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The pin-on-disc dry sliding friction and wear experiments have been made on 42CrMo4 steel in contact with Si3N4, SiC, WC, Al2O3, and ZrO2ceramic balls. The tests were carried out at sliding speeds of 0.16 m/s, 0.24 m/s, and 0.32 m/s. During the tests, the friction force was monitored as a function of time. Discs and balls wear was measured after the tests using a white light interferometer Talysurf CCI Lite and Altisurf 520 optical profilometer with a CL1 confocal probe. To decrease variations in the experimental results, during the tests, wear debris was continuously removed from the disc surfaces. It was found out that with Al2O3counterpart the wear volume of the steel discs was the largest. However, the largest wear volume of the balls was observed for Si3N4ceramic balls.

This paper describes the tribological effect of surface topography on friction and wear under dry fretting regime of a point contact. Experiments were made using SRV4 ball-on-disc tribotester. 100Cr6 sphere of 64 HRC (Rockwell method, scale C) hardness co-acted with a disc made of 42CrMo4 steel with hardness of 40 HRC. Fretting tests were carried out under dry gross slip conditions. The diameter of ball was 10 mm. During tests, normal load was kept constant at P = 50 N within the contact. Duration of each test was 15 min. Tests were performed in 26 ℃ temperature in the chamber at 39–43% of relative humidity. Displacement amplitude was 0.1 mm (stroke was 0.2 mm) with frequency of 20 Hz. The disc samples had different textures obtained after one process (grinding, vapor blasting, or polishing) and two process (grinding or vapor blasting followed by lapping). During tests, the friction force was monitored as a function of time. Wear of disks and balls was measured after the test using white light interferometer. Surface roughness height of discs, determined by the Sq parameter was in the range: 0.01–4.5 µm. It was found that initial surface roughness height had a significant influence on friction and wear in dry gross slip conditions. For rougher disc surfaces, the friction force in initial test stage and wear of co-acting parts were higher.

Wear tests were conducted using a ball-on-disc tester. In the experiment, 42CrMo4 steel disc of hardness 40 HRC was put in contact with 100Cr6 steel ball of 6.35 mm diameter. Hardness of ball was 60 HRC. Disc samples were created using vapor blasting and/or lapping techniques in order to obtain one-process and two-process isotropic surfaces. Dry and lubricated tests were carried out. During tests, the friction force was monitored as a function of time. Wear of discs and balls was measured after the test using white light interferometer. Under dry friction conditions, two batches of tests were performed. In order to decrease variation of the experimental results, during tests the wear debris was continuously removed from the disc surface. Tests under starved lubrication conditions were carried out using L-AN 46 oil. One drop of oil was supplied into the inlet side of the contact zone. It was shown that beneficial effects of two-process surfaces on tribological behavior of sliding pairs depended on the operating conditions.

Wear tests were conducted using a pin-on-disc tester. In the experiment, a steel disc of hardness 40 HRC was put in contact with a steel pin of hardness 64 HRC with spherical end. Disc samples were prepared in order to obtain very similar values of the Sq parameter of one-process and two-process isotropic surfaces. Height of one–process disc surfaces, characterized by the Sq parameter was in the range 0.5 – 6 µm, but of two-process textures 1- 4.5 µm. Dry and lubricated tests, using different contact conditions were carried out. During testing, the friction force was monitored as a function of time. Wear of disc was measured after the test using white light interferometer. Tests under boundary lubrication condition were done using L-AN 46 oil.

The paper presents results of the tests concerning slide bearings having modified journal with helical groove. Such a bearing is more wear-resistant than the classical bearing in case of hard particles presence in oil. Investigations show that above mentioned modification results in over twofold decrease in wear intensity in case of suitable helical groove parameters. Differences in worn journals surface topography for investigated variants have also been stated.

Three methods of simulation of two-process profiles were compared. An idea for the best method is to impose a random Gaussian profile on the valley profile. A special procedure was developed by the present authors to obtain desired values of skewness and correlation length. The extension of this method was used in order to model three-dimensional surface topography after two processes. The imposition method was used for plateau-honed cylinder surface topographies simulation. The mating accuracy of modelled and measured topographies was good, taking into account the complicated character of plateau-honed cylinder surfaces.

Modeling Profiles After Vapour BlastingThe irregularity profiles of steel samples after vapour blasting were measured. A correlation analysis of profile parameters was then carried out. As the result, the following parameters were selected: Pq, Pt, P?q, Pp/Pt and Pku. Surface profiles after vapour blasting were modeled. The modeled surfaces were correctly matched to measured surfaces in 78% of all analyzed cases. The vapour blasting experiment was then carried out using an orthogonal selective research plan. The distance between the nozzle and sample d and the pressure of feed system p were input parameters; selected surface texture coefficients were output parameters. As the result of the experiment, regression equations connecting vapour blasting process parameters p and d with selected profile parameters were obtained. Finally, 2D profiles of steel samples were forecasted for various values of vapour blasting parameters. Proper matching accuracy of modeled to measured profiles was assured in 75% of analyzed cases.

A review of the existing methods describing the cylinder bore surface roughness was presented. An analysis of the surfaces of a large number of honed cylinders was performed. The relationship between conventional and proposed roughness parameters was studied using the principal components method as well as correlation and regression analysis. It follows from the analysis that one can fairly precisely describe a cylinder surface roughness profile using the following parameters: the emptiness coefficient Rp/Rt, the normalized rough core depth Rk/Rt, one of the height parameters (Rtmor R3yare proposed) and the mean distance among deep valleys. A wider description includes also the real oil capacity and one of the horizontal parameters.

The main objective of this work is to model wear of a disc which was subjected to dry contact with a ball in unidirectional sliding. Tribological tests of sliding pairs were carried out using a tribological tester T-11 in a ball-on disc configuration. Stationary balls made of 100Cr6 steel with a hardness of 62 ± 2 HRC co-acted with rotating discs with 42CrMo4 steel with a hardness of 40 ± 2HRC. Discs were machined by lapping, grinding, milling, and vapour blasting. The values of the Sq parameter of disc surfaces were between 0.1 and 5.86 µm. Wear volumes of the discs were lower for bigger roughness heights. The simulation of disc wear was conducted on the basis of the repetitive contact between sliding surfaces. Strong correlation was achieved between the modeled and measured volumetric wear levels.

The effect of the apex angle of triangular oil pockets created on a disc surface on friction was studied. Experiments were carried out using an Optimol SRV5 tribotester equipped with a pin-on-disc module under unidirectional lubricated sliding. Both the sample and counter sample was made of steel of 45 Hardness Rockwell C (HRC) hardness. Only 1 ml of oil was put to the inlet side of the contact area at the beginning of each test. All textured surfaces had the same pit-area ratio and an average depth of dimples. Oil pockets were positioned in the spiral array. It was found that the effect of the apex angle of triangular dimples on friction reduction was important. When the normal load was lower, the smallest coefficient of friction was achieved for the sliding pair with a disc apex angle of 60°. Under a larger normal load, a higher apex angle corresponded to a higher coefficient of friction.