Micro drilling of hard-to-cut materials: An experimental analysis

The introduction of machine tools specifically designed and industrialised for micro cutting processes, the development of high performance micro tools, and the possibility of easily realising complex shaped surfaces have increased the competitiveness and the industrial interest on these processes. Consequently, many researchers are studying the phenomena involved in the mechanics of micro cutting processes. This paper is focused on the micro drilling process for difficult to cut materials. An experimental analysis, consisting tool life tests, was performed with the aim of highlighting limits and advantages of this cutting process. Three hard-to-cut alloys, namely AISI 310H stainless steel, Hastelloy C22 and Inconel 625 nickel based alloys, were tested. By using standard micro drills, holes 500 μm diameter with two different depths were realised by utilising peck drilling strategy. The final results showed that, differently from macro scale cutting, the workability of hard-to-cut materials at micro scale is mainly affected by the material ductility rather than its hardness.