Twin axes synchronous controlled type CNC crankshaft pin grinder has been widely used, but grinding mechanism with this type of pin grinder is not cleared well. In this study, the grinding mechanism is analyzed, and it is found that the cylindrical plunge grinding process carries on. From the investigation of substantial surface speed of both the wheel and the workpiece, grinding speed ratio is formulated. Furthermore, a simulation method, which predicts the grinding results, is developed. In order to realize high precision pin grinding, two methods, which control workpiece rotation speed adequately, are proposed, such as the controlled grinding speed ratio method and the controlled residual stock method. From the analysis, it is made clear that stable grinding force and surface roughness are generated by the controlled grinding speed ratio method, and also high dimensional accracy will be realized by the controlled residual stock method.
