Experimental studies on tool wear in μ-RUM process

Tool wear in micro-manufacturing process is of paramount importance to meet stringent design requirements of workpiece in a cost-effective manner. In present work, tool wear in micro-rotary ultrasonic machining (mu-RUM) has been investigated for 300-mu m peck drilling operation. Two sets of experiments have been conducted using electroplated hollow diamond tool and borosilicate glass as workpiece to evaluate the effects of mu-RUM parameters on tool wear. In the first set, the effects of tool-based parameters like grain size and thickness of hollow tool have been studied using full factorial design and optimum tool design was obtained. In second set, the effects of process-related parameters like spindle speed, distance traverse in each stroke, table feed rate, vibration amplitude, and vibration frequency on tool wear were studied using central rotatable composite design with optimum tool designed in first step. Analysis of variance has been used to study the significance of mu-RUM factors on tool wear(.) After investigation and analysis of the data, it has been concluded that thickness and grain size of hollow diamond tool had an inverse effect on tool wear. Tool with 100-mu m thickness and 30-mu m grain size was best possible tool for minimum tool wear. It has also been found that process parameters like traverse in each stroke, vibration amplitude, vibration frequency, and spindle speed have affected tool wear, but vibration frequency was most influencing process parameter and resulted in rapid tool wear if not selected properly.