Presented at The Design for Manufacturability and Manufacture of Ceramic Components Symposium, American Ceramic Society 96th Annual Meeting April 24-27, 1994, Indianapolis, IN and to appear in Ceramic Transaction: Ceramic Components. 1 ROTARY ULTRASONIC DRILLING AND MILLING OF CERAMICS

An experimental study of the rotary ultrasonic drilling of ceramics is first presented. The influence of different process parameters on the material removal rate for machining of magnesia stabilized zirconia is examined. Then a mechanistic approach to modeling the material removal rate during rotary ultrasonic drilling of ceramics is proposed and applied to predicting the material removal rate for the case of magnesia stabilized zirconia. Finally, a new method to extend rotary ultrasonic drilling process to face milling of ceramics is proposed. The development of the experimental setup is described and preliminary experimental results are presented and discussed. INTRODUCTION Possessing many superior properties, such as high strength at elevated temperatures, resistance to chemical degradation, wear resistance, and low density, advanced ceramics have been expected to find more and more applications in the near future. One of the reasons for hindering market expansion of ceramic materials is due to the high cost of machining with current technology compared to other materials. Of the total production costs for ceramic components, machining can account for 30%--60% and sometimes even up to 90% [1]. Therefore, there is a crucial need for the development of nonconventional machining processes applicable to advanced ceramic materials. Ultrasonic machining (USM) is considered as "probably the most frequently used machining method for advanced ceramics" next to grinding [2]. A schematic illustration of USM is shown in Figure 1. The tool (shaped conversely to the desired hole or cavity) oscillates at high frequency (typically 20 kHz) and is fed into the workpiece by a constant force. An abrasive slurry comprising water and small abrasive particles is supplied between the tool tip and the workpiece. Material removal occurs when the abrasive particles, suspended in the slurry between the tool and workpiece, are struck by the downstroke of the vibrating tool. Ultrasonic machining of ceramics has the following advantages. Both conductive and nonconductive materials can be machined, complex three-dimensional contours can be Presented at The Design for Manufacturability and Manufacture of Ceramic Components Symposium, American Ceramic Society 96th Annual Meeting April 24-27, 1994, Indianapolis, IN and to appear in Ceramic Transaction: Ceramic Components. 2 Vibration Static Force Workpiece Tool Abrasive Slurry Vibration Rotation Constant Force Workpiece Coolant Out Coolant In