3D Roughness Research Articles

Optimization and machinability evaluation for WEDM of austempered ductile iron

Abstract Wire electrical discharge machining (Wire EDM) is a non-contact CNC machining that removes material from a workpiece with electrical sparks. Optimization of parameters involved in wire EDM is essential for better operational economics and energy usage. The major goal and objective of this research are to assess the machining parameters, like surface roughness Ra, material removal rate MRR, and hardness HV by experimental investigation utilizing the wire cut EDM machine and austempered ductile iron (ADI) as the work material. An artificial neural network (ANN) has been employed to create a prediction model using experimental data. The Aquila optimization approach is then used to obtain the ideal operating parameters. With Aquila optimization, the predicted optimum values for MRR, Ra, and Hardness are 3.529 mm3/min, 1.966 µm, and 367 HV, respectively, when the input parameters are pulse ton 16 µs, pulse-toff time toff 14 µs, servo voltage 50 V, and current 3 A. Finally, SEM and 3D roughness analysis have been carried out to study surface morphology and material removal mechanism.

3D micromorphological reconstruction and roughness characterization of wood surface based on sequence images

A novel non-contact optical inspection technique is proposed to precisely reconstruct the three-dimensional surface structure of wood and evaluate its roughness. The feasibility of using image fusion techniques to characterize the 3D roughness of wood surfaces is explored by combining high-resolution serial image acquisition techniques with advanced data processing methods. The work focuses on examining various cut surfaces of three distinct wood species: Larch, Catalpa, and Toona sinensis. The proposed 3D roughness parameters are verified using 3D reconstruction and precise measurements. The experimental results demonstrate that the proposed method exhibits strong adaptability in measuring wood surface roughness and achieves a high degree of consistency with the results obtained from traditional digital microscope systems. This study not only validates the possible use of multilayer sequence image fusion technology in measuring wood roughness, but also establishes a solid basis for the creation of 3D assessment criteria for wood surface roughness and associated inspection systems.

Synergetic effect of hybrid surface treatment on the mechanical properties of adhesively bonded AA2024-T3 joints

ABSTRACT Improving the surface properties of AA2024-T3 aluminium alloys is crucial for achieving durable and sustainable joints. For this purpose, AA2024-T3 alloys were first sandblasted at 4, 5 and 6 bar pressures using aluminium oxide and glass sphere abrasives. Then, the sandblasted samples were subjected to the chemical surface treatment resulting in a hybrid surface process. The surface properties of sandblasted and hybrid surface-treated AA2024-T3 alloys were characterised by 3D image analysis, contact angle and roughness measurement. Additionally, single-lap joints were fabricated using adhesives with low and high viscosity. The effect of changes in the viscosity of adhesives and the surface properties of the AA2024-T3 on the mechanical properties of the joints has been analysed in detail. It was found that both sandblasting and hybrid surface treatments applied to AA2024-T3 alloys caused significant improvement in the mechanical properties of the joints. AA2024-T3 alloys, which were chemically surface treated after being sandblasted with glass spheres at 6 bar pressure, were joined using low and high viscosity adhesives, and the failure load of these joints increased by approximately 110% and 68%, respectively, compared to untreated samples. In the case of aluminium oxide usage, the increase rates were determined to be 93% and 43%.

A New Numerical Simulation Method for 3D Rough Surface Topography of Shot Peening Parts with Specified 3D Roughness Spatial Parameters

A New Numerical Simulation Method for 3D Rough Surface Topography of Shot Peening Parts with Specified 3D Roughness Spatial Parameters

Characterization on Flaking of Rammed Earthen Sites Using SMO Algorithm and Surface Topography Analysis: A Case Study of Jiaohe Ruins

There are a large number of rammed earthen sites in northwest China. For thousands of years, earthen sites have developed a series of deterioration types that include surface weathering, sapping, cracks, collapses, gullies, and so on. Surface weathering is a highly destructive type of soil deterioration which erodes the sites all the time. Flake peeling (flaking) is one of the main manifestations of weathering. In order to prevent flaking more scientifically and efficiently, it is necessary to quantitatively evaluate its development stage and degree. In this article, the Vajra Pagoda of Jiaohe Ruins was selected as the research area, and we explored how to use GIS to analyze the surface topography of 3D scanning data. Meanwhile, using the sequential minimum optimization (SMO) algorithm, the authors effectively identify the crust and original wall (wall outcroppings following the detachment of crust) in the evolution of flaking. Finally, the 3D roughness of the four facades was calculated. The calculations show that the roughness parameters D and R s can well characterize the development of flaking. In a period of flaking development, the change rule of D and R s first increases and then decreases. This study proves that it is feasible to quantify the development degree of flaking employing morphological characteristic parameters. Furthermore, the results of the study provide a basis for determining the degree of deterioration of the sites in future heritage management efforts, leading to more rational and efficient conservation.

Performance evaluation of cold plasma and h-BN nano-lubricant multi-field coupling assisted micro-milling of aluminum alloy 6061-T651

Micro-milling has been employed in various fields due to its efficiency, flexibility, material, and structural versatility in the machining of small and high-quality parts. However, when micro-milling highly plastic aluminum alloys, it is difficult to produce a smooth surface due to the easy sticking of tools. To solve this problem, a multi-energy field coupling method of adding nano-lubricant to the micro-milling area by minimum quantity lubrication (MQL) and modifying the aluminum alloy by cold plasma (CP) was introduced. In this paper, the experiments of CP and h-BN nano-lubricant minimum quantity lubrication (NMQL) multi-field coupling assisted (CPNMQL) micro-milling of aluminum alloy 6061-T65 were carried out to analyze 3D surface roughness (Sa), tool texture, milling forces (Fx and Fy), and surface morphology. The results revealed that the CP could increase the surface microhardness and improve material removal rate; Cottonseed oil with h-BN nanoparticles exhibited superior lubricating properties; The milling forces Fx and Fy were significantly reduced; Sa (0.029 µm) under CPNMQL condition decreased by 60 %, 72.1 %, 27.5 %, and 53.2 % comparing to dry (0.104 µm), NMQL (0.04 µm), and CP (0.062 µm) conditions. In addition, the smallest and most uniform tool mark texture height and depth of 0.038 µm was obtained under CPNMQL condition, a 76.3 % reduction over dry condition.

Grinding of C/SiC ceramic matrix composites: Influence of grinding parameters on tool wear

C/SiC Ceramic Matrix Composites (CMCs) have been identified as a key material for improving high-speed braking systems and aerospace components as they offer low density, and high specific strength at high temperatures. Grinding is often used for the machining stage due to the high hardness, heterogeneity, and brittle nature of CMSs. Previous studies have explored the effect of grinding parameters, but most of them do not indicate whether they have used the same grinding wheel for all tests. In fact, there is limited understanding of how wear impacts process performance over the grinding wheel's lifespan. In this work, the effect of grinding wheel wear on cutting forces is addressed and grinding wheel topography is analyzed with the objective of identifying a parameter that allows to quantify grinding wheel wear in a non-destructive way. Results have shown that, after a short conditioning stage, cutting forces increase approximately linearly with the machined length. For the machining conditions analyzed, normal forces increase 200 % in the first machined meter (first stage), then rise 17 % per meter thereafter (second stage). Tangential forces rise 300 % in first meter and then climb 27 % per meter subsequently. In this second stage, force ratio approaches a constant value and the generation of flat surfaces on the diamond grains is the dominating wear mechanism. Under such conditions, 3D surface roughness parameters Sa, Sq, Spk and Sku have been proven to be useful for monitoring wheel wear.

3D Optical and Mechanical Roughness Measurements of Complex and Irregular Structures on the Basis of Polypropylene Moldings

3D Optical and Mechanical Roughness Measurements of Complex and Irregular Structures on the Basis of Polypropylene Moldings

3D Roughness Prediction Modeling and Evaluation of Textured Liner of Piston Component-Cylinder System

In this study, a machine vision method is proposed to characterize 3D roughness of the textured surface on cylinder liner processed by plateau honing. The least absolute value (L∞) regression robust algorithm and Levenberg-Marquardt (LM) algorithm are employed to reconstruct image reference plane. On this basis, a single-hidden layer feedforward neural network (SLFNN) based on the extreme learning machine (ELM) is employed to model the relationship between high frequency information and 3D roughness. The characteristic parameters of Abbott-Firestone curve and 3D roughness measured by a confocal microscope are used to construct ELM-SLFNN prediction model for 3D roughness. The results indicate that the proposed method can effectively characterize 3D roughness of the textured surface of cylinder liner.

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.

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 %.

The role of manufacturing-induced texture on the tribological performance of cold work tool steels

Manufacturing operations produce surface characteristics that, although stochastic, can significantly affect functionality, especially in forming tools, impacting contact and lubrication conditions during operation. This study investigates the influence of stochastic microtextures resulting from milling on the tribological performance of cold work tool steels with two different carbon contents (0.8 and 2 wt%). Different surface textures were observed resulting from the different C contents, with 3D roughness parameters indicating rougher surfaces for the 2.0% wt. C steel. Tribological behavior was assessed using the strip drawing test to analyze friction, wear coefficients, and wear mechanisms. Surface analysis before and after testing was executed employing SEM, EDX, and CLSM, with CLSM also used to determine 3D roughness parameters of the worn tracks. Post-test macrographic analyses and 2D roughness measurements were conducted on the pulled sheets. Tribological test data revealed lower friction and wear coefficients for the 2.0 wt% C tool steel, with susceptibility to abrasion wear, while the 0.8 wt% C tool exhibited a higher tendency towards adhesion wear. Post-test analysis suggested smoother surfaces for the 2.0 wt% C steel compared to the 0.8 wt% C steel. Macrographic analysis showed no visible wear marks on sheets tested with the 2.0 wt% C steel, contrasting with wear grooves visible on sheets pulled against the 0.8 wt% C steel. Additionally, 2D roughness measurements indicated higher roughness after pulling against the 0.8 wt% C tool compared to the 2.0 wt. C tool. Overall, the study demonstrates that manufacturing-induced textures without the need of post-manufacturing texturing influence the tribological performance of the evaluated steels, opening an avenue to be explored to improve the tribological performance of forming tools.

Deep-learning-assisted sidewall profiling white light interferometry system for accurately measuring 3D profiles and surface roughness on the groove sidewalls of precision components.

The accurate measurement of surface three-dimensional (3D) profile and roughness on the groove sidewalls of components is of great significance to diverse fields such as precision manufacturing, machining processes, energy transportation, medical equipment, and semiconductor industry. However, conventional optical measurement methods struggle to measure surface profiles on the sidewall of a small groove. Here, we present a deep-learning-assisted sidewall profiling white light interferometry system, which consists of a microprism-based interferometer, an optical path compensation device, and a convolutional neural network (CNN), for the accurate measurement of surface 3D profile and roughness on the sidewall of a small groove. We have demonstrated that the sidewall profiling white light interferometry system can achieve a measurement accuracy of 2.64 nm for the 3D profile on a groove sidewall. Moreover, we have demonstrated that the CNN-based single-image super-resolution (SISR) technique could improve the measurement accuracy of surface roughness by over 30%. Our system can be utilized in cases where the width of the groove is only 1 mm and beyond, limited only by the size of the microprism and the working distance of the objective used in our system.

The Laser Scanner Technique: A Tool for Determining Shear Strength Parameters of Rock Mass Discontinuities

When evaluating the shear strength of rock mass discontinuities, certain challenges arise due to the difficulty in quantifying the roughness characteristics of surfaces and the strength of asperities. Recent research has focused on enhancing techniques for assessing these characteristics and exploring the application of laser scanning to aid in evaluating discontinuity features. The analysis of reflectivity values (I) obtained through a laser scanner survey presents an efficient method for assessing mechanical characteristics, such as joint compressive strength (JCS). Reflectivity measurements demonstrate correlations with Schmidt hammer rebound values (r). The laser scanner technique would enable the measurement of JCS without the direct application of the Schmidt hammer on rocks in areas where rebound values (r) measurements are unavailable. The use of a laser scanner allows for the acquisition of high-precision geometrical information concerning the 3D roughness and anisotropy of rock surfaces. In this study, an innovative technique was introduced that utilizes laser scanner data from six previous experimental surveys conducted on rock formations in Southern Italy. This technique facilitates the evaluation of roughness profiles, considering potential variations along kinematically admissible sliding directions, allowing for the estimation of the Joint Roughness Coefficient (JRC). This new methodology aids in evaluating the parameters of Barton’s equation to determine the strength characteristics of rock mass discontinuities.

Scale effects and spatial distribution characteristics of 3D roughness of natural rock fracture surfaces: statistical analysis

Scale effects and spatial distribution characteristics of 3D roughness of natural rock fracture surfaces: statistical analysis

Criteria for Evaluating the Tribological Effectiveness of 3D Roughness on Friction Surfaces

A new technique for finishing the surfaces of friction pairs has been proposed, which, in combination with the original test method, has shown a significant influence of the initial roughness configuration (surface texture) on friction and wear. Two types of finishing processing of the shaft friction surfaces were compared, and it was found that the friction and wear coefficients differ by more than 2–5 and 2–4 times, respectively. Based on a new methodology for analyzing standard roughness parameters, the tribological efficiency criteria (in the sense of reducing friction and wear) are proposed for the initial state of the friction surface of a radial plane sliding bearing shaft relative to the friction direction, which is consistent with its frictional characteristics. Comparison of the laboratory test results with the surface tribological efficiency criteria showed that these criteria are very promising for controlling existing technologies and optimizing new technologies for friction surface finishing in various friction systems.

Dominant heat transfer mechanism with conical roughness in a cubical box in turbulent Rayleigh–Bénard convection

In the present study, we numerically investigate the effect of Prandtl number on the heat transfer mechanism in turbulent Rayleigh–Bénard convection inside a cubical box endowed with conical roughness elements. The Rayleigh number is kept fixed at Ra=108, while the Prandtl number (Pr) varies from 1 to 50. In contrast to the monotonic increasing trend of the Nusselt number (Nu∼Pr0.27) in the two-dimensional (2D) roughness explored previously [Sharma et al., “Influence of Prandtl number in turbulent Rayleigh-Bénard convection over rough surfaces,” Phys. Rev. Fluids 7, 104609 (2022)], it assumes an invariant behavior (∼Pr0.012) for three dimensional (3D), though it is approximately 50% higher than its smooth counterpart. Flow intensity, measured in terms of Reynolds number (Re), drops with increasing Pr showing consistently lower magnitude for the 3D configuration. The addition of roughness elements is observed to disrupt the preferred orientation of large-scale circulation (LSC). The effect is predominant for lower Pr, where the roughness interferes most with the natural bias of LSC toward the diagonal planes of the cubical box. The analysis of plume statistics reveals that both coverage and intensity of plumes are augmented for the roughened cell. Increased homogeneity in the flow at higher Pr is reflected by the emergence of a more pronounced and distinguishable peak in probability density functions of temperature and velocity. Temporal spectra and variance data substantiate augmented intensity of fluctuations in the rough cell, while behavioral differences in the flow at different Pr are elucidated by using cross correlation of vertical velocity and temperature fluctuations.

Regeneration Effect of a New Bio-Based Warm-Mix Rejuvenator on Performance and Micro-Morphology of Aged Asphalt.

The use of warm-mix recycling technology can reduce the mixing temperature and the secondary aging of binders in reclaimed asphalt pavement (RAP), which is one of the effective ways to recycle high-content RAP. In this study, the penetration, softening point, ductility, and viscosity were used to characterize the conventional physical properties of aged asphalt after regenerating, while a dynamic shear rheometer (DSR), force ductility tester (FDT), and atomic force microscope (AFM) were used to evaluate the rheological performance and micro-morphology of aged asphalt incorporating a new bio-based warm-mix rejuvenator (BWR) and a commercial warm-mix rejuvenator (ZJ-WR). The regeneration mechanism of warm-mix rejuvenators on aged asphalt was analyzed by Fourier transform infrared spectroscopy (FTIR). The results show that the new bio-based warm-mix rejuvenator can restore the conventional physical properties, low-temperature performance, and micro-morphology of aged asphalt with an appropriate dosage, but it has a negative effect on high-temperature performance. In comparison with 2D area parameters, 3D roughness parameters were more accurate in evaluating the variation in micro-morphology of aged asphalt after regeneration. The FTIR analysis results indicate that both the new bio-based warm-mix rejuvenator and the commercial warm-mix rejuvenator regenerate aged asphalt by physical action, and AS=O and AC-H values are more reasonable than the AC=O value for the restoration evaluation of aged asphalt. And the new bio-based warm-mix rejuvenator has a better regeneration effect on the performance and micro-morphology of aged asphalt than the commercial warm-mix rejuvenator.

The Effect of Non-Invasive Treatment Techniques on the Color Masking Ability and Surface Roughness of Induced Enamel Lesions (An in vitro Study).

The aim of this in vitro study was to evaluate the effect of the resin infiltration technique and remineralization of induced enamel caries with fluoride solution on the color masking of white spot lesions and surface roughness. A total of 45 sound teeth were used in this study. All the teeth were sectioned along the long axes into two halves, lingual and buccal to get 90 specimens. All specimens were immersed in a demineralized solution for 7 days. The specimens were divided randomly into three equal groups (n = 30) according to the type of treatment; Group 1 (n = 30) was treated with fluoride varnish (Clinpro); Group 2 (n = 30) was treated by resin infiltration (Icon); and Group 3 (n = 30) was used as a control group with no treatment. The color and surface roughness were measured three times at baseline (T1), directly after induction of artificial white spot lesions (WSLs) (T2), and directly after application of the treatment options (T3). The colors were measured using a portable reflective spectrophotometer and the 3D surface roughness was measured using a Light Sectioning Vision System. Data were collected and statistically analyzed using T test and Mann-Whitney U test. Surface roughness was almost equal in the study groups with no statistically significant differences reported. Icon showed slightly higher color scores than that of ClinPro. The Icon produced favorable esthetic results compared to the fluoride therapy while no significant differences were reported regarding the surface roughness.

The impact of random 3D roughness on natural convection along a vertical plate

This study simulates natural convection on vertical surfaces with random roughness under Reynolds number conditions of 106. The roughness of these surfaces is arranged randomly, making the simulation closer to real-world conditions. To handle natural convection in low-speed compressible flows, our solver treats the fluid as compressible to solve the complete Navier-Stokes equations. Observations show that adjacent peaks generate vortices, limiting the heat circulation between valleys and the surrounding cooler air. Influenced by buoyancy, the slower upstream flow over rough surfaces stabilize heat transfer in the valleys and slightly accelerates the flow near the peaks, resulting in higher local Nusselt numbers on the peaks. As the flow velocity increases, the disturbances caused by rough elements become more pronounced, leading to a more chaotic flow pattern downstream, thereby affecting the overall heat transfer. This phenomenon becomes more pronounced with increasing surface roughness. The overall distribution of Nusselt numbers shows higher and more concentrated values upstream compared to downstream. Despite local Nusselt numbers on rough surfaces generally being higher than those on smooth surfaces, the average Nusselt numbers are lower on the rough surfaces due to the longer time required for heat transfer on rough surfaces.