A modified ball screw lapping method and optimized lapping factors for ideal surface quality

In order to meet the high precision requirement in various mechanical applications, ball screws are being lapped as a finishing process to improve the travel variation and surface quality. However, the existing manufacturing method is labor intensive. It depends on an operator's skill and experience and is very complex, time consuming with low production efficiency. The aim of this study is finding a modified lapping method to improve the lapping effect, increase efficiency and change the present labor-intensive situation. In addition, the effects of main lapping factors on the surface quality of a ball screw will be investigated, such as friction torque, rotational speed, abrasive particulate size and lapping time. A new lapping tool was installed on a specially designed friction torque test machine, which can control the rotation of a screw and monitor the friction torque applied on the screw dynamically. A set of orthogonal experiments were conducted on the test machine and the travel variation, surface roughness and residual stress of tested screws were measured after lapping. The measurement results of these three parameters were used to evaluate the lapping effect. Compared with the conventional lapping method, the lapping time of the present method was remarkably shorter, with only tens of minutes to get a good lapping result.