With the acceleration of the miniaturization of products, especially in recent years, machining technologies for these products is in need of improvement. Conventional technologies have limitations in realizing the miniaturization due to the downsizing effects of the tools, which lack sufficient cutting stiffness during machining. The application of ultrasonic vibration is one of the most useful solutions in dealing with the problem. This study focused on the difference of ultrasonic drilling from conventional one in geometrical machining mechanism and the corresponding machining results. In detailed, some mathematical equations for drill cutting edge paths during drilling were extracted and new method to find uncut chip thickness from above equations was suggested. The experiments were carried out through the comparison between the results (disposed chips and internal surface states of holes) of conventional drilling and those of ultrasonic drilling. It was determined that the geometrical paths of cutting edges and analyzed uncut chip thickness agree with the appearance of disposed chips. Furthermore, the change in tool path by ultrasonic vibration resulted in the improvement of surface statement.
