Thermal analysis of creep-feed grinding

Abstract

One of the major problems encountered in industrial experience of creep-feed grinding is thermal damage to the workpiece and grinding wheel. Thus, the application of cutting fluids is especially crucial. In this paper an analytical model of the heat transfer between the wheel, the workpiece surface and the grinding fluids is derived and verified. The model enables the prediction of the maximum surface temperature when grinding fluids are applied, demonstrates the thermal energy partitions between the abrasive wheel, the cutting fluids and the workpiece, and also determines the threshold of the occurrence of film-boiling. Despite its simplicity, the model provides remarkable agreement with published data from experimental investigations and from finite-element analysis, for various creep-feed grinding conditions. The cooling effect of water-based grinding fluids is better than that of oil-based cutting fluids, but the resistance to workpiece burning using water-based cutting fluids is worse than that using oil-based cutting fluids. When cutting fluids are applied in the grinding process, the strong cooling effect of the cutting fluids is apparent. In addition, a CBN grinding wheel shows a better performance than an Al 2O 3 grinding wheel in the avoidance of workpiece burning. The cooling effect of grinding fluid, R c, can be improved by decreasing the effective contact ratio. In general, this effective contact ratio can be achieved by selecting a grinding wheel with a higher porosity of structure number. Further, a shorter dressing time-interval is a better choice for decreasing the wear flat area and thus for improving the cooling effect of the coolant on the workpiece.