Surface integrity in electro-discharge machining, ultrasonic machining, and diamond saw cutting of ceramic composites

Good surface integrity is frequently required for structural ceramic components, since the lifetime of a ceramic component is in most cases determined by its surface features. In this study, the surface integrity of electro-discharge machined, ultrasonic machined, and diamond saw cut ceramic composites has been investigated and compared. The surface roughness, hardness, and topography of the machined surface were examined. Flexural strength and its distributions were used to evaluate the effect of machining process on the surface integrity of the machined specimens. Results show that the machining process had an important effect on the surface quality of the machined ceramics. Electro-discharge machining of ceramics created a heat-affected surface layer with poor surface integrity, such as cracks and craters, and the variable surface damages on the electro-discharge machined specimens resulted in low Weibull modulus. Within most machining conditions, the ultrasonic machined and diamond saw cut specimens behaved fairly consistently, and the flexural strength and Weibull modulus were higher than that of the electro-discharge machined specimens. (C) 2000 Elsevier Science Ltd and Techna S.r.l. All rights reserved.