Micromechanics of diamond composite tools during grinding of glass

Precision optical components are now manufactured by CNC (computer numerica lly controlled) grinding technology using diamond composite tools. Tooling performance, and in particular consistency of performance, is an important issue in this automation. A key measure of performance is the power/forces required for material removal, often summarized in terms of the specific gr inding energy or 'Preston's coefficient'. In this study measurements of gri nding energy were used, along with optical profilometry measurements of too l surface features, to quantitatively characterize the performance and deve lopment of a bronze-bond composite diamond tool during grinding of three op tical glasses with distinctly different grinding behavior. Evolution of gri nding performance is strongly related to both the process conditions and th e glass type. These effects can be understood in terms of changes in the re lative rates of bond and abrasive wear and the consequent evolution of the tool surface. In particular in certain cases the evolution of tool surfaces can be adjusted toward a state of dynamic equilibrium ('selfsharpening') b y adjusting process conditions. (C) 2000 Elsevier Science S.A. All rights r eserved.