Formation of Holes in Engineering Ceramic Plates by Press-Working

Abstract

The purpose of the present research is to establish a simple method of forming holes in brittle materials by a conventional press-working. By utilizing a specially designed blunted spherical punch, a small hole is formed at the center of the specimen at its first stage, and subsequently the hole is enlarged by a continuous punching operation. The present improved technique realizes a very low load for punching operation as well as a considerably low clamping stress for preventing serious radial cracks around the hole. Some punching works in engineering ceramic plates were performed by the method for various aspect ratios AR=3∼32(AR=D/t, D; the diameter of the hole and t; the plate thickness). As long as the AR value is larger than about 3, the present method proved to be very successful in forming holes in tough engineering ceramics such as alumina, silicon-nitride and toughend zirconia, as well as in making small holes less than 1 mm in diameter. The technique is also successful in forming many holes by a single operation.