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

Abstract

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.

Keywords:

• Ceramic microdrilling
• Manufacturing tolerance
• Taguchi's experiment
• Tool wear