Standard Roughness Parameters Research Articles

Roughness variations in cylinder liners induced by honing tools’ wear

The manufacturing and finishing (honing) of cylinder liners for the automotive industry is a constant challenge in order to reduce friction losses and oil consumption. A better knowledge of surfaces generated during plateau honing is then required for optimization of the process. Despite a well-known and controlled honing process, variations in surface roughness appear due to honing tool wear and need to be mapped and analyzed. The following paper proposes to map the variations in roughness by using confocal 3D measuring equipment able to inspect any area of a cylinder liner. Six motor blocks, each with five cylinder liners, were evaluated with 20 topography measurements per liner (giving six hundred 3D measurements in total). In addition to standard 3D roughness parameters, tailor made parameters extracting honing texture information are computed. The results show that only a few parameters (Spk, Ssc and Sk) do correlate with the honing tool wear specific to each cylinder. Tailor made parameters indicate similar results. Indeed, as the honing tool wears down, the cylinder liner surface gets rougher plateau or peaks and sharper asperities indicating that ploughing occurs instead of cutting. In future, experimental models could be built in order to perform production and functional optimizations.

Characterization of surface textures generated on hardened steel parts in high-precision machining operations

This paper presents the comparison of surface textures produced by high-precision cutting and abrasive processes on hardened steel parts. Investigations include surfaces generated by hard turning, belt grinding, and superfinishing (external honing) operations. As a result, several surfaces generated with different process kinematics and the Sa roughness parameter of about 0.05 μm were compared. Apart from the standard 2D and 3D roughness parameters, the fractal, motif, and frequency parameters were considered.

High-precision Finishing Hard Steel Surfaces Using Cutting, Abrasive and Burnishing Operations

This paper presents the technological and functional capabilities of surface textures produced by high-precision cutting, abrasive and ball burnishing operations on hardened steel parts of about 60 HRC hardness. Special focus was placed on surface textures generated by hard turning, belt grinding and ball burnishing operations which are characterized by the Sz roughness parameter of about 1.3μm and distinctly different values of the Sa parameter. Apart from the standard 2D and 3D roughness parameters, the fractal and motif parameters were analyzed.

10607 精密切削加工面の摩擦特性を評価するGPSパラメータの開発

In engineering fields, surface roughness parameters are widely used for mechanical designs. However, actual surfaces have many factors which we cannot express by using a single standard surface roughness parameter. We think that there is needed to develop a geometry parameter which is applied to all surface conditions and to characterize tribological properties based on an ideal surface whose roughness parameters are completely controlled. In this study, effects of grooves on the surface roughness parameters and the tribological properties were investigated. The grooves have various pitches, processed by ultra-precision cutting. A correlation between the change of the grooves on boundary lubrication and the standard surface roughness parameters are discussed.

Quantitative assessment of the interfacial roughness in multi-layered materials using image analysis: Application to oxidation in ceramic-based materials

A method is developed to characterize interfacial roughness of layered materials. A series of contiguous images is acquired with a Scanning Electron Microscope on polished cross-sections. Using image analysis algorithms based on mathematical morphology operations, interface profiles are extracted and mathematically processed to calculate standard surface roughness parameters. In addition, morphological criteria describing the interface tortuosity are determined, such as the “normalized rumpling index” (based on the profile developed length) and the “barbule density” that quantifies the protrusions of the layer (using the skeletonization function). The validity and accuracy of the method is evaluated by comparison with measurements performed by the conventional surface metrology techniques. This method is used to study internal oxidation of two ceramic-based materials (Si3N4–TiN composite/thermal barrier coatings) upon thermal aging. In both cases, a link is established between the roughening of the oxide layer interface and a decrease in the mechanical strength of the multi-layered material.

Liner surface improvements for low friction piston ring packs

The development of engine components in the automotive industry is governed by several constraints such as environmental legislation and customer expectations. About a half of the frictional losses in an internal combustion engine come from the interactions between the piston assembly and cylinder liner surface. The tribological considerations in the contact between the piston ring and cylinder liner have attracted much attention over the past few decades. Many non-conventional cylinder liner finishes have been, and are being, developed with the aim to reduce friction losses and oil consumption, but the effects of the surface finish on piston ring pack performance is not well understood. One way of reducing friction in the cylinder system is to reduce the tangential load from the piston ring pack, focusing on the oil control ring. However, the side-effect of this is a disappointingly increased oil consumption. In this study a number of different cylinder liner surface specifications were developed and implemented in test engines with the aim of maintaining the level for oil consumption when decreasing the tangential load for the piston ring pack. To improve our understanding of the result, the same surfaces were evaluated in elastic and elasto-plastic rough contact and hydrodynamic flow simulation models. It is shown that oil consumption is strongly related to surface texture on the cylinder liners and at lower speeds (900–1200 rpm), a ‘rougher surface’ with a high core (e.g. Sk) and valley roughness (e.g. Svk) results in higher oil consumption. At the medium speed range (1200–3600 rpm), oil consumption continues to dominate for the ‘rough’ surfaces but with a visible influence of a lower oil consumption for a decreased roughness within the ‘rough’ surface group. ‘Smooth’ surfaces with a ‘smooth’ core (Sk), irrespective of the valley component (Svk), show similar oil consumption. For engine speeds above 3600 rpms, an increase in plateau roughness results in higher oil consumption. Throughout the study, standard roughness parameters were computed to compare with the results from engine testing and simulation. Future work will be directed to continuous optimization between oil consumption and friction. Improving the understanding of the functional cylinder system surfaces' ability to form oil films in the cylinder system opens up opportunities, not only in reducing the tangential load of piston ring packs but also in optimizing oil viscosity in order to reduce friction.

Surface Roughness Evaluation of Treated Woven Fabric by Using a Textile Surface Tester

Consumers use their sense of touch instinctively to evaluate a garment's quality and faculty for specific use. The roughness of textiles is an important parameter for customers' choice of garments. This work focused on surface roughness of woven fabrics. A Textile Surface Tester (TST) was used in this study. For surface height variation (SHV) characterization, the standard roughness parameters described in the ISO 4287 was frequently used. During this analysis, we examined the effect of different parameters of manufacturing and finishing samples on the variation in surface roughness. It was found that the fabric type had an important effect on surface roughness as well as the weft count of woven samples, while chemicals treatments, as coating with different commercial products via ink-jet printing and drying processes, did not affect this parameter.

Wettability of hydraulically profiled low-carbon steel substrates

Surfaces obtained after water jet treatment were evaluated in terms of roughness and static equilibrium contact angles. Relationships between standard roughness parameters and measured contact angles could not be established. A model introduced by Kubiak et al. [Wear 271 (2011) 523–528] was utilised, which provided qualitatively correct trends. Exceptions were situations with very short exposure times. In terms of quantitative evaluation, the model generally overestimated the measured contact angles on isotropic surfaces. It is suggested that the formation of very narrow cracks in the surface can obliterate geometric profile effects and deteriorate wettability.

Energy efficiency optimization of engine by frictional reduction of functional surfaces of cylinder ring–pack system

Friction reduction, lower oil consumption, and limitation of greenhouse gases emissions are the chief objectives of the automotive industry in order to improve the environmental efficiency of vehicle engines.In this paper, a strategy for ring–pack friction reduction through cylinder liner finish optimization based on coupling instrumented honing experiments and numerical prediction of elastohydrodynamic friction is proposed.The results show that honed surfaces produced by fine abrasion by honing stones yield the optimal elastohydrodynamic friction. They also demonstrate the limitations of ISO 13565 standard roughness parameters in giving a complete description of the functional performances of cylinder surface finishes.

Correlation between standard roughness parameters skewness and kurtosis and tribological behaviour of contact surfaces

The aim of the present research was to investigate the correlation between surface roughness parameters and friction. For this purpose 100Cr6 steel plate samples were prepared using different grades and combinations of grinding and polishing in terms of similar Sa but different Ssk and Sku values. Dry and lubricated pin-on-disc tests, using different contact conditions, were carried out, using Al2O3 ball as counter-body. Test results show that surfaces with higher Sku and negative Ssk values tend to reduce friction.

Fabric Texture Analysis Using Computer Vision Techniques

This paper presents inexpensive computer vision techniques allowing to measure the texture characteristics of woven fabric, such as weave repeat and yarn counts, and the surface roughness. First, we discuss the automatic recognition of weave pattern and the accurate measurement of yarn counts by analyzing fabric sample images. We propose a surface roughness indicator FD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FFT</sub> , which is the 3-D surface fractal dimension measurement calculated from the 2-D fast Fourier transform of high-resolution 3-D surface scan. The proposed weave pattern recognition method was validated by using computer-simulated woven samples and real woven fabric images. All weave patterns of the tested fabric samples were successfully recognized, and computed yarn counts were consistent with the manual counts. The rotation invariance and scale invariance of FD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FFT</sub> were validated with fractal Brownian images. Moreover, to evaluate the correctness of FD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FFT</sub> , we provide a method of calculating standard roughness parameters from the 3-D fabric surface. According to the test results, we demonstrated that FD <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">FFT</sub> is a fast and reliable parameter for fabric roughness measurement based on 3-D surface data.

Surface Texture’s Role in Assessing Surface Integrity of Machined Parts

Surface texture, as one of the typical surface integrity characteristics, plays a vital part in efficiently and systematically evaluating the surface integrity and relevant mechanical properties of machined parts. Commonly used 2D surface roughness parameters are formularized and discussed in this paper. And 3D characterization technique is also illustrated through measuring and describing a machined surface with an optical profiling system. The relationship between surface texture and the fatigue property of final machined parts are discussed by employing the quantity of effective stress concentration factor which could be expressed by the standard surface roughness parameters and measured averaged root radius of surface texture’s valleys. This research emphasizes the indispensable role of the surface texture in evaluating surface integrity and corresponding functional performance of machined parts.

Methodologies for assessing local surface texture features that are relevant to cell attachment

In this paper, we describe techniques for extracting features from surface topography data, gathered by a 3D-microscopy system, on a length scale that is relevant for cell attachment. The feature parameters considered include standard surface roughness parameters applied to the complete surface as well as new feature parameters designed to quantify local variations in surface topography potentially influencing cell behaviour. Methodologies have been developed both to determine the degree of homogeneity or isotropy of a surface and to compare the topographies of different samples. The approaches followed include wavelet decomposition and linear and nonlinear filtering techniques. The analysis has been used to investigate the correlation between osteoblast cell attachment and structural features of titanium-coated surfaces representative of orthopaedic implants. The results confirm that there is a discernible correlation between cell orientation and the underlying surface lay.

Improvement in skin wrinkles from the use of photostable retinyl retinoate: a randomized controlled trial

Photoaged skin can be treated with retinoids, which are natural and synthetic vitamin A derivatives. However, these are photounstable and can cause skin irritation, which is a major limitation in their use in general cosmetics. Retinyl retinoate, which is an ester of all-trans retinoic acid (RA) and all-trans retinol, has reduced toxicity due to blocking of the carboxyl end group of RA and higher skin regeneration activity than retinol. To assess the efficacy of a photostable retinyl retinoate in treating women over 30 years old with periorbital wrinkles. We conducted two clinical studies with a total of 46 Korean women with periorbital wrinkles, who were not pregnant, nursing or undergoing any concurrent therapy. In the first clinical study, the efficacy of retinyl retinoate was compared with placebo. Twenty-four patients completed a 12-week trial of 0.06% retinyl retinoate applied twice daily to one side of the face and a placebo applied to the other side. In the second clinical study, the efficacy of retinyl retinoate was compared with retinol. Twenty-two patients completed an 8-week trial of 0.06% retinyl retinoate applied twice daily to one side of the face and 0.075% retinol applied to the other side. Efficacy was based on a global photodamage score, photographs, and image analysis using replicas and visiometer analysis (Skin-Visiometer SV 600; Courage & Khazaka, Cologne, Germany) every 4 weeks. The standard wrinkle and roughness parameters used in assessing skin by visiometer were calculated and statistically analysed. The retinyl retinoate-treated wrinkles improved compared with wrinkles treated with placebo or retinol, as assessed by both the investigators and the subjects. Also, skin replica analysis indicated significant improvements in retinyl retinoate-treated skin in both studies, especially in average roughness. Retinyl retinoate applied twice daily was significantly more effective than a placebo or retinol in treating periorbital wrinkles. Importantly, no severe side-effects were observed.

About the validity of the plastic wave model for an actual roughness of axisymmetric tooling in bulk forming

The plastic wave friction model proposed for bulk forming simulation is a synthesis of the Coulomb-Amonton and Tresca-constant friction stress laws. It is based on a theoretical triangular shaped roughness whence machining of axisymmetric tooling surface with inserts induces a circular arc roughness profile. For two different surface punches with the same standard roughness parameters, the numerical modelling of a particular upsetting of a cylindrical billet of perfect plastic material shows how a circular arc roughness profile induces more friction than a triangular one with the analysis of the plastic flow inside the roughness asperities in the frame work of a mesoscopic approach.

Surface analysis on rolling bearings after exposure to defined electric stress

This article gives an overview about classical and frequency converter-induced spurious bearing currents in induction machines and discusses typical damage patterns caused by the current passage. To investigate on the electric damage mechanisms, test bearings are operated in a test rig and exposed to specific (classical low-frequency, and high-frequency) bearing currents. The induced damages to the surfaces are analysed visually and with the help of an atomic force microscope, and compared for the different electric regimes applied. Further, the electrically damaged bearing surfaces are characterized by standard roughness parameters. The surface structure observable on certain test bearings shows good correlation to the structure found with a bearing that had failed in the field under similar electric conditions. One of the investigated electric regimes applying high-frequency currents proved capable of generating fluting patterns - as found in real applications - on the test rig. The experiments also indicate that high-frequency bearing currents, although in total dissipating less energy, are more dangerous to a bearing than continuous current flow. The presented method gives a good starting point for further investigation on electric current damage in bearings, especially regarding high-frequency bearing currents, and on bearing/grease lifetime under specific electric regimes.

Implementation of Whitehouse's method for calculating properties of self-affine fractal profiles

Many software packages for roughness analysis offer the possibility of calculating the fractal dimension D of surface profiles by techniques, which assume them to be self-similar and therefore uniquely defined by D. However, fractal profiles are not self-similar but self-affine, so that two profiles of quite different roughnesses may share the same fractal dimension. To distinguish between them requires the calculation of an additional scaling factor, the so-called topothesy Λ. Traditionally, D and Λ are derived laboriously from the slope and intercept of the profile's structure function. A quicker and more convenient derivation from standard roughness parameters has been suggested by Whitehouse. Based on this derivation, it is here shown that D and Λ depend on two dimensionless numbers: the ratio of the mean peak spacing to the rms roughness and the ratio of the mean local peak spacing to the sampling interval. Using this approach, values of D and Λ are calculated from the measurements on surface profiles produced by polishing, plateau honing, and various single-point machining processes. Different processes are shown to occupy different regions in D–Λ space, and polished surfaces show a relationship between D and Λ, which is independent of the surface material.

An evaluation of surface roughness parameters measurement using vision-based data

This paper presents a methodology for using machine vision data to acquire reliable surface roughness parameter measurement. Stylus-based measurements were acquired and compared to vision-based measurements using standard and non-standard roughness parameters. Two light reflection models namely Intensity-Topography Compatible (ITC) model and Light-Diffuse model were adopted and applied to interpret acquired vision data and to enable suitable computation of roughness parameters. Results showed that the ITC model gives more superior results compared to the Light-Diffuse model with remarkable close values to those acquired by the traditional stylus-based data of all roughness parameters but the Skewness parameter ( R sk). In the case of the Skewness parameter ( R sk), however, it was shown to provide highly different values from those acquired by stylus technique. The overall acquired results indicate that vision systems are a valid source of data to obtain both amplitude and spacing roughness parameters with confidence using the proposed methodology. It is expected that these results would encourage further developments in the area to achieve commercial 3D vision-based roughness measurement systems for industrial use.

Fabrication of material-independent morphology gradients for high-throughput applications

Gradient surfaces allow rapid, high-throughput investigations and systematic studies in many disparate fields, including biology, tribology and adhesion. We describe a novel method for the fabrication of material-independent morphology gradients, involving a two-step process of particle erosion followed by a chemical polishing procedure that preferentially removes features with a small radius of curvature as a function of time. Gradients are fabricated on aluminium surfaces, but they may be readily transferred to other materials via a replication technique, which allows for the production of identical roughness gradient samples with any chosen surface chemistry. The gradients have been characterized by means of scanning electron microscopy and optical profilometry. Standard roughness parameters (Ra, Rq, Rz, Sm and Sk) were calculated from optical profilometry data. The roughness has also been assessed over different wavelength windows by means of a fast Fourier transformation approach.

Fabric Surface Roughness Evaluation Using Wavelet-Fractal Method

A wavelet-fractal method to calculate the fractal dimension is proposed to objectively evaluate the surface roughness of fabric wrinkle, smoothness appearance and seam pucker. The proposed method was validated using the fractal surfaces produced from the mathematical functions and compared with the box and cube counting methods. The more accurate three-dimensional mesh grid data points of wrinkle replicas, smoothness appearance replicas and seam pucker samples were obtained using a three-dimensional, noncontact scanning system. As a supplementary reference the standard roughness parameters, which differentiate the degree of fabric surface roughness, were also investigated. The results show that the fractal dimension measured by the wavelet-fractal method as well as the surface average mean curvature show the power to clearly discern the grades of wrinkle, smoothness appearance as well as seam pucker, and thus can evaluate the fabric surface roughness objectively and quantitatively