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The aim of this investigation is the development of a mathematical tool for predicting the wear behaviour of vane pumps used in the standard method for indicating the wear characteristics of hydraulic fluids according to ASTM D 2882/DIN 51 389.The derivation of the corresponding mathematical algorithm is based on the description of the combined abrasive and adhesive wear phenomena occurring on the...
Surface roughness of metal counterface is an important parameter in the wear process of acetal-metal gear pairs. The topic of this paper is whether the results obtained from pin-on-disc or pad-on-disc machines are valid in real operating conditions, i.e. in the machine itself. For this purpose the wear of acetal-metal gear pairs at different counterface roughnesses in a real device was studied. It...
Significant progress has been made in the past ten years on deterministic modeling and analysis of lubricated rough contacts operating in the regime of micro-elastohydrodynamic lubrication (EHL). This progress has opened new avenues for analytical-computational studies of tribe-contacts that operate in the mixed regime of micro-EHL and boundary lubrication. Work to this date suggests that deterministic...
Tests of dry wear on an Amsler tribometer have been proved on an AISI 9840 steel previously submitted to a quenching and tempering treatment at two different temperatures, as to obtain a material with the same structure but different hardness.The aim of this work is the study of the influence of some factors which characterize material surface state, and more precisely, the hardness, the roughness...
Grit-blasting is commonly used for preparing surfaces for spraying plasma coatings. However, pretreatment by grit-blasting is performed in an empirical and qualitative manner which is often inadequate in the context of modem manufacturing. This paper describes how grit-blasting can be monitored on-line using roughness parameters to specify the surface finish required. The mechanics of grit-blasting...
Pin-on-disc tests of tungsten carbide pins against silicon carbide discs were performed and wear rate, mechanism and friction maps constructed. Correlations were observed between the wear mode and the friction of the pin-disc interface, and between the qualitative incidence of disruptive wear mechanisms and the wear rate. A microploughing wear mechanism was most prevalent at low test loads, but co-existing...
Pin surfaces were analysed by laser profilometry. Two roughness parameters, R a and the fractal dimension, were investigated as a first step towards methods of quantitative wear mechanism mapping. Both parameters were analysed for their relationship to the severity and prevalence of a mechanism. Three-dimensional maps of R a , fractal dimension, average slope and average inter-deviation...
The purpose of this report is to develop the new bonding resin for fixing 3-41 μm SiC abrasives in grinding stone that generates the ultra precision surface on high-purity aluminium alloy. An aluminium disk substrate is processed by a double-sided lapping machine on which the grinding stone is mounted. The developed grinding stone is a resin bond type, composed of a mixture of PVA resin, melamine...
A stochastic finite element model of a one-dimensional hydrodynamic bearing with rough surfaces (longitudinal and transverse roughnesses), considering film thickness to be a stochastic variable, has been formulated and steady-state characteristics studied. The results expressed as mean values of load carrying capacity, flow rate, frictional force and coefficient of friction (in non-dimensional form)...
A sheet-metal forming simulator which stretches a strip around a cylindrical pin was used to investigate the relationship between friction and process variables including sliding speed, strip strain, and strain rate in the boundary lubrication regime. Measurements were conducted with 3104 aluminum alloy sheet of three different surface conditions on D2 tool steel and cemented carbide tooling. Friction...
Surface conformity was characterized in an earlier study on the basis of composite roughness profile. In this paper the influence of surface conformity in lubrication is reported. The results of experiments under high slide/roll ratios are first analysed in terms of Λ, the ratio of film thickness to composite roughness. Experiments with surfaces having different degrees of conformity under low slide/roll...
Traditionally in partial elastohydrodynamic lubrication (EHL), the contact through lubricating films has been modeled assuming random contact and taking into account ratio of film thickness to r.m.s. roughness (h/σ). In some tribological situations the wear process can generate matching at asperity level. In a case such as asperity level conformity the assessment of contact is different from that...
An optical full field method for automatic determination of roughness parameters was elaborated. An experimental set-up for registration of interference fringes, which are consecutive profilograms in direction perpendicular to the lay was presented. The set of profilograms registered by CCD (charge-coupled device) camera is the source data for algorithms calculating two and three-dimensional roughness...
Burnishing is a cold working process, which easily produces a smooth and work-hardened surface by plastic deformation of surface irregularities. In the present work, the influence of the main burnishing parameters (speed, feed, force, number of tool passes, and ball diameter) on the surface roughness and the hardness of two different non-ferrous metals were studied. Furthermore, subsurface hardness...
A three-dimensional elastic contact algorithm has been developed to analyse the normal contact problems of bodies having rough surfaces. The algorithm can evaluate the real contact areas and contact pressure distributions using measured surface roughness data.Following an approximate elastic-plastic contact solution the analysis produces more realistic elastic and plastic contact areas; in addition...
Numerical contact and stiction models are used to study the effect of surface roughness and lubricant film thickness on asperity contact and stiction at magnetic head slider/disk interface (HDI). Isotropic Gaussian surfaces having expected values of the r.m.s. roughness R q and the correlation length β * are generated by computer for the contact and stiction analyses. The analysis...
Ni-P coated Al-Mg (Ni-P) and glass-ceramic (GC) substrates for magnetic recording are measured by an atomic force microscope (AFM) using different scan sizes and sampling resolution. AFM measurements of the Ni-P and GC surfaces reveal finer and finer details as the sampling interval decreases and that the GC surface contains more high frequency details than the Ni-P surface. A three-dimensional numerical...
Although the wear of ultrahigh molecular weight polyethylene (UHMWPE) total joint implant components has received much attention, the creep of this polymer has been inadequately studied. The objectives of this study were to determine whether creep affects the wear of UHMWPE and, if so, to measure the magnitude of this effect. Cylindrical specimens were machined from GUR 4150HP extruded unirradiated...
In tribology it has become common knowledge that surface roughness plays a part in boundary lubrication and mixed lubrication systems. There have been different ways of explaining friction and wear in the contact area. Some claim that the main factor is adhesion between the interacting surfaces, while others maintain that wear particles entrapped at the interface are the predominant factor. In both...
Different approaches toward contact recording are reviewed from the point of view of tribology and their placement on the Stribeck diagram. The various approaches are evaluated critically, and the most practical implementations of these approaches are discussed. It is concluded that a partial air bearing/partial contact approach is the most feasible implementation to succeed.
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