The present publication presents an analysis of the impact of surface stereometry and the absorption coating on the efficiency of ablative laser texturing of 100CrMnSi6-4 bearing steel. Using different variants of surface development and an absorbent resulted, under the same process conditions, in micro-trays differing from each other in geometrical structure (diameter, depth). In the experimental studies, a pulsed Yb:YAG laser with λ = 1.07 µm and a maximum power of 30 W was used. The diameter of the laser beam ranged between 15 and 60 µm, the repetition frequency was 20 kHz and the laser radiation exposure time ranged between 0.5 and 100ns. In the zone adjacent to the trays, fine crystalline martensitic, martensitic-bainitic and bainitic microstructures were found. These microstructures formed as a result of ultrafast phase transformations occurring, among others, during the crystallization of the alloy Fe-C-Cr-Mn-Si liquid phase and the very fast heating and cooling of the surface layer of steel in the solid state. Use of the absorption coating and developing the exposed steel surfaces improve the absorptivity of the laser radiation. With the increase of surface roughness, the efficiency of the laser texturing process was also increased. The results from these tests are promising and may be used, among others, in the production processes of roller bearings, such as in the ablative surface texturing of treadmill roller bearings.
Lasers are widely used in a variety of manufacturing processes including: depaneling, drilling, cutting, repair, trimming, micromachining. Polypropylene foils are intensively investigated as materials with great number of potential applications. Laser cutting is a major operation used in forming these materials and preparing the final workpieces. At the moment, the main challenge when cutting polypropylene is to obtain high quality products characterized by optimum sheared edge condition, minimum surface damage, freedom from burrs, slivers, edge wave, distortion, residual stresses and to obtain minimum width of HAZ zone. The amount of adjusTab. process parameters and the fact that the influence of these parameters on the process is not fully understood makes it difficult to control the cutting process. In practice, the right setup for the lasers is mostly found by trial and error combined with experience. Therefore, the final product frequently has serious defects. The paper presents the possibility of using fiber and diode lasers for forming of workpieces from polypropylene multilayer foil using cutting technology. The effect of selected process parameters and conditions on quality of sheared edge and material degradation is discussed.
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