Effects of axial preloading of angular contact ball bearings on the dynamics of a grinding machine spindle system

A mathematical model based on a five degrees of freedom dynamic system is utilized to study the effects of axial preloading of angular contact ball bearings on the vibration behavior of a grinding machine spindle. The grinding forces (as a function of grinding wheel wear rate percentage for five different workpiece materials) were used to simulate external loading on the grinding machine spindle. The results show that the initial axial preload applied on the bearings plays a significant role to reduce the vibration levels of the grinding machine spindle system and consequently results in better accuracy for the finished surfaces. The vibration levels of grinding machine spindle system increases as wheel wear rate percentage increases and/or the hardness of the workpiece material increase. This analysis can be used to calculate the optimum initial axial preload in order to obtain high accuracy for surface finish.