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 morphological texturing of forming tool surfaces has a high potential to reduce friction and tool wear and also has an impact on the surface layers properties of formed material. In order to understand the effect of different types of tool textures, produced by nanosecond fibre laser, on the tribological conditions at the interface tool-formed material and on the integrity of formed part surface layers, the series of experimental investigations have been carried out. The coefficient of friction for different texture parameters (individual feature shape, including the depth profile of the cavities and orientation of the features relative to the material flow) was evaluated via a Ring Test and the surface layers integrity of the formed material (surface roughness and subsurface micro hardness) was also experimentally analysed. The results showed a positive effect of surface texturing on the friction coefficients and the strain hardening of test samples material. Application of surface texture consisting of dimple-like depressions arranged in radial layout contributed to the most significant friction reduction of about 40%. On the other hand, this surface texture contributed to the increase of surface roughness parameters, Ra parameter increased from 0.49 μm to 2.19 μm and the Rz parameter increased from 0.99 μm to 16.79 μm.
In many present applications is requested decreasing of weight of components and increasing of their strength. Often unique properties are required. These properties could be solved by using of composite materials. However, different material properties of matrix and reinforcing material cause issues during machining, such as rapid tool wear and delamination of composite. Therefore there is afford to enhance machining process by different ways to decrease tool wear as well as delamination of composite. This article deals with comparison of conventional milling and ultrasonic assisted milling of glass fibre reinforced polymer (GFRP) composite material by special designed cutting tool.
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