Polishing of uncoated cutting tool surfaces for extended tool life in turning of Ti-6Al-4V

In turning and milling of Ti-6Al-4V, it has been demonstrated that cutting tool insert surfaces processed by magnetic abrasive finishing (MAF) have improved tribological properties and reduced friction at the chip-tool interface, which results in extended tool life. Although a previous study showed the extended life of MAF-processed cutting tool inserts, the mechanism reducing the friction between the chip and the MAF-processed tool remained unclear. This made it difficult to optimize the MAF process for the insert surfaces. This study uses turning of Ti-6Al-4V to clarify which insert faces need to be finished, the desired surface topography, and the finishing conditions required to obtain extended tool lives. It is found that finishing the rake has the most significant effect on the tool life. Furthermore, slight removal of irregular peaks on the as-received rake is more effective than finely smoothing the rake. This reduces the time needed for finishing the tool; the time needed for slight removal of surface peaks from rake requires one thirtieth of the time reported previously for fine smoothing of all faces (rake, flank, and nose). Scalability of the MAF process of rake is facilitated by simultaneously processing multiple cutting tool inserts, which is also demonstrated in this paper.