A study on the failure mechanism and wear loss of impregnated diamond bits during machining process of armor ceramics

Abstract

Thin-wall diamond core bits are usually recommended for the machining of relatively high-sized holes in engineering ceramics. However, during the machining process of engineering ceramics, the tools are usually considerably worn. In this work, the failure mechanism and wear loss of thin-wall impregnated diamond bits has been investigated experimentally during the machining process of Al2O3 armor engineering ceramics. In summary, the failure reasons of the bits can be divided into three cases: Bit skidding, twisted fracture of the bit clamp holder and breakup of the sintering body. The overall wear process of the bits can be roughly divided into three stages: The rapid wear, the stable wear and the sharp wear. The machining duration per hole presents an approximately periodic variation with the number of cumulatively machined holes. Under the experimental conditions, both the bit wear rate and the drilling rate present an approximately periodic variation with the cumulative drilling depth, whereas the corresponding periodic characteristics are not the same. During the hole-machining process, the wear loss of the sintering diamond bits is mainly concentrated on the matrix crown of the bits, but the wear of the matrix binder and the diamond grits on the outer cylindrical surface of the sintering body is negligible.