Effects of WC grain size and Co content on microscale wear behavior of micro end mills in aluminum alloy 7075 machining

The effects of cemented carbide materials on cutting edge fracture mechanism of micro end mills in aluminum alloy 7075 machining are investigated. A series of micro milling experiments on the tool wear were conducted. The surface morphologies of micro end mills were observed, and the end teeth flank wear length and tool total cutting edge length reduction were measured. The results showed that the Co content and WC grain size of cemented carbides have significant effects on tool wear and cutting performance of the micro end mill. With increase of WC grain size, the tool end teeth flank wear length increases and the total cutting edge length reduction of the mill obviously increases. Thus, the micro end mill with finer grain size presents better wear resistance. However, with increase of Co content, the micro end mill exhibits less wear resistance. This can be explained that the adsorption energy between Co atom and Al atom become larger based on first principle calculation of adsorption energy between cemented carbides and aluminum alloy. The Co binder of tool material is dragged off by frequent fall off of built-up edge, resulting in more loss of Co element. Thus, the strength of the tool is decreased.