Bearing Area Curve Research Articles

Evaluation of surface topography and bearing properties of hard turned surfaces using differently shaped PCBN tools

S u m m a r y This paper deals with hard turning using conventional and wiper polycrystalline cubic boron nitride (PCBN) tools. 3D surface topographies and bearing area curves were determined and compared after hard turning with differently shaped cutting tools. Machined parts were made of a 100Cr6 (AISI 5210) hardened bearing steel with Rockwell hardness HRC=60 ± 1 HRC.

Precision Finishing of Bevel Gears by Electrochemical Honing

This article presents some studies on precision finishing of straight bevel gears using electro-chemical honing (ECH) process. Surface roughness and form errors in terms of pitch and runout error have been studied as process performance measures. An innovative experimental setup has been designed and developed for ECH of bevel gears using a novel concept of twin complementary cathode gears. It ensures finishing of the entire face width of the workpiece gear and the inter-electrode gap required for the ECM action to take place. In this concept, one of the cathode gears has an undercut conducting layer sandwiched between two insulating layers while, in the other cathode gear, an insulating layer is sandwiched between two undercut conducting layers. The results have shown noticeable improvement in the surface finish and form accuracy in an optimized finishing time of 2 minutes. The scanning electron microscope (SEM) images and bearing area curves have also shown improvement in the surface integrity and material contact ratio thus ensuring enhanced tribological performance and maximum service life of the gears. All these results have proven ECH as a viable and productive alternative gear finishing process.

Modeling of material removal rate and surface roughness in finishing of bevel gears by electrochemical honing process

This paper describes mathematical modeling of material removal rate (MRR) and surface roughness of the bevel gears finished by the electro-chemical honing (ECH) process. Since, ECH hybridizes electrochemical dissolution (ECD) and mechanical honing therefore, contribution of ECD in MRR and surface roughness has been modeled using Faraday's law of electrolysis while contribution of mechanical honing has been modeled considering material removal as a phenomenon of uniform wear and using Archard's wear model. Formulations are also proposed for computing the surface area, required by these two models, along the inter-electrode gap (IEG) based on the geometry of the straight bevel gear tooth surfaces. The developed models were experimentally validated using an indigenously developed experimental setup for finishing of bevel gears by ECH based on an envisaged novel concept of twin complementary cathode gears. An aqueous solution containing 25% NaCl+75% NaNO3 was used as the electrolyte. The predicted values of MRR and surface roughness have shown close agreement with the experimental values. The experimental results, SEM images and bearing area curve have shown appreciable improvement in the surface roughness and surface integrity ensuring better operating performance of the gears finished by ECH within an optimized finishing time of 2min.

Verification of a characterization method of the laser-induced selective activation based on industrial lasers

In this article, laser-induced selective activation (LISA) for subsequent autocatalytic copper plating is performed by several types of industrial scale lasers, including a Nd:YAG laser, a UV laser, a fiber laser, a green laser, and a short pulsed laser. Based on analysis of all the laser-machined surfaces, normalized bearing area curves and parameters are used to characterize the surface quantitatively. The range of normalized bearing area curve parameters for plate-able surface is suggested. PBT/PET with 40 % glass fiber was used as the substrate material. For all of the studied lasers, the parameters were varied in a relatively large range, and matrixes of the laser-machined surface were obtained. The topography of those laser-machined surfaces was examined by scanning electronic microscope (SEM). For each sample examined by SEM, there was an identical workpiece plated by for 90 min. The obtained copper thickness was measured. It is confirmed that copper only deposits on the surface that has a porous structure. The bonding strength between the copper layer and the substrate was also measured.

The Behavior of Surface Roughness in EHL Contacts Under Small Slide to Roll Ratios

The amplitude attenuation theory represents a possible way how to predict the tribological performance of a surface having general roughness. There are applications of this theory for pure rolling and rolling–sliding conditions having different governing parameters. Obviously, pure rolling case is much simpler and it was already experimentally verified. Conversely, rolling–sliding conditions represent much complex case and its solution is still under development. Nevertheless, a lot of machine components operate under the conditions where only small slide to roll ratios are present. This study was carried out to find the reasonable validity of the pure rolling model for the applications where small amount of sliding is present. The behavior of roughness was observed under conditions of small sliding speed using optical tribometer for film thickness mapping. The results were analyzed and compared with the predictions according the amplitude attenuation theory for both pure rolling and rolling–sliding cases. The influence of slide to roll ratio on roughness profile shape was studied and differences to the pure rolling profile were evaluated. It was concluded that the pure rolling model can be applied with reasonable precision within the range of slide to roll ratios from −0.15 to 0.1. The correlation coefficients are better than 0.85, the RMS value changes are less than 3 %, and bearing area curves are almost unaffected.

Prediction of Real Contact Area from Microtopography on CMP Pad

A simplified model related to microtopography on CMP pad and prediction of real contact area between the pad and wafers is presented in this paper. The model has been developed on the basis of the analysis of the pad surface roughness and contact mechanics. The bearing area curve, representing tribological properties of the surface, is used to formulate the model. The pad microtopography which is expressed in the model is uniform and simple. Particularly, the important characteristics of the pad microtopography for the CMP process are emphasized in the model. It provides more convenient way to perceive the situation of the pad surface during the CMP process. The progress of the pad surface wear and the real contact area can be easily taken and connected each other by using the model. The model is also verified by comparing the tendency of actual removal rates with those theoretically anticipated. Finally, authors could get the efficient link between the pad surface wear and the real contact area, which results in a strong tool to understand the fundamental CMP mechanism of material removal.

Selective metallization of polymers using laser induced surface activation (LISA)—characterization and optimization of porous surface topography

Laser induced selective activation (LISA) is a molded interconnected devices technique for selective metallization of polymers. On the working piece, only the laser-machined area can be metalized in the subsequent plating. The principle of the technology is introduced. Surface analysis was performed on the laser-machined polymer using an Alicona InfiniteFocus® microscope. Based on previous experiments, bearing area curve and its parameters are chosen to characterize the surface. In this paper, by comparison of plateable and non-plateable surfaces, and two types of plateable surface made by different lasers, it is found that the normalized bearing area curve is an effective method to characterize porous surface for the subsequent plating. The normalized parameters are available to make a quantitative analysis.

Determination of the real contact area for numerical simulation

The knowledge of the real area of contact plays an important role in metal forming processes as it influences friction and heat transfer in the tool–workpiece interface. In accurate finite element analysis, friction and heat transfer have to be faced by numerical interface models that consider the real contact area in dependence of the applied normal load. Up-to-date methods for the calculation of the real contact area–load relation are either oversimplified or too complex to be used in interface models. This paper presents a new method for evaluating the real contact area in dependence of the normal load that takes the material properties and real asperity slopes into consideration, and simplification (compared to e.g. the work of Neumaier [Zur Optimierung der Verfahrensauswahl von Kalt-, Halbwarm- und Warmmassivumformverfahren, Fortschritt-Berichte VDI: Reihe 2, Fertigungstechnik, vol. 637. Düsseldorf: VDI Verlag, 2003] is achieved by making use of the statistical character of real surfaces. The main idea of the new concept is to obtain the real contact area–load relation by combining the bearing area curve and a model asperity with correct representation of the mean asperity slope.

An Investigation on Quenching Performance of Hot Alkaline Bath

Abstract An investigation was done on understanding the cooling affect of alkaline salt bath medium on microstructure, mechanical and surface properties of AISI 1045 steel in comparison with oil. Salt bath medium used in this research contained 40 % NaOH and 60 % KOH with addition of 5 wt. % water at 205°C. H-value of the medium was determined by the Rushman Lamont method. This value was found to be 0.4. Hardening of 1045 steel in salt bath resulted in higher hardness and improved hardenability in comparison with oil quenching. Strength and ductility was also increased by this treatment. This was found to be a direct result of different microstructures evolved during quenching treatments. Hardening of 1045 steel in this medium resulted in an almost uniform microstructure which consisted of fine martensite and bainite. In comparison the microstructure of oil quenched sample was martensite, ferrite, widmanestatten ferrite and pearlite. Surface properties also improved by decrease in surface roughness and a good bearing area curve.

Comparison of Microstructure and Surface Properties of AISI 1045 Steel After Quenching in Hot Alkaline Salt Bath and Oil

The effect of quenching in molten alkaline salt bath medium on the microstructure and surface properties of AISI 1045 steel in comparison with oil was investigated. Salt bath medium used in this research contained 40% NaOH and 60% KOH with addition of 5 wt.% water at 205 °C. Hardening of 1045 steel in this medium resulted in an almost uniform microstructure, which consisted of fine martensite and bainite. In comparison, the microstructure of oil quenched sample was martensite, ferrite, widmanestatten ferrite, and pearlite. Quenching in salt bath lead to improved surface properties, i.e., decrease in surface roughness and a good bearing area curve.

New cylinder liner surfaces for low oil consumption

Anticipated emission legislation and reduced fuel consumption are the main driving forces when developing new engines. Optimization of the active surfaces in the piston system is one possible way to meet the above demands. In this study the effects of surface topography and texture direction of the ring/liner contact on oil film thickness and friction were simulated and experimentally tested. “Low wear” results from the experimental wear tests with “glide honed” smooth liner surfaces supported the “low friction” simulation results. In addition a new wear volume sensitive surface roughness parameter, R ktot, based on the Abbot–Firestone bearing area curve was introduced.

Influence of tool wear on surface roughness in hard turning using differently shaped ceramic tools

Hard turning has been applied in many cases in producing bearings, gears, cams, shafts, axels, and other mechanical components since the early 1980s. Mixed ceramics (aluminum oxide plus TiC or TiCN) is one of the two cutting tool materials (apart from PCBN) widely used for finish machining of hardened steel (HRC 50–65) parts, especially under dry machining conditions and moderate cutting speed ranging from 90 to 120 m/min. This paper reports an extensive characterization of the surface roughness generated during hard turning (HT) operations performed with conventional and wiper ceramic tools at variable feed rate and its changes originated from tool wear. Moreover, it compares some predominant tool wear patterns produced on the two types of ceramic inserts and their influence on the alteration of surface profiles. After the hard turning tests, the relevant changes of surface profiles and surface roughness parameters were successively registered and measured by a stylus profilometer. In this investigation, a set of 2D surface roughness parameters, as well as profile and surface characteristics, such as the amplitude distribution functions, bearing area curves and symmetrical curves of geometrical contact obtained for the machined surface, were determined and analyzed. A novel aspect of this research is that the notch wear progress at the secondary cutting (trailing) edges was found to produce the substantial modifications of the individual irregularities, and constitute the altered surface profiles. Moreover, this research contributes to practical aspects of HT technology due to exploring the relations between the tool state at different times within the tool life and the relevant surface roughness characterization.

Surface finish on hardened bearing steel parts produced by superhard and abrasive tools

New technological process consisting of hard turning (HT) followed by abrasive machining, in place of the widely used method in industry, i.e., hard turning versus grinding, has lately been launched in the automotive industry. This is because, many transmissions parts, such as synchronizing gears, crankshafts and camshafts require superior surface finish along with appropriate fatigue performance. This paper provides a comprehensive characterization of part surface finish produced in dry turning of a hardened AISI 52100 bearing steel using mixed ceramic (MC) and PCBN tools, and also its modification after special abrasive finishing operations including superfinishing (SF) and belt grinding (BG). In this investigation, some important 2D and 3D surface roughness parameters, as well as profile and surface characteristics, such as the amplitude distribution functions, bearing area curves, surface topographies and contour maps obtained for the four surface types selected, were determined and analyzed. Experimental data gained during measurements indicate that each of the finishing abrasive processes provides a specific set of surface topologies. The transformation of bearing properties of surfaces, generated through two optional PCBN HT-BG and MC HT-SF machining sequences, are highlighted. As a result, the modifications of surface profiles achieved by means of special abrasive machining operations can distinctly improve the bearing properties of previously hard turned surfaces, and exemplarily, they shorten the running-in period.

Functional Filtering and Performance Correlation of Plateau Honed Surface Profiles

Plateau honing produces a unique texture on cylinder liner surface. This surface is engineered to simulate the actual running in process of the engine and results in a core layer superimposed on valleys. Because of the complex nature of the surface, characterization of such surfaces is very different from traditional surface texture analysis. Different filtering techniques have been employed to remove waviness from these profiles. Parameters are subsequently computed from the bearing area curve of the roughness profile. With recent progress in filtering of surface profiles, we propose a functional analysis approach based on morphological filters. The advantage of this technique is the clear separation of the core texture from the valleys resulting in better correlation with process and functional measures. A number of profiles are collected from two sets of liners with different performance characteristics. A cause effect model is built and used for performance prediction.

Identification of scratch mechanisms on a retrieved metallic femoral head

The degradation of the femoral head roughness caused by scratching is known to increase the wear rate of the polyethylene counterface of the Charnley total hip prostheses and therefore to have an impact on osteolysis. The knowledge of the scratching mechanism is hence of paramount importance to improve the long-term clinical performance of these prostheses. The aim of this study is to identify the mechanism of scratch generation of a retrieved titanium (TA6V) femoral head through an accurate characterisation of its surface topography. The surface topography features have been assessed both qualitatively and quantitatively by respectively using an optical microscope and a three dimensional contacting profilometer. Based on the scanning of about 80 areas spread over the entire surface of the retrieved femoral head, hypotheses on the mechanism of scratch generation have been formulated after analysing the observed topographical patterns, the arithmetic mean roughness and the amplitude density function (ADF). The formulated hypotheses have finally been verified comparing the ADF and the bearing area curves of profiles related to the most severely scratched areas with those of simulated worn profiles. This study highlights the major influence of foreign third bodies on the scratching of metallic femoral heads of the Charnley type prostheses.

Adsorption State and Morphology of Tetracyanoquinodimethane Deposited from Solution onto the Atomically Smooth Native Oxide Surface of Al(111) Films Studied by X-ray Photoelectron Spectroscopy and Atomic Force Microscopy

The adsorption state and morphology of tetracyanoquinodimethane (TCNQ) deposited from acetonitrile solutions onto atomically smooth native oxide surfaces of Al(111) films were investigated by X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). The analysis of the XP spectra of the deposited TCNQ showed that it is adsorbed as both a neutral and ionized state on the surfaces and the intensity for the former increases more rapidly than that for the latter as the concentration increases. The atomically smooth surfaces of the Al films allowed the detailed observation and analysis of the morphology of the deposited TCNQ. The surface height analysis (bearing analysis) of the AFM images of the deposited TCNQ showed that it is adsorbed as both a uniform film on a nanometer scale and micrometer-sized particles with height ranging from 10 to 100 nm above the surfaces. The volumes of the thin uniform film and the large particles of the deposited TCNQ could be obtained separately from the analysis of the bearing histograms and bearing area curves of the AFM images. A similarity in the dependence of both the volumes of the large and small particles of the deposited TCNQ obtained by AFM and in that of the surface concentrations of neutral and ionized TCNQ obtained by XPS on the concentration of TCNQ in solution clarified the adsorption mechanism. It is concluded that the large particles are identified as microcrystallites of neutral TCNQ and the thin uniform film results predominantly from corrosion of the oxide surface by the TCNQ anion formation reaction.

Fundamentals of Surface Mechanics with Applications, Second Edition. Mechanical Engineering Series

Fundamentals of Surface Mechanics with Applications, Second Edition. Mechanical Engineering Series

Software relocation of 3D surface topography measurements

In a number of 3D surface topography measurements it is both necessary and of great use to relocate exactly the same area, e.g., in the study of wear processes, in correlation studies of slightly overlapping characterisation techniques, and in the study of replica techniques. The objective of the present paper is to evaluate the performance of an automatic relocation process based on a simplex algorithm. The method is implemented in MATLAB™. The cross-correlation coefficient between the topographical data determines the evolution of the relocation process. Two variations of the method are used, i.e., one uses the full range of the input data and the second uses a truncated version of the input data. The truncation is based in selected percentages of the bearing area curve. Four different surfaces and two different techniques are used in this study.

Atomic force microscopy observation of the morphology of tetracyanoquinodimethane (TCNQ) deposited from solution onto the atomically smooth native oxide surface of Al(111) films

The morphology of tetracyanoquinodimethane (TCNQ) and of benzoic acid deposited from solutions onto atomically smooth native oxide surfaces of Al(111) films was observed by atomic force microscopy (AFM). A surface height analysis (bearing analysis) of the AFM images of TCNQ-deposited atomically smooth oxidized Al films gave a bimodal height distribution of the adsorbed TCNQ on the surfaces. The height distribution showed that TCNQ is adsorbed on the oxide surface as both a uniform film on a nanometer scale and micrometer-sized particles with the height ranging from 10 to 100 nm above the surface. The large particles are easily identified by AFM as microcrystallites of neutral TCNQ and they have many morphologies. The uniform film with the nanometer scale height distribution results predominantly from corrosion of the oxide surface by the TCNQ anion formation reaction. The volumes of the large particles and of the thin uniform film were obtained separately from the analysis of the bearing histogram and bearing area curve. Generally, the volume (approx. 2 μm 3 for a 30×30-μm 2 area) of the thin uniform film is 4–5 times larger than the volume of one monolayer of TCNQ or TCNQ salt. Benzoic acid treated surfaces, on the other hand, did not show a bimodal distribution nor large particles, and surface roughness is consistent with monolayer formation of aluminum benzoate. Discrepancies in inelastic electron tunneling spectroscopy and X-ray photoelectron spectroscopy results for TCNQ adsorption on alumina were discussed.

Quantitative Evaluation of Wear Grooves in a Fine Particulate Reinforced, Soft Polymer Coating System by Laser Profilometry and Computer Aided Scratch Analysis

After certain periods of practical application, particulate reinforced polymer coated surfaces frequently contain many grooves due to a scratching contact with any abrasive counterparts. To characterise these scratch patterns a software package (SCRATCH) has been developed using digitised surface roughness data from a laser profilometer. The SCRATCH system identifies individual scratches by representing their locations (using a slicing technique) and specifies scalar parameters (such as the specific scratch area or mid-tangent of the bearing area curve). In this way, the magnitude of the scratch damage can be identified following an approximate technique. This is demonstrated here for wear grooves in a polymer coating system subjected to a particular scratch test. But the method can also be applied to other engineering surfaces, e.g. for wear evaluation of composite bearings, seals and other sliding composite elements.