Tool Wear, Hole Characteristics, and Manufacturing Tolerance in Alumina Ceramic Microdrilling Process

Microdrilling is an essential process in the electronics, aviation, and semiconductor industries. Since microdrills have low rigidness and a high aspect ratio, precise drilling parameters are required to prevent tool breakage from excessive thrust force or torque. This study implements thousand-micron grade microdrilling experiments in alumina ceramic to investigate the effects of drilling parameters on hole characteristics. Because ceramic has poor machinability, the holes must be fabricated by peck-drilling at shallow depths and continuous cooling. The drilling parameters analyzed included the spindle revolution speed, drill feed rate, peck-drilling return distance, and centering drill depth. Characteristics of the hole diameter and roundness were measured by a computer numerical control (CNC) image measurement device. The optimal parameters combination was derived by a two-stage Taguchi's experiment. This study also observes tool wear on chisel edge and generalizes manufacturing tolerance to obtain stable quality characteristics. This article presents valuable process data for thousand-micron grade microholes drilled in sintered alumina ceramic.