Study to enhance the micro-level in USM

With the wide applications of the hard brittle materials in micro electromechanical system (MEMS), the high precision micromachining technology of hard brittle materials has become an important subject. In order to enhance the machining accuracy and the degree of the micro ultrasonic machining (USM), the key technologies in micro USM are discussed. They include high precision machine body, rotated tool, on-line tool preparation, applying vibration to the workpiece, choosing the parameters of micro tool and so on. The buckling dynamic stability of the micro tool is analyzed. It not only depends on the static pressure but also on the ultrasonic amplitude. The formula for calculating the critical length of the tool is given. It can solve the problem of the tool's bend, breakage, and deteriorating the hole shape accuracy in machining process caused by the improper choice of tool length, static pressure and ultrasonic amplitude. The experiment is carried out on the micro USM system, and the machined samples are presented.