Grinding Mechanisms and Energy Balance for Ceramics

An investigation is reported of the mechanisms and associated energy for grinding of ceramics. SEM observations of grinding debris indicate material removal mainly by brittle fracture. However, microscopic examination of the ground surfaces reveals extensive ductile flow with characteristic plowed grooves along the grinding direction. From an order of magnitude analysis it is shown that the energy expended by brittle fracture can comprise only a negligible portion of the total. Virtually all of the grinding energy is attributed to ductile flow by plowing. For a number of ceramic materials ground over a wide range of conditions, the grinding power is found to be nearly proportional to the rate o plowed groove area generated, which suggests a constant energy per unit area of plowed surface Js. Values obtained for Js are much bigger than the corresponding fracture surface energies and proportional to Kc3/2H.