices and is becoming one of the most important functionality indicators. Part II will contextualiz the current shifts in the discipline of surface metrology, and cement surface metrology in place in the ultra precision an nanotechnology age.
This paper presents a novel method for the analysis of solid surfaces in contact with a conformable component. These applications are common in many engine and hydraulic applications, wherein conformable seals, gaskets, bushings, etc. are employed to prevent unwanted flow across an interface or provide a uniform load distribution. The proposed analysis method employs a combination of meanline (m-system) filtering and envelope (e-system) or morphological filtering. Through this analysis, a simulation of contact area and the associated voids or gaps can be assessed.
The real geometry of a workpiece has including their micro-and macro-geometrical deviations an effect on the one hand to the functional behaviour and on the other hand to the real geometry marks of the whole manufacturing process. The metrology has, because of the mutual relations between function and manufacturing, the important task to purify the connections between the real geometry and the function. Parameters and functions have to be defined and standardized for the complete description of the surface roughness and waviness to be suitable for the functional, productional and meteorological requirements. Surface roughness and waviness measurements in industry are internationally widespread performed by stylus instruments. To separate roughness from waviness, the mean line system uses electronic filtering. The MOTIF-method (ISO 12085) offers an alternative evaluation to separate roughness and waviness by means of unfiltered profiles. The MOTIF-method is a graphical evaluation with the complete description of roughness and waviness with merely 7 parameters and the evaluation based on the upper envelope line. The MOTIF-method is a system for the evaluation of the primary profile and based on the envelope system and is suitable as an alternative to the mean line system. The MOTIF-method determines the upper points of the surface profile, which have an importance for the functional behaviour. Roughness and waviness can be evaluate directly based on the diagram of the unfiltered profile. Specially the evaluation of short profiles is advantageous, as the MOTIF-method requires no pre-and post-travel. The parameter of the MOTIF-method reflects the geometrical dimension of the profile irregularities. The typical surface profile is possible to be reconstructed with the additional informations of the variances. The separation of roughness from waviness happens absolute sharp with an automatically adjustment to the width of the characteristic irregularities of the profile. The MOTIF-method finds out within these limits the horizontal and vertical properties of the essential profile irregularities without elimination of important profile points. It is very well suited for technical inquiries on unknown surfaces and processes, functions related to the envelope of the surfaces and profiles with very close wavelengths for roughness and waviness.
The E-system of roughness measurement can be used either for a two dimensional or a three-dimensional assessment of surface roughness. The procedure for computing che two- and three-dimensional envelopes from digitized profiles is briefly explained. This mechod will be useful for verifying the results obcained by practical inscruments. The filtering chracceristic of che E-system, when used for cwo- and three-dimensional roughness measurement, is analysed with reference to theorecical profiles. Various skid configurations are studies using a doubly curved skid simulated by a computer. (A)
Morphological filters, regarded as the complement of mean-line based filters, are useful in the analysis of surface texture and the prediction of functional performance. The paper first recalls two existing algorithms, the naive algorithm and the motif combination algorithm, originally developed for the traditional envelope filter. With minor extension, they could be used to compute morphological filters. A recent novel approach based on the relationship between the alpha shape and morphological closing and opening operations is presented as well. Afterwards two novel algorithms are developed. By correlating the convex hull and morphological operations, the Graham scan algorithm, original developed for the convex hull is modified to compute the morphological envelopes. The alpha shape method depending on the Delaunay triangulation is costly and redundant for the computation for the alpha shape for a given radius. A recursive algorithm is proposed to solve this problem. A series of observations are presented for searching the contact points. Based on the proposed observations, the algorithm partitions the profile data into small segments and searches the contact points in a recursive manner. The paper proceeds to compare the five distinct algorithms in five aspects: algorithm verification, algorithm analysis, performance evaluation, end effects correction, and areal extension. By looking into these aspects, the merits and shortcomings of these algorithms are evaluated and compared.
This paper gives an overview of the progress which has been made in surface metrology over the past ten years. It updates the surface classification system, and discusses the practical and theoretical reasons for the technological shifts which have occurred. This includes the use of surfaces with predetermined features as an alternative to traditional machined surfaces, and the move from simple to freeform shapes. The paper discusses technological shifts in association, filtration, numeric parametric techniques, fractals associated with function and standardisation. Many examples are given in order to contextualise the significance of these technological changes. This paper should help to predict the direction of future developments in surface metrology, and therefore emphasise its importance in functional applications in advanced manufacture.
To extract patterns from observable measurements we need to be able to define and identify stable features in observable measurements that persist in the presence of small artificial features such as noise, measurement errors, etc. The representational theory of measurement is used to define the stability of a measurement procedure. A technique, 'motif analysis', is defined to identify and remove 'insignificant' features while leaving 'significant' features. This technique is formalized and three properties identified that ensure stability. The connection of motif analysis with morphological closing filters is established and used to prove the stability of motif analysis. Finally, a practical metrology example is given of motif analysis in surface texture. Here motif analysis is used to segment a surface into its significant features.
Common functional requirements of work pieces are sliding, adhering, sealing and assembling. These requirements are asking for specific properties of surfaces. Surfaces of work pieces are described by geometrical properties such as dimension, orientation, form, waviness and roughness. Functional requirements need to be expressed by specifying these geometrical features. With the existing definitions for orientation, form, waviness and roughness a holistic description of functional surface properties is not possible.Based on the function a holistic view of the surface properties including dimension, orientation, form, waviness and roughness is necessary. The existing classification of the surface based on wavelength is in combination with the mean line filtering an incomplete definition. The dimension and orientation of the work piece geometry is not even considered. With the revitalization of the envelope system there is a new approach to establish a correlation between the functional requirements and geometrical properties of the work piece surface.This new approach consists of the implementation of morphological filter operations to associate dimension, orientation, form, waviness and roughness based on a common reference system. This common reference system is equal to the envelope of the work piece. Proposals to describe the functional requirements with new parameters are presented.
The height and spacing characteristics of the surface profile influence the functional behaviour of the manufactured part. A new method known as motif combination has been recommended in French standards to obtain the height and spacing characteristics of the surface profiles. An attempt has been made in this paper to compare motif combination techniques with the mean line and envelope systems, taking practical profiles.
A new method of determining the roughness parameter R and the waviness parameter W is presented: the method is based on work carried out in the French motor industry in 1980–1981 on computer simulation to determine R and W. A method was derived on the basis of such simple and general principles that it is expected to attract interest in areas other than its intended area of application.
The E-system of roughness measurement can be used either for a two-dimensional or a three-dimensional assessment of surface roughness. The procedure for computing the two- and three-dimensional envelopes from digitized profiles is briefly explained. This method will be useful for verifying the results obtained by practical instruments. The filtering characteristic of the E-system, when used for two- and three-dimensional roughness measurement, is analysed with reference to theoretical profiles. Various skid configurations are studied using a doubly curved skid simulated by a computer.
This article presents a 3D extension of the motif method (ISO 12085), where 3D-motifs are defined as the catchment basins of a surface, separated by watershed lines. The interest of this approach is that its restriction to profiles leads to the same motif notion as in the standardised method. Catchment basins are determined using an algorithm simulating global surface immersion, They are progressively combined to perform a multiscale analysis of surface features and extract all the significant motif sets, from roughness to waviness. The originality of the proposed method lies in the indirect motif combination process used, which never requires the direct combination of adjacent motifs. This guarantees the stability and uniqueness of the solution. After a theoretical overview of the method, results obtained from various engineering surfaces are presented and new statistical parameters for surface characterisation, calculated from 3D-motifs are proposed.
The concept of Motif Combination was introduced in the French Automotive industry's R&W standard. There has however been no formal mathematical theory for the technique of motif combination. This paper sets out to develop this theory. The main result of the paper is a set of four properties that the motif combination rules must satisfy in order to have certain desirable metrological properties.Motif methods may well provide useful techniques which complement rather than replace the traditional approach based on a mean line. It was found that many functional problems could be simulated very efficiently using motif methods. Examples of functional simulation via motif combination are illustrated in the paper.
This report explains the “Motifs” method, proposed by France at the last meeting of the ISO/TC 57 committee, and was accepted by the unanimity of delegates. It shows how the parameters related to the “motifs” are complementary to the present ISO parameters, and gives functional examples of the interest of measuring waviness of the envelope line for some technical problems met in the French industry. It is important to notice that this paper is not a resurrection of old quarrels between mean line and envelope line “systems”, but is to be a complementary approach to solve specific technical problems.
The surface summits and their waviness envelope constitute the boundary surface of contact area during the tribological life of solids. The form, scale and orientation of the three-dimensional motifs play an important role on flatness behaviour of engineered surfaces, contact mechanics, adherence, friction, lubrication and leakage problems. The basic idea of this work considers that the three-dimensional motifs of the surface are a key elements of surface topography in regard to different field of tribology. The 2D motif is defined as the part of profile which associates tow peaks separated a deep valley (pit). The extension of the 2D motif definition to the 3D morphology needs the simultaneous assessment of waviness and roughness. The approach developed in this work is based on a geomorphologic definition of 3D motif. The approach is improved by a new algorithm of waviness envelope construction and a morphologic filter using the waviness envelope as a low-frequency surface of filtering.
The real geometry of a workpiece has including their micro- and macro-geometrical deviations an effect on the one hand to the functional behaviour and on the other hand to the real geometry marks of the whole manufacturing process. The metrology has, because of the mutual relations between function and manufacturing, the important task to purify the connections between the real geometry and the function. Parameters and functions have to be defined and standardized for the complete description of the surface roughness and waviness to be suitable for the functional, productional and meteorological requirements. Surface roughness and waviness measurements in industry are internationally widespread performed by stylus instruments. To separate roughness from waviness, the mean line system uses electronic filtering. The MOTIF-method (ISO 12085) offers an alternative evaluation to separate roughness and waviness by means of unfiltered profiles. The MOTIF-method is a graphical evaluation with the complete description of roughness and waviness with merely 7 parameters and the evaluation based on the upper envelope line. The MOTIF-method is a system for the evaluation of the primary profile and based on the envelope system and is suitable as an alternative to the mean line system. The MOTIF-method determines the upper points of the surface profile, which have an importance for the functional behaviour. Roughness and waviness can be evaluate directly based on the diagram of the unfiltered profile. Specially the evaluation of short profiles is advantageous, as the MOTIF-method requires no pre- and post-travel. The parameter of the MOTIF-method reflects the geometrical dimension of the profile irregularities. The typical surface profile is possible to be reconstructed with the additional informations of the variances. The separation of roughness from waviness happens absolute sharp with an automatically adjustment to the width of the characteristic irregularities of the profile. The MOTIF-method finds out within these limits the horizontal and vertical properties of the essential profile irregularities without elimination of important profile points. It is very well suited for technical inquiries on unknown surfaces and processes, functions related to the envelope of the surfaces and profiles with very close wavelengths for roughness and waviness.
The basic problem of measuring real surfaces with a tactile probe is the distortion of the measured profile due to the tip geometry in comparison with the real profile. The bigger the ratio of the characteristic dimension of the tip and the shortest describing wavelength of the surface, the larger the relative distortion will be. That must especially be taken into account in the case of the measurement of nano structures. To reverse this distortion a morphological operation for the reconstruction of the mechanical surface is investigated. The results demonstrate the efficiency and the limits of the reconstruction to obtain the mechanical surface, which also depends on the morphological extraction theorem.
A surface topography decomposition methodology is presented. It decomposes a surface into three elements: reference surface (waviness and form); superficial roughness (related to friction and wear); and valleys (related to lubricant circulation and reservoirs). It is applied to cylinder liners from an internal combustion V6 engine from in order to remove form and waviness components. The study of the resulting superficial roughness component has allowed a precise wear characterization.
- Von Weingraber
H. Von Weingraber, Ü ber die Eignung des Hüllprofils als Bezugslinie
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für die Messung der Rauheit, Ann. CIRP 5 (1956) 116-128.
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Morphological Profile Filters: Basic Concepts
Part 40: Morphological Profile Filters: Basic Concepts, 2010.
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The MOTIFS-method -an interesting complement to 547
- J Boulanger
J. Boulanger, The MOTIFS-method -an interesting complement to
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