Bearing Area Curve Research Articles

Characterization and Correlation Analysis of Surface Topography in Ball-End Milling

Abstract Surface texture is the most commonly used parameter for the quantitative characterization of surface topography. It is important for the study of the topography characteristics and functional properties of surfaces. In this paper, the surface topography characteristics, surface texture parameters, and change rule of the bearing area curve when the cutting vibration of the adjacent teeth of the ball-end milling cutter is asymmetric were analyzed, and the correlation between the inflection points and the surface texture parameters of the bearing area curve were studied according to the improved correlation analysis model. This study provides essential insights into the mechanism that drives the formation of the surface topography of ball-end milling and the intrinsic characteristic laws of the surface topography.

A New Approach for Determining Rubber Enveloping on Pavement and Its Implications for Friction Estimation

The depth to which the pavement texture is enveloped by the tire tread rubber (d) is an important parameter related to contact performance. This study presents a new method (S-BAC), which relies on the ratio between the real contact area and the nominal tire-pavement contact area (S) and the bearing area curve (BAC), to measure the depth on pavements. The tire-pavement contact was simulated by contact between a non-patterned rubber block and pavement specimens. After analyzing the affecting factors, the new method was compared with previous methods by the d values and the application on the relationship between pavement texture parameters and friction. The results reveal that though there is a linear regression between the d obtained with the S-BAC and previous methods, the d values obtained with different methods differ. Applying the S-BAC method can strengthen the relationship between texture parameters and friction more than other methods.

AN INVESTIGATION ON MEAN ROUGHNESS DEPTH AND MATERIAL EROSION SPEED DURING MANUFACTURING OF STAINLESS-STEEL MINIATURE RATCHET GEARS BY WIRE-EDM

This paper presents the results of an investigation conducted on wire electric discharge machining (wire-EDM) of miniature ratchet gears. Effects of three important process parameters spark duration, ‘Ton’, spark-off-duration ‘Toff’, and wire tension ‘WT’ on surface quality, i.e., mean roughness depth ‘Rz’ and productivity, i.e., material erosion speed ‘MES’, have been investigated by conducting seventeen experimental trials. Both Ton and Toff have been identified as the significant parameters. Further, an optimization of wire-EDM parameters resulted in simultaneously best compromise values of Rz 5.30 µm and MES 6.75 mm/min and is achieved the following cutting regime: Ton 1.5 µs, Toff 42.5 µs, and WT 1500 g. At the end, surface quality study has been conducted to evaluate the tribological fitness of the miniature ratchet gear machined at optimum combination of wire-EDM parameter values. It was investigated that the generation of uniform and shallow craters on the flank surfaces of ratchet gear machined at optimum values of parameters, imparted smoother bearing area curve and lower coefficient of friction. The profile and flank surface of the ratchet gear also found free from cracks, burrs, and dirt.

Bearing area curve based partitioning for the verification of theoretical supplemental geometry on additively manufactured lattice structures

Bearing area curve based partitioning for the verification of theoretical supplemental geometry on additively manufactured lattice structures

Influence of the Duty Cycle of Pulse Electrodeposition-Coated Ni-Al2O3 Nanocomposites on Surface Roughness Properties

In this study, the viability of duty cycle variation was explored as a potential method to improve the mechanical and surface roughness properties of Ni-Al2O3 nanocoatings through pulse electrodeposition. The areal and surface roughness properties of nanocomposite pulse electrodeposition-coated materials with varying duty cycles from 20% to 100% was studied with the analysis of bearing area curves and power spectral densities. Results demonstrate that with decrease in duty cycle, there was an enhancement in aerial roughness properties from 0.348 to 0.195 µm and surface roughness properties from 0.779 to 0.245 µm. The change in surface roughness was due to grain size variation, resulting from the varying time intervals during pulse coatings. This increase in grain size with the change in duty cycle was confirmed with the scanning electron microscope. In addition, an increase in grain size from 0.32 to 0.92 µm with an increase in duty cycle resulted in a decrease in nanohardness from 4.21 to 3.07 GPa. This work will provide a novel method for obtaining Ni-Al2O3 nanocomposite coatings with improved surface roughness and hardness properties for wider industrial applications.

Effectiveness of using liquid nitrogen cryogen in grinding to enhance the grinding performance of hard steel

Grinding generates a lot of heat in the grinding zone area during operation. Therefore, it is important to keep the temperature under control by using various cutting fluids to get a good ground surface quality. The existence of a stiff air layer surrounding the abrasive wheel is known to waste most of the cutting fluid supply in the interface area between the abrasive wheel and workpiece. Due to the high grinding speed, stiff air layers prevent cutting fluids from entering the interface area. Hence, to enhance the grinding performance, cryogenic cooling has been introduced to improve the penetration into the stiff air layer. The current work investigates the grindability of the ground surface of AISI D2 tool steel under different environments: dry, wet, and cryogenic, regarding grinding forces (i.e. tangential and normal force), specific grinding energy, and surface characterisation. This paper also proposed a method to evaluate image-based Abbott–Firestone curve (bearing area curve) parameters to characterise the ground surface topography. Significant reductions in grinding forces (64%–67% and 44%–50% in Ft, 54%–58% and 34%–39% in Fn), low specific grinding energy (64%–67% and 44%–50%), decrease in surface roughness (46%–51% and 30%–36% in Ra, 37%–41% and 31%–35% in Rz), improved 2D and 3D roughness profiles and higher bearing area ratio (89.54%) were observed at 40 µm downfeed in cryogenic cooling environments compared to dry and wet environments, respectively. Thus, observations show the importance of cryogenic cooling across the experimental domain.

The dynamic interplay of dietary acid pH and concentration during early-stage human enamel and dentine erosion

Dental erosion continues to be a significant global health concern affecting nearly 30% of adults world-wide. With increasing soft drink consumption predominantly driving its prevalence, strategies for prevention and control are often implemented when erosion is severe, or rates are high in the populace. While factors affecting dental erosion such as pH on enamel has received much attention, the effect of dietary acid concentration when factored out to a commercially available pH has yet to be determined. Furthermore, understanding these effects on dentine, which is known to be more susceptible to erosion than enamel can unravel structure property relationships between acid characteristics and hard tissue types. This study aimed to develop structure-property relationships between dietary acid concentration, and pH, on the nano-textural and nano-mechanical properties of human enamel and dentine during short-term simulated drinking. To achieve this, a novel sample preparation methodology and analysis approach was developed by applying atomic force microscopy (AFM) in quantitative imaging mode. This enabled simultaneous measurement of enamel and dentine morphology and mechanical properties. Flow-cells were used to simulate drinking, exposing polished and smear layer free human enamel and dentine to 30 s repeated cycles of unbuffered citric acid 6% (pH = 1.88) and 1% (w/v) (pH = 2.55) and commercially available buffered pH = 3.8 states, for up to 180 s. The same 50 µm × 50 µm area of specimen morphology was analysed using in-house developed nanotextural analysis using the bearing area curve (BAC) with a focus on roughness (Ra), normalised peak (PA) and valley areas (VA). Mechanical properties were simultaneously measured for stiffness (N/m) after each 30 s. While all studies agree pH is a major factor in the erosion of enamel, here its dominance over the treatment time varied, with concentration surpassing the importance of pH after initial acid contact. Conversely, dentine erosion showed concentration-dependent changes in morpho-mechanical properties only. These results not only highlight the dynamic process of erosion, but how the interplay between acid characteristics and dental tissue type impact the progression of very early-stage erosion.

Hypothesis tests with functional data for surface quality change detection in surface finishing processes

This work is concerned with providing a principled decision process for stopping or tool-changing in a surface finishing process. The decision process is supposed to work for products of non-flat geometry. The solution is based on conducting hypothesis testing on the bearing area curves from two consecutive stages of a surface finishing process. In each stage, the bearing area curves, which are in fact the nonparametric quantile curves representing the surface roughness, are extracted from surface profile measurements at a number of sampling locations on the surface of the products. The hypothesis test of these curves informs the decision makers whether there is a change in surface quality induced by the current finishing action. When such change is detected, the current action is deemed effective and should thus continue, while when no change is detected, the effectiveness of the current action is then called into question, signaling possibly some change in the course of action. Application of the hypothesis testing-based decision procedure to both spherical and flat surfaces demonstrates the effectiveness and benefit of the proposed method and confirms its geometry-agnostic nature.

Intimate contact development for automated fiber placement of thermoplastic composites

The consolidation step in the automated fiber Placement (AFP) of thermoplastic composites is crucial for development of interlaminar bonding strength. Two mechanisms contribute to the interlaminar bond strength development in the interface between the incoming tow and the substrate: (a) the development of intimate contact between the two surfaces and (b) the formation of a fusion bond across those contacting surfaces known as healing. So far, a number of different theoretical intimate contact models have been proposed in the literature to study intimate contact development for different manufacturing processes. However, very limited experimental methods are available to measure degree of intimate contact. To fill this gap, a new experimental approach based on topology of the tape surface is introduced to quantify the degree of intimate contact for the AFP process. The new approach is based on the Bearing Area Curve (BAC) of the surface profile of the tape. To implement the new procedure, an unidirectional strips of carbon fiber/PEEK were laid down on the polished steel tool with different placement rates, compaction forces, hot gas torch (HGT) temperatures, and tool temperatures. The degree of intimate contact is calculated based on the proposed experimental approach and compared with prediction models from the literature. Furthermore, the effect of AFP process parameters on the degree of intimate contact is studied using BAC method and the effective intimate contact model. The results showed that the development of intimate contact is significantly governed by the torch and tool temperature.

Disassembly damage and bearing capacity of shaft with surface micro-texture

ABSTRACT The re-assembly performance of the mating surfaces in interference fit was affected by the disassembly in the previous step due to the serious friction damage. The experimental platform was built to investigate the disassembly damage and bearing capacity of a shaft in an interference fit. The effects of the surface micro-textures with different shapes and densities on disassembly damage and bearing capacity of the shaft in an interference fit were analysed from the micromorphology, microstructure, and material properties. For the micromorphology, the effects were explained based on the bearing area curve. For the microstructure and material properties, the surface strength of micro-textured surface was enhanced due to the fine grain strengthening and dislocation strengthening. The surface hardness was improved due to the generation of martensite. The results showed that the circular micro-textured surface with 20% area density effectively reduced the disassembly damage and increased the bearing capacity of the shaft in an interference fit.

In-situ surface wear assessment using a bearing area curve technique

ABSTRACT Wear during running-in of rolling contact occurs at the surface asperities level and cannot be assessed using a conventional mass loss technique due to the very small changes. The purpose of this paper is to propose an in-situ wear volume measurement using the BAC technique. The experimental work is conducted in-situ and a fixed datum is set as a reference to avoid measurement errors. The wear volume measurement using a proposed BAC technique is in good agreement with the asperities profile-based technique with a small error of 1.67%. The relocation at 90% of BAC is unnecessary as it causes a measurement error of 4.67%. Therefore, the assumption that no change in the asperity valleys beyond 90% of BAC is inaccurate and may lead to error in the wear volume assessment. This study provides a validation of the BAC technique that has been used extensively in wear volume measurement.

Characterization and functional evaluation of surface texture of micro eccentric shaft based on multi-index

Micro eccentric shaft has important application in many high-tech fields because of its small specific gravity, material, and energy saving. The machined surface texture has an indispensable influence on the surface integrity and the final functional capability. However, due to the micro scale and weak rigidity, it is difficult to characterize the surface texture and evaluate the functionality by traditional quantitative parameters. In order to comprehensively realize the surface texture characterization and functional analysis, a mathematical model is established to simulate the surface texture machined with different cutting tools. Then the surface microscopic profile and functional performance of the surface texture are analyzed by amplitude distribution function (ADF) and bearing area curve (BAC), and the surface texture is also evaluated by fractal dimension, which can avoid the negative effects of scale and resolution. Furthermore, power spectrum density (PSD) is utilized to analyze the relationship between the process dynamic state and geometrical specification of the surface texture. The validity of experimental results shown that the microscopic height distribution of surface machined by flat end milling cutter tends to be more random and there are more microscopic geometric features than that of the ball end milling cutter. The machined surface obtained by the flat end milling cutter has better load bearing, wear resistance, and liquid retention capability.

Bearing Area Curve Based Partitioning for the Verification of Theoretical Supplemental Geometry on Additively Manufactured Lattice Structures

Bearing Area Curve Based Partitioning for the Verification of Theoretical Supplemental Geometry on Additively Manufactured Lattice Structures

Simultaneous improvement of microgeometry and surface quality of spur and straight bevel gears by abrasive flow finishing process

This article reports on influence of extrusion pressure, abrasive particle size and volumetric concentration on simultaneous reduction of surface roughness and microgeometry errors of spur and straight bevel gear by abrasive flow finishing (AFF) process. A vertical configured experimental apparatus was developed for two-way AFF and developed fixtures for finishing gears. Experimental investigations were conducted to identify optimum parametric combination, using response surface methodology, based on Box–Behnken design approach. Results revealed that higher values of abrasive particle size and volumetric concentration yield more percentage decrease in surface roughness and microgeometry error. Roughness profile, bearing area curve, microhardness, surface morphology, and wear resistance of the gear having best quality finishing were studied. Surface morphology analysis of the flank regions of the best finished spur and straight bevel gears found them to be smooth and free from cracks and burrs. Reciprocating wear test results revealed higher wear resistance of the AFF finished gears as compared to the unfinished gears. AFF also enhanced microhardness of the finished gears, which would enhance their operating performance and service life. This study shows that AFF is a flexible, economical, productive, easy to operate, and sustainable nontraditional process for precision finishing of gear that can simultaneously improve microgeometry, surface finish, microhardness, surface morphology, wear resistance, and residual stresses of the finished gears. Gear manufacturers and users will be benefited by the outcome of this study. JEL codes: C00, C20

Analysis of the best roughness surface based on the bearing area curve theory

An in-depth study of friction and wear requires analysis of the surface morphologies and contact status of friction pairs in mechanical systems. The bearing area curve is introduced for the calculation of wear, and combined with the concept of repositioning. The application of fast calculation of wear amount and improved three-dimensional characterization of a bearing area curve is achieved by this new method. The best roughness surface is used as the target surface to extract the target bearing area curve. The influence of microtexture parameters on the bearing area curve is studied to determine the optimal microtexture parameters. The test results show that a matching texture surface has a short run-in time and the lowest friction coefficient after stabilization among the surfaces studied herein, and the presence of a texture changes the wear mechanism from the original adhesive wear to abrasive wear and improves the tribological performance. The best texture parameters and laser process parameters are determined, which provide new ideas for the optimal design of surface topography.

Influence of polymer contacting rollers on surface texture finish in the belt grinding process

During the abrasive machining of hard steels by the belt grinding, the finished surface texture is greatly influenced by the pressure between the abrasive belt and the belt ground workpiece; this pressure is the force applied by the contacting roller on the part. Therefore, the contacting roller has an important role and a direct impact on process efficiency. The purpose of this paper is to study and compare the influence of seven different polymer contact rollers on the belt ground surface texture (PS-R, POM C-R, PA 6-R, PPC-R, PPH-R, HDPE-R, and LDPE-R). The surface texture quality is characterized by eight roughness parameters (Ra, Rz, Rp, Rv, Rsk, Rku, Rsm, and Rdq) and five parameters of the bearing area curve (Rpk, Rk, Rvk, Mr1, and Mr2). The experimental test results indicate a better surface texture obtained by polyamide roller PA 6 (hardness = 60 Shore D) compared to that obtained with other rollers of the same hardness or of different hardness. Simultaneously, an optimal average pressure between the abrasive belt and the workpiece allows the removal of chips without fracturing the abrasive grains; this generates a good surface texture.

Application of eco-friendly lubricants in sustainable grinding of die steel

ABSTRACT In recent years, increasing demand for biodegradable lubricants has been observed in precision machining owing to ISO 14000, which draws more attention toward the operator’s health and environmental issues. In this context, vegetable oils are adopted as eco-friendly lubricants in sustainable lubrication techniques such as Small Quantity Lubrication (SQL). The grinding performance and surface integrity of AISI H13 die steel may also be improved via SQL. The present study aims at revealing the best lubricant for work material by comparing the lubricating characteristic of vegetable oils like castor, groundnut, sunflower, and soybean. The lubrication characteristics were studied in terms of force ratio, surface roughness, surface topography, microchip morphology, and wettability. Experiential results revealed that castor oil exhibited superior lubricating performance, including the lowest force ratio and surface roughness (Rɑ : 0.147 µm and Rz : 1.122 mm), and outstanding surface quality. Furthermore, the wide bearing area (BC) curve and a higher BC ratio (81.76%) indicated the development of an excellent antifriction ground surface in the case of castor oil. The spherical and burnt chips were observed at an infeed of 32 µm in the case of soybean oil. The viscosity of the lubricant significantly influenced the wettability. The lower viscous soybean oil promoted better lubricant wettability in the machining zone.

Baseline Specimens of Erosion and Abrasion Studies.

The difficulty in obtaining human teeth that are caries-free that have similar environmental exposure, e.g., diet intake and water fluoridation has lead researchers to opt for bovine teeth as a substitute for erosion studies. Bovine mandibular incisors are readily available at abattoirs and often originate from the same region and are likely to consume similar dietary intake. The bovine teeth for erosion or abrasion studies usually undergo specimen preparation to produce a “flat surface” baseline specimen. Among other terms used to define baseline specimens for erosion and abrasion studies include phrases like “optically flat” and “flat and smooth surface.” However, these terms might have no quantitative value as it does not justify the actual surface characteristics of the prepared flattened surface. In dentistry, roughness average (Ra) is the most commonly used parameter when reporting the roughness of specimens Reporting Ra alone might not be sufficient as it does not provide information regarding the surface texture as there is no distinction between valleys and peaks, nor does it provide information about the core structure of a material unlike the bearing area curve. The incorporation of Ra and BAP values in baseline specimens has the potential in predicting the wear or lubricating potential of these specimens. Furthermore, standardization of baseline specimens by acknowledging its surface roughness values ensures comparability of erosion and abrasion studies as different specimen preparation technique might influence the outcome or results of research.

Roughness and bearing analysis of ZnO nanorods

It is essential to analyze the surfaces of thin films precisely to control the production process and the performance of nano-scale devices. Conventional techniques give limited information about the nano-scale surface morphology. Instead, atomic force microscopy (AFM) provides more accurate results about the surface parameters of nanostructures. Hence, in the current study, two-dimensional (2D) and three-dimensional (3D) morphological properties of zinc oxide (ZnO) nanorods (NRs) were investigated using AFM. ZnO NRs were produced via a hydrothermal method at different growth times and temperatures. The surface texture was also examined by scanning electron microscopy (SEM). The results revealed that the morphological parameters such as diameter, length, and shape of the nanorods could be tuned by changing growth time and temperature. Moreover, we analyzed the most crucial roughness and bearing analysis parameters, which affect the functional properties of ZnO in the surface engineering applications. The average roughness increased from 5.86 nm to 17.30 nm as growth time increased from 2 h to 5 h. The average roughness was obtained as 10.92 nm for the temperature of 90 °C and it reached 41.13 nm for 150 °C. In addition, height distribution and bearing area curves associated with the real contact area were reported. 90% of the area was spread at a depth of 48 nm for the growth time of 2 h while this value was obtained 183 nm for 5 h Addition, 90% of the area was spread at a depth of 88 nm and 457 nm for the temperature of 90 °C and 150 °C, respectively. We believe that our study would be a pioneering perspective on bearing analysis of ZnO nanorods.

A modified approach based on bearing area curve for surface wear characterization

PurposeWear greatly influences the machine lifetime, performance and reliability and its quantification is very important. This paper aims to propose a modified bearing area curve method by combining the theory of the bearing area curve, and the relocation technique to calculate wear accurately and efficiently.Design/methodology/approachH13 steel was chosen as the material of wear pair, and the wear experiments were carried out at 50 N, 60 r/min for 20 min. The surface was measured before and after wear experiments. The relocation was made by comparing the mean lines (planes) of the unworn and worn surface profiles. The calculated results using the proposed method were compared with that of the surface profile method for a two-dimensional surface to validate its accuracy. The method was then applied for a three-dimensional (3D) wear analysis.FindingsThe worn surface shows clearly displacement compared to the unworn surface and implies the importance of including relocation in the bearing area curve method. The results from the proposed method are 98 per cent close to that from the surface profile method, indicating that the method is accurate for wear evaluation.Originality/valueAs no feature point or relocation mark is needed to calculate the relocation value using the proposed method, the method can be applied to mild to severe wear. Also, as the deviation of different scans does not affect the relocation calculation, and no matching and stitching is required, this method can be easily applied to a wide wear area and 3D surface wear analysis.