Tribo-mechanical and surface morphological comparison of untextured, mechanical micro-textured (MμT), and coated-MμT cutting tools during machining

Abstract

In machining process, cutting fluids are used to reduce the tool–chip interface temperature and forces, but it causes various health hazards to machine operators as well as increases the associated costs. To improve machining sustainability, researchers are trying to reduce or eliminate cutting fluid usage during machining by various other techniques (development of better tool material, bio-cutting fluids, use of vegetable oils, near-dry machining, process optimization, surface coatings, etc). In recent years, several researchers applied controlled surface modification (surface texturing/engineering) at the tool–chip interface to improve the tribological properties in the machining performance. In the present study, first mechanical microtextures (MµT) are created on the rake surface, and its structural stability is compared with an untextured/virgin cutting tool. The static structural analyses show a negligible effect of mechanical microtextures on the strength of the cutting tool. Afterwards, MµT cutting tools are coated using molybdenum disulphide (MoS2) solid lubricant (i.e. coated MµT, C-MµT). Subsequently, the machining performance studies of C-MµT were carried out to show its advantages over two other types of cutting tools (UC, MµT). Performance of C-MµT is improved by mechanical microtextures (due to the reduction in the actual contact area between tool–chip interfaces) and proper lubrication of the tool–chip contact area. Thus, due to the reduced contact area and formation of lubricant layer by MoS2 at the tool–chip interface, C-MµT experiences 23.75% lower tool–chip interface temperature, 41.06% reduction in the cutting force, and produces 14.37% less workpiece center line average surface roughness ( Ra) compared to untextured cutting tool. C-MµT experiences 9.55% lower tool–chip interface temperature, 19.02% reduction in the cutting force, and produces 5.34% less workpiece center line average surface roughness compared to the MµT cutting tool. Hence, C-MµT cutting tools are the viable alternative to untextured cutting tools.