Effect of laser surface modification on the micro-abrasive wear resistance of coated cemented carbide tools

The use of surface texturing on the rake face of a tool can modify the tribological phenomena present at the chip-tool interface. Many different wear mechanisms, including abrasive wear, occur at the tool during machining. The presence of hard phases in the workpiece material, as well as hard particles removed from the tool, can generate abrasive wear on the tool surfaces. The objective of this work is to study the abrasive wear resistance of micro-textured tools in comparison to conventional (commercial) cutting tools. Square cemented carbide inserts containing a three-layered coating (TiCN-Al2O3-TiN) were textured using two different linear patterns, perpendicular and parallel to the direction of the chip movement. Microabrasion and machining tests on both textured and commercial tools were carried out. Turning tests were carried out for ABNT/AISI 1050 steel under severe cutting conditions with overhead application of cutting fluid. In order to simulate the abrasive wear mechanism that can occur on the tool surface, a free ball microabrasion test was used under a suspension of silicon carbide particles and distilled water. The abrasive wear mechanisms were observed using SEM. The micro-scale abrasive wear resistance of laser micro-textured cement carbide tools was compared to untextured tools. For the turning tests, texturing increased the tool life, which was determined when the wear at the tool flank achieved a specified value. On the other hand, for the microabrasion tests, laser texturing resulted in a pronounced increase in the coating wear rate. This fact was connected to the decrease of coating hardness caused by laser texturing. Therefore, the increase of tool life in the turning tests was not related to a reduction of abrasive wear on the tool flank. Probably, it was caused by other tribological conditions that were not represented in microabrasion tests, for example: the presence of cutting fluid in the environment and elevated contact temperatures.