The wear of diamond in cutting aluminium‐silicon alloy*

Abstract

SUMMARYBecause of the large variation found in the life of single‐point diamond tools used to machine aluminium‐silicon‐alloy piston skirts, a study of the wear of this type of tool has been carried out. Brief details of the machining process are given, followed by a description of some of the relevant properties of diamond and the theories which have already been proposed for its mechanism of wear. The procedure for the study of both special test tools and tools used in piston production is outlined. Microscopical and other techniques used for tool‐wear examination are described in detail. Different aspects of wear, such as fracture and grooving, are reported, together with suggested explanations for some of the wear phenomena observed. The influence of crystallographic orientation on the shape of the wear region is commented upon and the effect of swarf erosion of sintered metal tool shanks is dealt with. The main part of the study is completed by a description of some of the wear microstructures observed using replica transmission electron microscopy. In the final discussion it is suggested that better inspection of tools by the manufacturers, using optical microscopy techniques, could improve tool life by improvement in the initial quality of tools. It is also suggested that sintered metal shanks should be improved by increasing their resistance to abrasion by swarf. Although crystallographic orientation of the diamond affects the shape of wear, it is thought unlikely that a possible optimum orientation would justify the increased cost to produce it within the close tolerance which would be required. No confirmation of any particular wear mechanism for diamond is made but, if the general process of wear is mechanical, it is thought that the fragments of diamond removed will be of sub‐micro size.