Research on dry micro-milling performance and tool wear of EDM-fabricated polycrystalline diamond micro-end mill
摘要
Sapphire, known for its high hardness and excellent optical properties, is widely used in fields such as aerospace, optoelectronics and defense. Micro-milling technology for sapphire demonstrates significant potential in the field of sapphire surface processing due to its efficiency, high quality, low loss and flexibility. In this study, a double-edged helical polycrystalline diamond (PCD) micro-end mill with a diameter of 1 mm is designed and fabricated by electrical discharge machining (EDM). Then, the micro-slots on sapphire material are prepared with EDM-fabricated micro-end mills, and the surface quality, surface morphology, micro-milling forces and tool wear involved in micro-milling process are investigated. Experimental results indicate that three types of damages are observed on sapphire micro-slot surface including wavy cracks, individual small cracks and layered tear structures. The minimum surface roughness Sa for sapphire micro-slot obtained with PCD micro-end mill can reach to 0.73 µm. In addition, the major wear forms of PCD micro-end mill when machining sapphire include mechanical wear, thermal chemical wear, adhesive wear, and micro-chipping. The research of adopting PCD micro-end mills for sapphire holds significant application value, which can advance technological progress in machining efficiency and surface quality of hard brittle material.