TABLE OF CONTENTS In the previous two chapters, grinding temperatures were analyzed by considering the grinding zone as a heat source which moves along the workpiece surface. Temperatures calculated for given operating parameters were generally found to be proportional to the rate of energy expended and to the fraction of that energy which is transported as heat to the workpiece at the grinding zone (energy partition). For regular shallow cut grinding with conventional abrasive wheels, it was seen in Chapter 6 that heat transfer to the workpiece is especially important, as the energy partition typically ranges from 60 to 90%. High temperatures are generated which may cause thermal damage to the workpiece. This is in sharp contrast to the situation for creep-feed grinding using aluminum oxide wheels as described in Chapter 7. In the absence of fluid burnout, the energy partition for creep feed grinding is typically only 3 to 6%. Thermal damage should not occur if the temperature remains below the burnout limit of the fluid.
The present chapter is concerned with the thermal aspects of grinding with cubic boron nitride (CBN) superabrasive wheels. As compared with conventional aluminum oxide wheels, thermal damage with CBN is generally found to be much less of a problem [2]. For grinding of steels with CBN wheels, workpiece burn is much less likely to occur, and residual stresses at the ground surface are usually found to be predominantly compressive. These observations are indicative of much lower temperatures with CBN than with aluminum oxide wheels.
