Wear behavior of different coated tools in MQL-assisted milling of magnesium-based rare-earth alloys

One of the most important and often employed indicators for describing machinability and machining quality is tool wear. While flank wear is commonly used to gauge the extent of a worn scar, tool wear is characterized more by its shape than its size. To quantify the wear shape, more specific data concerning the wear contour is required. With this aim, the present work addresses the fundamental wear mechanisms and failure modes of several coated tools used in the mechanical milling of rare-earth magnesium (Mg-RE) alloys. Uncoated, edge-strengthened, TiAlN-coated, and diamond-coated tools were tested under dry and minimal quantity lubrication (MQL) conditions. The cutting energy flow and consumption rules governing the tool wear processes were quantified using the exergy analysis theory. The results indicate that the cutting performances of tools and the surface quality are both enhanced by the MQL through reducing adhesion wear. For the unstrengthened tool, a tool wear reduction of 55% is achieved by the MQL. While for the TiAlN-coated tool, the tool wear can be furtherly suppressed by 49%.