PCD coating polishing effect on the tool wear in high-speed milling of graphite

The manufacture of molds with increasingly shorter deadlines and costs requires tool manufacturers to improve their manufacturing processes. One of the ways is improving their electrode machining, because this process will affect directly in the result of the dimensional precision and production time of the mold. The usage of graphite as raw material for electrodes is known to be highly satisfactory since the graphite has the advantage of machining faster and allowing a great variety of geometrical forms; however, its main disadvantage is that the graphite also has a high level of wearing during the machining process. The cutting-edge preparations are used in order to reduce the effects of this problem, increasing the durability of the tools. In that interest, this paper has researched the effect of edge preparations, through the polishing of the PCD coating, on the wear of tools, in milling of graphite electrodes. Therefore, experimental tests were performed with untreated and polished tools, with abrasive brushes, and by drag finishing. The tests consisted in machining electrodes with analysis of tool wear, roughness, and characterization of the tools. The findings indicate that the edge preparation results in modifications on the coating surface, reducing the roughness value by a mean of 23%, and in the case of drag finishing process, a variation of the values reduction, since this process is more reliable and reproducible. With regard to the tools’ wear, gains such as reduction of flank wear and a cutting length increase of up to 63% were noticed, in comparison with the original tools.