Abstract
This paper describes a case study of the evaluation of the geometry of holes made by rotary ultrasonic machining using ellipsoidal characteristics. The characteristics under consideration are half of the average sum of the distances from the two foci of the ellipse（ half sum of the distance）, roughness of the hole inner surface, the difference between the maximum and minimum of the half sum of the distance, and oblateness. The machining factors are feed speed and rotation speed of the tool, ultrasonic vibration power, and coolant pressure.
In order to clarify the hole making mechanism and develop statistical models of these characteristics incorporating these four machining factors, we first designed two levels of factorial experiment and executed sixteen experimental runs. Next, we analyzed the data by analysis of variance. Then we selected parameters and constructed the statistical models. Finally, we discuss the results and show this approach is better for the evaluation of the geometry of holes than the method based on circles.
