Roughness Parameters Research Articles

Spatial frequency decomposition with bandpass filters for multiscale analyses and functional correlations

To address the essential problem in surface metrology of establishing functional correlations spatial, frequencies in topographic measurements are progressively decomposed into a large number of narrow bands. Bandpass filters and commercially available software are used. These bands can be analyzed with conventional surface texture parameters, like average roughness, Sa, or other parameters, for detailed, multiscale topographic characterizations. Earlier kinds of multiscale characterization, like relative area, required specialized software performing multiple triangular tiling exercises. Multiscale regression analyses can test strengths of functional correlations over a range of scales. Here, friction coefficients are regressed against standard surface texture parameters over the range of scales available in a measurement. Correlation strengths trend with the scales of the bandpass filters. Using bandpass frequency, i.e., wavelength or scale, decompositions, the R2 at 25 μm, exceeds 0.9 for Sa compared with an R2 of only 0.2 using the broader band of conventional roughness filtering. These improved, scale-specific functional correlations can facilitate scientific understandings and specifications of topographies in product and process design and in designs of quality assurance systems.

Mechanical properties of 3D-printed resin denture teeth: An in vitro study.

The purpose of this study was to compare the wear, fracture strength, and mode of failure of various brands of 3D-printed resin denture teeth with prefabricated acrylic resin. Additionally, the study aimed to analyze the different modes of failure exhibited by these teeth. The study utilized 90 3D-printed and 30 prefabricated, 3D-printed resin teeth from three brands: L = Optiprint Lumina, A = ASIGA DentaTooth, P = Power resins, along with prefabricated acrylic teeth from M = Major Super Lux. Each of the 30 samples per main group was divided into two subgroups: The first subgroup samples (M1, A1, L1, P1) were subjected to thermal cycling and mechanical loading; M2, A2, L2, and P2 were not aged and tested directly. A scan of a prefabricated acrylic tooth was taken using an intraoral scanner, and then the STL file was printed using an Asiga 3Dprinter. The specimens underwent aging to simulate 5 years of clinical use with 10,000 thermal cycles and 1,200,000 dynamic load cycles on a chewing simulator. Surface roughness parameters (Rz, Ra, Rq) were measured using a 3D Optical Profilometer, fracture resistance was assessed using a universal testing machine, and SEM analysis was performed to observe failure modes. Statistical analysis using T-test, one-way analysis, and two-way analysis processed by the Statistical Package for Social Sciences (SPSS) software version 23.0 (SPSS: Inc., Chicago, IL, USA) was done with a level of significance set at <0.05. The results showed that the difference in surface roughness parameters (Rz, Ra, Rq) before and after aging for Group M, Group A, Group L, and Group P was statistically significant (p < 0.05). Two-way ANOVA for wear resistance between aging and groups on dependent variable Rz (p = 0.002), Ra (p = 0.001), Rq (p = 0.001) were significant. Multiple comparisons for surface roughness parameters showed Group A and Group L were lower than Group P and Group M (p < 0.05). For fracture strength, One-way ANOVA showed a significant difference between groups for fracture strength either without or after the aging procedure (p < 0.05). Multiple comparisons for fracture strength without aging showed no significant difference between Group M, Group A, and Group L (p > 0.05). After the aging procedure fracture strength for Group M was higher than Group A, Group L, and Group P (p < 0.05). 3D-printed resin teeth showed a greater and comparable wear resistance to prefabricated acrylic teeth. Fracture strength was comparable between prefabricated acrylic teeth and 3D-printed resin (Asiga and Lumina) before aging, but after aging 3D-printed resin teeth showed less fracture strength.

A numerical procedure for calculating roughness parameters for the Greenwood-Tripp model of asperity contact based on 3D measurements

This study introduces the proposed deterministic methodology for calculating the roughness parameters involved in the Greenwood-Tripp equation for asperity contact pressure. A robust methodology that takes into consideration the maximum possible peak morphology and establishes more stringent calculation conditions is proposed. The stability of the proposed method is examined on various samples taken from different engine components using an optical interferometer. The roughness parameters obtained from different methodologies and using different optical interferometer resolutions are compared, and then, these parameters are introduced into simulation model that employs the Greenwood-Tripp equation. The results demonstrate the sensitivity of the simulation model to the roughness parameters used.

Optimization and evaluation of thermo-hydraulic performance of solar air heaters equipped with different roughness geometries

Solar air heaters have poor thermal efficiency. Applying artificial roughness elements is a common approach to enhance thermal performance of a solar air heater. In this study, fluid flow and heat transfer characteristics of solar air heaters equipped with six different roughness geometries, including inline cubical elements, staggered cubical elements, rectangular baffles, square ribs, V-shaped baffles, and V-shaped ribs, were assessed. First, parameters of each roughness geometry were optimized and then thermo-hydraulic performance of solar air heaters having optimum roughness geometries was compared. For each roughness geometry, two design parameters were selected and 25 numerical experiments were designed based on the full factorial design of experiment approach. The thermo-hydraulic performance parameter (THPP) was set out as the objective function and its relationship with roughness parameters was defined using the non-parametric regression response surface method. Finally, the optimum values of roughness parameters were determined using the nonlinear programming by quadratic Lagrangian (NPQL) technique. Comparing the performance of solar air heaters having optimum roughness geometries showed that rectangular baffles led to the largest and inline cubical elements brought about the smallest THPP at almost all Reynolds numbers. The maximum THPP of rectangular baffles was 2.28 at the Reynolds number of 25,000.

Surface Roughness Evaluation of AZ31B Magnesium Alloy After Rough Milling Using Tools with Different Geometries

This paper presents the experimental results of a study investigating the impact of machining parameters on 3D surface roughness after rough, dry milling. The following 3D roughness parameters were analysed: Sa (arithmetic mean height), Sq (root mean square height), Sz (maximum height), Sku (kurtosis), Ssk (skewness), Sp (maximum peak height), and Sv (maximum pit height). Roughness measurements were made on the end face of the specimens. Additionally, 3D surface topography maps and Abbot-Firestone material ratio curves were generated. Carbide end mills with variable rake and helix angles were used in the study. Experiments were conducted on AZ31B magnesium alloy specimens using a contact-type profilometer. The machining process was conducted using the parameters of so-called high-speed machining. Three variable technological parameters were analysed: cutting speed vc, feed per tooth fz, and axial depth of cut ap. The results showed that the surface roughness of the rough-milled specimens depended to a great extent on the tool geometry and applied machining parameters. Feed per tooth was found to have the greatest impact on surface roughness parameters. Lower values of the analysed surface roughness parameters (and therefore higher surface quality) were obtained (in most cases) for the tools with a rake angle γ of 5° and a helix angle λs of 50°. The results provided both theoretical and practical knowledge about the achievable surface roughness after rough milling using tools with different tool blade geometry. It was shown that rough milling is an effective and efficient type of machining for the AZ31B alloy.

Prediction of thermal efficiency of double pass solar air heater having discrete multi V and staggered ribs

AbstractThis manuscript endeavors to elucidate a comprehensive analysis for the assessment of thermal efficiency in double pass solar air collectors augmented with fabricated roughness, instrumental in the generation of heated air for applications in heating and drying. The analytical procedure delineates comparisons between a smooth and a double‐sided, roughened absorber, characterized by discrete, multi V and staggered configurations of roughness. The analysis was performed for different roughness parameters including relative roughness width (W/w) from 4 to 8 and relative staggered rib size (r/e) from 1 to 4 and relative rib pitch (p′/p) from 0.2 to 0.8 while other parameters were kept constant. The research scrutinizes the impact of a constellation of parameters: the temperature rise coefficient (ΔT/I, varying between 0.002 and 0.02 K‐m²/W), Reynolds number (Re, spanning 2000–20,000), solar irradiance (I, ranging from 600 to 1000 W/m²), and the geometric variables of the artificial roughness, on both the thermal efficiency and efficiency enhancement factor of the collector. The study revealed that the roughened collector exhibits higher thermal efficiency compared to smooth collector for a similar condition. The extreme enhancement in thermal efficiency of the collector with roughness has been found to be 56.75% more than nonroughened collector for Re = 2000. A further observation was made that thermal efficiency has increased sharply for lower flow rate (Re &lt; 10,000) whereas for higher flow rates (Re &gt; 10,000), this increase becomes nearly asymptotic. In addition, the efficiency enhancement factor has also been found to increase with an increase in ΔT/I. A peak value of 2.321 has been found to be obtained for the efficiency enhancement factor for ΔT/I = 0.02 K‐m2/W and I = 1000 W/m2 as a result of the studies conducted.

Optimizing heat transfer in solar air heater ducts through staggered arrangement of discrete V‐ribs

AbstractThis research paper details an experimental study on airflow dynamics in a solar air heater. The heater's design incorporates unique, discrete V‐shaped ribs with staggered elements to enhance thermal performance. The study investigates the influence of various roughness parameters on flow characteristics. These parameters include a relative coarseness pitch (P/e) ratio of 12, a rib inclination angle (α) of 60°, a relative coarseness height (e/Dh) of 0.043, and a staggered element arrangement with a positioning ratio (p′/P) of 0.65. Additionally, the investigation includes scenarios with three gaps (Ng) between elements and a gap‐to‐rib width (g/e) ratio of 4. The research focuses on how changes to the Reynolds number, ranging from 3000 to 14,000, and alterations to the ratio of staggered element positioning to rib height (r/e), from 2 to 5, impact the flow dynamics. The outcomes indicate a significant boost in heat transfer performance, with the Nusselt number rising to 3.76 compared with a conventional smooth duct. The highest thermal efficiency recorded was 86%, at an r/e ratio of 3.5. These results underscore the potential of using discrete V‐ribs with staggered elements in rectangular ducts to improve heat transfer efficiency.

Effect of raceway surface topography based on solid lubrication on temperature rise characteristics of HIPSN full ceramic ball bearings

PurposeThis study aims to understand the influence of raceway surface topography on the temperature rise characteristics of silicon nitride (Si3N4) full ceramic ball bearing and improve its service life.Design/methodology/approachThe arithmetic average height Sa, skewness Ssk and kurtosis Sku in the three-dimensional surface roughness parameters are used to quantitatively characterize the surface topography of the raceway after superfinishing. The bearing life testing machine is used to test the Si3N4 full ceramic ball bearing using polytetrafluoroethylene (PTFE) cage under dry friction conditions, and the self-lubricating full ceramic ball bearing heat generation model is established.FindingsWith the decrease of Sa and Ssk on the raceway surface and the increase of Sku, the average height of the raceway surface decreases, and the peaks and valleys tend to be symmetrically distributed on the average surface, and the surface texture becomes tighter. This kind of raceway surface topography is beneficial to form a thin and uniform filamentous PTFE transfer film with a wide coverage area on the raceway surface based on consuming less cage materials and improving the temperature rise characteristics of hot isostatic pressing silicon nitride full ceramic ball bearings.Originality/valueThe research results provide a theoretical basis for the reasonable selection of Si3N4 ring raceway processing technology and have important significance for improving the working characteristics and service life of Si3N4 full ceramic ball bearings under dry friction conditions.

Effect of Shot‐Peening Process and Nanoparticle‐Added Lubricant on the Tribological Performance of Aluminium‐Based Sliding Bearing Material

ABSTRACTIn this study, it is aimed to increase the wear and fatigue performance of aluminium‐based sliding bearing material by using silver nanoparticles (AgNPs) added lubricant and shot‐peening process. The main purpose is to minimise the wear of the bearing material by penetrating AgNPs added lubricants into the rough surfaces formed by shot peening. Almen intensity, coverage and shot size parameters in the shot‐peening process were analysed in terms of hardness, surface roughness and fatigue strength. The shot‐peened aluminium bronze was subjected to wear experiments under dry, pure water and AgNPs added lubricant conditions. The wear test results were analysed in terms of friction coefficient, wear volume and surface roughness parameters, and the interaction of lubricant and shot‐peening parameters was evaluated. According to the results of the shot‐peening experiments, the Almen intensity was the most effective parameter in terms of hardness and surface roughness (91.62%). It was concluded that the hardness value was 8% higher at high Almen (12–14A) intensity compared with low Almen intensities, and the shot‐peening process could increase the fatigue strength by ~21 times. According to the wear tests, the most effective parameters were 4–6 Almen intensity and AgNP‐added lubricant.

Effect of Photoaging on the Structure, Optical Properties and Roughness of One-Shade Composite Restoratives.

The aim of the study was to evaluate changes in the degree of C=C conversion (DC%), chemical structure, optical properties and roughness of one-shade composites before/after photoaging. Τhe one-shade materials tested were Charisma Topaz One (CHT), Clearfil Majesty ES-2 Universal (MES), Essentia Universal (ESU) and Omnichroma (OMN), with G-aenial Anterior (CNA) serving as control. Specimens (2 mm thickness) were prepared and tested for DC% and chemical structure (ATR-FTIR spectroscopy), optical properties (L*a*b*-ΔΕ, translucency parameter-TP, opalescence parameter-OP, contrast ratio-CR and total transmittance-TT by UV-Vis spectroscopy) and roughness (Sa, Sz, Sdr, Sds and Sc by optical profilometry) before and after photoaging (Xe-arc weatherometer). Significant differences were found in DC% between top-bottom surfaces (ESU, OMN before; ESU, CNA after). Photoaging improved DC%, reduced ester peaks implying photodegradation, reduced L* (CHT, OMN, CNA), a* (CHT, CNA), b* (OMN, CNA), TP (all, except for MES), OP (only MES), CR (only MES, but an increase in CNA) and TT (CHT, OMN). OMN, CNA and MES demonstrated ΔΕ > 3.3. Photoaging significantly increased all roughness parameters in all materials, except for MES (Sz, Sdr, Sc) and OMN (Sdr). Although listed in the same group, significant differences were found in one-shade composites before and after photoaging. Several products were strongly affected by photoaging, demonstrating evidence of photodegradation, an increased roughness and color changes exceeding the clinically acceptable levels.

Redefinition of precision in finishing milling: Exploring the influence of tool margin and edge micro-radius on surface roughness

This article presents an analysis of microgeometry parameters, specifically the radius of cutting edge rounding, margin width, and rake angle influence on surface roughness in the milling of 7075 alloy. The study is underpinned by a set of 243 cutting tests conducted using 27 mills, each with a unique combination of geometry, feed, and radial infeed. Experimental mathematical models of the roughness parameters were developed. The findings reveal that while the influence of the cutting edge rounding radius on surface roughness is nonlinear and non-monotonic, the margin width has a monotonic effect and is the most significant factor impacting roughness.

A study on the repeatability of electroformed electrochemical gas driven micro-pump, using the surface roughness of cathode electrodes

ABSTRACT The objective of this paper was to analyse the effect of the surface roughness of a deposited copper cathode on repeatability for the discharge flow rate of an electroformed micro-pump. For this purpose, a measurement set-up was assembled using a glass gauge with a threshold sensor. Each test cathode was fitted into the micro-pump and the flow rate was measured three times. The value of the standard deviation of the measured flow rate was calculated as a criterion for the repeatability of the prepared micro pump. Finally, the covariance value and correlation coefficient between each surface roughness parameter and standard deviation of flow rate were calculated and compared. The results demonstrated that the Rz surface roughness parameter has the strongest relation with micro-pump flow rate repeatability using covariance analysis. Also, the auto-correlation length (ACL) that can describe the surface roughness using a correlation function has the most linear relation among all surface roughness parameters with a flow rate based on correlation analysis. SEM analysis and hydrogen bubble illustration were also reported.

Synthesis, Structural, and Optical Properties of Modified Poly(vinyl Chloride) Thin Films by Ethylenediamine Loaded with Metal Oxide Nanoparticles

AbstractPoly (vinyl chloride) (PVC) films modified with ethylenediamine (en) and doped by nanoparticles (TiO2, ZnO, NiO, and MgO). A mixture of 0.5 g PVC/en dissolved in THF and 0.01 wt % of nanoparticles were used in doping PVC to produce the nanocomposite films. All modified PVC films were characterized by different analysis techniques such as Fourier Transform Infrared (FTIR), Nuclear Magnetic Resonance Spectrometer (NMR), diffusive reflectance spectroscopy (DRS), X‐ray diffraction analysis (XRD), and scanning electron microscopy (SEM). The DRS was used to analyse the scattered IR energy of the samples at wavelengths between (250–1350 nm). The optical properties and oscillator strength were also studied, the transmittance and reflectance values declined for the PVC films, and the absorption coefficient was observed between (79–89 %). The direct energy gap decreased from 4.6 to 1.9, and the indirect energy gap reduced from 4.3 to 1.9. The XRD exhibited a semi‐crystalline structure and the SEM test exhibited a porous structure of all samples. The Urbach energy was increased from 0.8772 eV to 14.712 eV, single oscillator energy ( ) was also increased from 6.38 eV to 13.69 eV and the dispersion energy increased from 23.40 eV to 70.63 eV. Moreover, the surface roughness parameters Ra and Rq of the PVC films in modified and doping were increased from 3.86 nm to 8.14 nm, and 5.08 nm to 10.10 nm respectively. So, PVC results show increased optical properties after modification with en and doping by NPs are used in the light conversion and aerospace industries.

Microbiological Evaluation of Thermoplastic PETG Dental Appliances Related to Surface Characteristics.

(1) Background: The adhesion and microbiological behaviour of thermoplastic PETG dental appliance surfaces is governed by roughness parameters. The aim of this research was to evaluate the antibiofilm activity of alkaline peroxide-based disinfectant in Candida albicans biofilms on thermoplastic PETG, related to artificial ageing and surface characteristics, on multiscale levels. (2) Methods: In the present study, two PETG materials were investigated: Crystal® (Bio Art Dental Equipment, Sao Carlos, Brazil), noted as C, and Duran® (Scheu-Dental GmbH, Iserlohn, Germany)-noted as D. Half of the specimens were thermally cycled (TC), resulting in four sample groups, as follows: C, CTC, D, and DTC. Surface roughness was evaluated on different scale topographies. The biofilms were grown on the surfaces. An alkaline peroxide-based disinfectant was used. Statistical analyses were performed. (3) Results: Related to nanoroughness, there are insignificant differences among materials or related to thermocycling. More irregular surfaces are associated with larger grain sizes. After thermocycling, micro-roughness values increase. Disinfectant activity decreases the amount of biofilm developed on the surfaces, significantly in the two groups, but is not correlated to the material and artificial ageing. (4) Conclusion: The impact of surface roughness (Ra) on biofilm constitution is controlled by different scale topographies.

Multi-scale morphological analysis of brake lining surface and load-bearing arrangement in the contact

In the case of braking, a diversity of friction mechanisms occurs at the interface, caused by the heterogeneity of the composition, properties, and thermal phenomena. After friction, the obtained surfaces of the brake lining materials are highly heterogeneous. Load-bearing plates which are also called contact plateaus are formed with a compacted third body and constitute the sites of energy dissipation and sliding velocity accommodation. Their arrangement and preferential localizations in the contact constitute a key factor for the understanding of friction-induced phenomena and braking performance. Within this framework, a morphological characterization method has been set up based on several measurement techniques to explore the macroscopic and microscopic contact situation of the pad-disc system. The results show that exploiting Abbott curve parameters combined with roughness parameters is an effective way to give a detailed and comprehensive morphological description of the brake pad friction surface. It can be seen that the contact plateaus have preferential locations which give a particular load-bearing arrangement in the pad-disc interface which can be explained by friction and wear mechanisms. Results reveal also the main encountered difficulties, especially regarding the significance of scales and parameters describing the morphology of the friction material surface and the load-bearing plates disposition.

A Fast Numerical Approach for Investigating Adhesion Strength in Fibrillar Structures: Impact of Buckling and Roughness

This study presents a numerical investigation into the adhesion strength of micro fibrillar structures, incorporating statistical analysis and the effects of excessive pre–load leading to fibril buckling. Fibrils are modeled as soft cylinders using the Euler–Bernoulli beam theory, with buckling conditions described across three distinct states, each affecting the adhesive properties of the fibrils. Iterative simulations analyze how adhesion strength varies with pre–load, roughness, number of fibrils, and the work of adhesion. Roughness is modeled both in fibril heights and in the texture of a rigid counter surface, following a normal distribution with a single variance parameter. Results indicate that roughness and pre–load significantly influence adhesion strength, with excessive pre–load causing substantial buckling and a dramatic reduction in adhesion. This study also finds that adhesion strength decreases exponentially with increasing roughness, in line with theoretical expectations. The findings highlight the importance of buckling and roughness parameters in determining adhesion strength. This study offers valuable insights into the complex adhesive interactions of fibrillar structures, offering a scalable solution for rapid assessment of adhesion in various rough surface and loading scenarios.

Oil Plant Pomace as a Raw Material in Technology of Sustainable Thermoplastic Polymer Composites

The design of composites offers extensive opportunities for controlling parameters and utilizing diverse materials, including those sourced from recycling or waste streams. In this study, biocomposites were developed using high-density polyethylene (HDPE) and pomace derived from oilseed plants such as evening primrose, gold of pleasure, rapeseed, and sunflower seeds, mixed in a 1:1 ratio. These biocomposites were evaluated for their structural, mechanical, morphological, and thermal properties, as well as their vulnerability to overgrowth by cellulolytic fungi. The results indicate that incorporating plant waste into HDPE reduces thermal stability while increasing water absorption and thickness swelling. Additionally, the biocomposites showed enhanced fungal growth, which may improve their biodegradability. Notably, the PE_EP composite, derived from evening primrose pomace, did not show significant differences in surface roughness and MOE parameters compared to pure polyethylene. In the case of PE_R composite, an increase in MOE was observed while maintaining the MOR parameter compared to pure PE. Although generally the mechanical properties of composites were lower compared to pure polyethylene, the findings suggest that with further optimization, oil plant pomace can be a valuable raw material for producing biocomposites suitable for various industrial applications, thereby contributing to sustainability and effective waste recycling.

Integrated multi-objective optimization of rough and finish cutting parameters in plane milling for sustainable machining considering efficiency, energy, and quality

Plane milling is one of the most prevalent methods in metalworking, recognized for its potential to uncover energy-saving opportunities by optimizing cutting parameters. However, existing research on cutting parameters optimization primarily adopts a phased independent optimization approach, with some studies focusing on rough milling parameters and others on finish milling parameters under predetermined allowances. These research methods lack integrated optimization for both rough and finish milling parameters, leading to suboptimal outcomes. To address this issue, this paper proposes an integrated multi-objective optimization method for both rough and finish cutting parameters in plane milling. The aim is to achieve sustainable machining by considering efficiency, energy consumption, and quality. Specifically, the research accomplishes three key objectives: (1) developing detailed models for the efficiency, energy, and quality of plane milling; (2) presenting an integrated multi-objective optimization model and approach for determining rough and finish cutting parameters in plane milling; (3) conducting a specific case study to validate the effectiveness and feasibility of the proposed model and approach. Experimental findings demonstrated that optimizing cutting parameters in the plane milling process through an integrated approach can reduce processing time by 19.37%, decrease energy consumption by 16.88%, and significantly improve the surface roughness of the workpiece by 27.07% compared to traditional empirical methods. Furthermore, compared to independent optimization schemes, processing time is reduced by 2.99%, energy consumption is lowered by 4.72%, and surface roughness is improved by 13.16%.

Electromagnetic wave scattering simulation from precision grinding SiC surface under the influence of suspended micro-particles

ABSTRACT In a precision machining environment, suspended particles in the air have a non-negligible effect on visual roughness measurement results. To address this issue, this paper analyzes the influence of particles on the visual roughness measurement from theoretical derivation and numerical simulation, respectively. Firstly, based on the Lambert-Beer and the light scattering principles, the propagation equation of incident light under the joint action of suspended particles and rough surfaces is derived. Then, a numerical simulation model is designed, and the theoretical equations are verified by simulation experiments. The influence of particle material, particle size (D), particle concentration (N), light wavelength (λ), and SiC surface roughness (R a ) on the average electric field magnitude of the energy-acquisition boundary are analysed based on the simulation experiments. The theoretical derivation shows that the average electric field magnitude of the energy-acquisition boundary is mainly influenced by particle state and rough surface state. The simulation experiment results show that both the particle parameters and the rough surface parameters are consistent with the theoretical derivation. As R a increases, the effect of N on the measurement results decreases. The results reveal the influence mechanism of suspended particles on the visual roughness measurement results and provide a basis for improving visual roughness measurement accuracy.

A new numerical simulation method of 3D rough surface topography with coupling 3D roughness parameters Sdr, Sdq, Spd, Spc, and characteristic functions

The existing surface topography modeling methods based on random process theory make it difficult to realize the coupling of three-dimensional roughness parameters Sdr, Sdq, Spd, and Spc in ISO25178, which are related to the friction and lubrication performance of parts. The paper proposes constraints set for the structure of spatial features in height matrix discrete points during the random switching process, and the accurate coupling of parameters Sdr, Sdq, Spd, and Spc with characteristic functions is achieved by the improved random switching system. The new method is applied to simulate four kinds of finishing surface topography numerically, and the results show that the relative errors of these four parameters are effectively reduced from 5–110 % to 1 %.