Thermal and technological aspects of double face grinding of Al2O3 ceramic materials

Double face grinding with planetary kinematics is a process to manufacture workpieces with plan parallel functional surfaces, such as bearing rings or sealing shims. In order to increase the economic efficiency of this process, it has to be advanced permanently. The temperature in the contact zone of most grinding processes has a huge influence on the process efficiency and the workpiece qualities. In contrast to most grinding processes these influences are unknown in double face grinding with planetary kinematics. The application of standard measuring equipment is only possible with high effort due to the inaccessibility of the working space during the machining process. Furthermore, measurement of the workpieces temperature in the considered machining system is not reported. Due to that fact, the intensive cooling has so far been the only method to avoid the occurrence of thermal defects especially in case of brittle ceramic materials. The influence of the mean cutting speed, the tools' cutting performance and the coolant flow on the temperature change of the workpieces made of Al2O3 ceramic materials was investigated with the use of a newly developed method. The first empirical approach to predict the change in temperature of the ceramic workpieces while processing is proposed. The developed measuring method can be used for obtaining experimental temperature data in other processes, such as polishing and lapping for which only theoretical models exist.