Rotary ultrasonic disk grinding

One possible application of ceramics being explored is in the computer hardware industry. Magnetic computer hard disks are commonly manufactured with an aluminum substrate. The computer industry is moving towards ceramic disks which offer a number of advantages such as higher stiffness and higher storage densities. However, the fired ceramic disks can not meet the high requirements of tolerance and parallelism and therefore have to be machined to their final dimensions. This stage is very costly and time-consuming by conventional processes, such as grinding, lapping and polishing.

The extension of rotary ultrasonic machining to Rotary Ultrasonic Grinding of ceramic substrates for computer hard disks has been investigated (Khanna, 1995; Khanna et al., 1995). It implements rotary ultrasonic machining in a novel manner using a specially-designed diamond tool to provide RUG (Rotary Ultrasonic Grinding) of ceramic disk substrates.

Figure 20 is a skeletal schematic of the experimental setup. The workpiece is rotated by the air bearing spindle on which it is mounted. Constant pressure feed is furnished to the setup by means of a hydraulic circuit. The rotation and vibration of the tool are provided by the rotary ultrasonic spindle. The resulting disks are machined faster than with conventional methods, with a high degree of straightness and parallelism and with few defects.

Experiments have been conducted to evaluate the influence of the process parameters on the material removal rate and surface damage at the main effect and two factor interaction level (Khanna, 1995; Khanna et al., 1995).