Wear of diamond wheels in creep-feed grinding of ceramic materials .2. Effects on process responses and strength

Alumina specimens were ground with a resin bonded diamond wheel using three different work speeds in creep-feed up-cut mode. For each work speed, the wheel surfaces and the process responses were evaluated at five different wear states, which were generated by grinding 0, 29.6, 59.2, 88.8, and 118.4 cm(3) volume of a selected silicon nitride material. The mechanisms of wheel wear have been studied and reported in Part I (Wear 211 (1997) 94-103). This paper investigates the effects of wheel wear on process responses and ground ceramic quality, particularly the flexural strength. Strong relationships between the wheel surface conditions and the process responses are found. During the initial stage of wheel wear (from the as-dressed state to the first 29.6 cm(3) volume of material removal), the surface density of diamond grits, surface roughness and flexural strength decreased, and the specific normal force, specific tangential force, force ratio, and specific energy increased. The largest change in most of process responses, except the roughness, occurs at the lowest work speed. Right after grinding 29.6 cm(3) volume of silicon nitride material, process responses stayed approximately the same with some degree of expected fluctuation due to the competing influence of attritious wear and the wheel's self-sharpening effect. The effect of wheel wear on the flexural strength of ground alumina specimens is found to be dominated by the effect of work speed. (C) 1997 Elsevier Science S.A.