Rotary ultrasonic face milling of ceramics

The limitation of rotary ultrasonic machining is that only circular holes can be machined due to the rotary motion of the tool. Attempts have been made to extend rotary ultrasonic machining to machining flat surfaces or milling slots.

Markov et al. (1977) reported the results of their research in machining of deep holes and slots by using a rotating metal-bond diamond tool with ultrasonic vibration. The detailed description of the milling process (machining of slots) was not given. From the drawing of the diamond tool for ultrasonic machining of slots, it can be seen that the direction of oscillation is perpendicular to the feed direction. Tyrrell (1970a) also reported that slotting could be achieved with diamond wheels when the wall of the diamond wheels would be the cutting surface. This method was described as "surface grinding" by Suzuki et al. (1988). Scheme I in Figure 19 illustrates this approach. In this scheme, it was not the abrasives on the tool bottom but the abrasives on the cylindrical face of the tool that undertook the machining. For the abrasives on the cylindrical face of the tool, the cutting mechanism was abrasion. Two other primary mechanisms in rotary ultrasonic machining, namely, hammering and extraction (Prabhakar, 1992), were lost.

Tyrrell (1970a) mentioned that surface grinding could be accomplished with diamond wheels when the tool bottom would be the cutting surface (Scheme II in Figure 19). The drawback of this method was that only those surfaces could be machined which were smaller than the bottom surface of the tool.

Another approach to extend rotary ultrasonic machining to face milling was proposed by Pei et al. (1995c), see Scheme III in Figure 19. In this approach, the cutting surface is neither the cylindrical surface nor the bottom surface, but a conic surface. The advantages of this approach are: (i) none of the three primary mechanisms of rotary ultrasonic machining is lost; (ii) flat surfaces on large workpieces can be machined; (iii) the approach is easy to implement on commercially available machine tools by incorporating some modifications.