Andrzej Dzierwa

Comparison of tribological behaviors of one-process and two-process steel surfaces in ball-on-disc tests

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.

The effect of random surface topography height on fretting in dry gross slip conditions

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.

The Study of the Tribological Properties of One-Process and Two-Process Textures after Vapour Blasting and Lapping Using Pin-on-Disc Tests

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.

Variability of areal surface topography parameters due to the change in surface orientation to measurement direction

Several random surface topographies were analyzed. They were measured by optical (Talysurf CCI Lite) method. They represent one- and two-process anisotropic and isotropic surfaces. These surfaces were rotated of ± 1° and ± 2° by two methods: on the plane table (before measurement) and virtually (after measurement) using the software TalyMap Gold. After each measurement or surface rotation, each surface was levelled. Then, the forms were removed using polynomial of the 3rd degree. Areal surface topography parameters from standard ISO 25178 were calculated. The relative deviations of parameters were determined. The tendency of surface topography changes characteristic to various surface types were analyzed. It was found that change in orientation to the measurement direction of both isotropic and anisotropic surfaces could be substantial source of the measurement uncertainty. Functional parameter Smr and also feature parameters Sda, Sha, Sdv, Shv, and Spd are the mostly sensitive on measurement orientation. Statistical amplitude parameters Sa and Sq are more stable than parameters describing maximum surface height, like Sz, Sp, and Sv. The effect of surface orientation to measurement direction on values of functional parameters from V group was small. It was shown that changes of Sdq, Sdr, and Spc parameters describing hybrid properties due to surface rotation before measurement were smaller than those caused by change in surface orientation after measurement.

Problems of surface topography with oil pockets analysis

The present paper presents method of description of two-process surfaces of random (load-bearing plateau structure) and deterministic (oil pockets) character on the basis of the probabilistic approach of material ratio curve. Examples of this method usage for textured surfaces are shown. The other application of material ratio curve for estimation of pit-area ratio of textured surfaces is discussed. Distortion of surface topography with oil pockets measurement by improper selection of areal reference plane is taken into consideration.

The effect of selected parameters of the honing process on cylinder liner surface topography

Many truck cylinder liners made from gray cast iron were machined. Ceramic and diamond honing stones were used in the last stages of operation: coarse honing and plateau honing. The effect of honing parameters on the cylinder liner surface topography was studied. Selected surface topography parameters were response variables. It was found that parameters from the Sq group were sensitive to honing parameter change. When plateau honing time varied, the Smq parameter increased, while the other parameters, Spq and Svq, were stable.

Simulation of Profiles of Normal Ordinate Distribution

The paper presents the review of various methods of isotropic and anisotropic random surfaces of Gaussian ordinate distribution modeling. The procedure of digital simulation of one-process profile using AR methods of various degrees is presented. We analysed also FFT methods of generating random surface profiles of Gaussian ordinate distribution. The examples of using methods mentioned above for the simulation of machined profiles are given.

Surface Topography of Chromium Coatings after Pneumatic Ball Peening

The paper presents the results of measurements of surface topographies of chromium coatings after pneumatic ball peening. The studies were conducted on steel samples. Four pneumatic ball peening parameters were changed: ball diameter, shot peening pressure, distance between nozzle and workpiece and time of machining. The changes of 3D surface parameters were analysed. The correlation analysis was applied in order to obtain minimum number of parameters describing shot peened surface. Connection between fatigue strength and selected surface topography parameters was investigated.

Influence of Steel Surface Preparation Method on Topography and Tribological Behaviour in Dry Sliding Conditions

Tribological 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 ball of hardness 62 HRC. Disc samples were prepared in order to obtain very similar values of the Sa parameter, smaller than 0.5 μm. Different methods of preparing smooth surfaces were used. Dry tests using similar contact conditions 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. In order to decrease variation of the experimental results, during tests the wear debris was continuously removed from the disc surface. It was shown that type of treatment play a role on tribological behavior of sliding pairs.

The Analysis of Abrasive Wear of the Helical Grooved Journal Bearing

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.