Investigation of surface characteristics of mirror-finished surfaces using polycrystalline sintered diamond ball end mill

surface roughness known as mirror finishing surface. However, achieving this level of finish on mold cavities with miniature sizes is extremely difficult. To solve this problem, the authors developed a PCD ball end mill that is capable of mirror-finishing hardened steels. This makes it possible to efficiently perform everything from mold cavity cutting to mirror finishing on a single CNC machining center. In this study, we investigated the machining characteristics of mirror-finished surfaces using the PCD ball end mill. Specifically, we investigated the mirror surface level, surface roughness, surface hardness, and crystal structure directly beneath the machined surface for two types of hardened stainless steel. As a result, it was revealed that the surface roughness was within 15nmRa, the crystal structure became finer, and the surface hardness improved to about 100-150HV, on the surface machined by the PCD ball end mill. To summarize the above, it was found that the mirror finishing method using the PCD ball end mill enables efficient mirror finishing and that the finished surface has added value such as improved surface hardness.