Some observations on the wear of diamond tools used in piston machining

Abstract

Abstract The two existing theories which explain the wear mechanism of diamond are reviewed. Brief mention is made of the industrial application of diamond, in particular the use of diamond turning tools for Al/Si piston skirt finishing. The considerable variation in tool life span for this application is noted and the terms of reference for the investigation are stated. The technique and procedure of testing and examination of tools is described. After outlining the extent and position of wear, a more detailed description of various aspects is made, which includes the effect of crystal orientation, incidence of fracture and the possible effect of growth layers. The microstructure of observed wear is dealt with, in which an attempt is made to explain some of the phenomena described. Finally, the opinion is expressed that a critical crystal orientation is unlikely to be economically justifiable but that various avoidable macro defects affect tool life. It is also suggested that the type of wear mechanism might be load-dependent but that the general mechanism, if mechanical, involves submicro fragmentation.