Inclusive estimations of ball screw-based CNC feed drive system over positioning and pre-loading factor

This paper aims to investigate the performance and positioning accuracy of computer numerical controlled (CNC) feed drive system using a ball screw-based pre-loading impact factor.

Initially, axial displacement of support bearings has been computed in relation to the different preload values. Among the computed values, a basic rule equation has been developed for the calculation of elongation in the bearings. The value of displacements computed from the developed equation has been considered as a pre-loading value, and its behavior on the feed drive system has been analyzed.

The elongation of bearings impacts the positioning accuracy and repeatability of the feed drive system and of CNC machines. Next, an analytical model for the rigorous assessment of CNC feed drive system has been designed and developed. The positioning accuracy of CNC machine in relation with different pre-loading values has been analyzed.

The results obtained from these investigations enhance the positioning accuracy of CNC machining centers. The optimum pre-loading value has been analyzed among the available ranges, and it has been proposed that optimal results have been achieved at 5 per cent of dynamic load rating.

This paper proposes improved explorations toward the performance of the CNC machines by optimizing the positioning accuracy through pre-loading. Finally, analytical estimations have been carried out to prove the validity of the proposal.