Fabrication method of polycrystalline diamond micro-drill using a hybrid process of pulsed laser, EDM and precision grinding

Super-hard tool materials such as polycrystalline diamond (PCD) have become advanced materials for fabricating high-performance micro cutting tool. Due to the limitation of the complex tool structure, the tool dimension and the difficult machining characteristics of PCD material, the efficient precision fabrication of PCD micro-drill is still an urgent problem to be solved. Therefore, a new laser-EDM-grinding hybrid fabrication method is proposed to prepare the PCD micro-drill in this study. Firstly, the diameter reduction machining of micro-drill cylindrical surface is conducted by picosecond pulse laser, and the preform machining of micro-drill flute is realized by EDM. Finally, the precision grinding is used to form the high-quality edge structures of micro-drill. The effects of laser and EDM parameters on the fabrication quality of PCD micro-drill are investigated respectively, and the formation mechanism of tool surface micromorphology under these two fabrication methods is analyzed. The PCD micro-drill with a diameter of 0.4 mm and a cutting edge radius of 1.164 mu m is fabricated with the optimized machining parameters, then the drilling performance of the self-fabricated PCD micro-drill is studied by microhole drilling experiment on monocrystalline silicon materials. The micro-drilling experiment results verify that the self-fabricated PCD micro-drill has obvious advantages in micro-hole processing quality.