Evaluation of tribological properties of laser textured hardened tool steels

Abstract

In this paper the laser surface texturing (LST) technology as one of the methods of tribological properties modifying of mating steel surfaces is analysed. The area density of dimple-like depression along with the dimple diameter are the only main factors which significantly influence the friction coefficient value, therefore the effect of different values of area density of dimples: 6 %, 11 % and 16 % on the contact coefficient of friction was analysed. Surface textures were manufactured on the planar areas of compression platens (90MnCrV8 tool steel) using a pulsed-beam laser. The values of coefficients of friction were obtained via a ring compression test. Test sample compression was realized in lubrication-free and hydrodynamic regime. A significant improvement of tribological properties in contact steel areas was experimentally observed in both friction regimes. The results of experiments showed that by applying of surface texturing with defined shape and dimensions of dimples and lubricating oil at the same time, the coefficient of friction value can be reduced to about of 75%.

The Influence of the Tool Surface Texture on Friction and the Surface Layers Properties of Formed Component

“…For example, a significant improvement of friction behaviour using a surface texture consisting of dimple-like depressions with density of 6 % was observed in lubrication-free regime. In this case, surface texture contributed to friction reduction to about of 47% [17].…”

“…This value is constant for each texture in this experimental research and is equal to 6%, since the lower values are recommended for reduction of friction coefficient [17,25,26]. To manufacture the surface textures on the planar surfaces of compression platens a 5-axis high precision laser micro-machining centre LaserTEC 80 Shape was used.…”

“…A ring compression test in a lubrication-free regime (dry contact) was performed in order to determine the friction coefficient of the contact pairs [17,38]. During this test, a ring-shaped test sample, which is produced of S235JRG1 steel according to EN 10027-1 standard, is axially compressed among the pair of compression platens.…”