Analysis of Flexure Tolerances on Repeatability and Virtual Play in Overconstrained Ball Screw and Linear Guide Mechanisms for Selection of Optimal Manufacturing Process

Abstract

In mass-produced precision machinery, achieving high accuracy while minimizing costs is essential. The Ball Screw and Linear Guide (BSLG) mechanism, provides a large translation at a low cost but faces challenges in accuracy, particularly in terms of repeatability and virtual play. This study addresses these challenges by integrating a flexure system designed to eliminate overconstraints in the BSLG mechanism to improve its accuracy. Additionally, we explore cost-effective manufacturing processes for producing the flexure system without compromising its performance. A model was developed to calculate the virtual play of a BSLG mechanism, which was validated through measurements on an X-stage BSLG mechanism. The integration of the flexure system resulted in a 55% reduction in virtual play (from 3961nm to 1790nm) and 52% reduction in unidirectional repeatability (from 909nm to 441nm). Importantly, alternative manufacturing processes, despite introducing stiffness variations, had a negligible impact on the overall performance, enabling cost reduction without sacrificing accuracy. This study demonstrates the effectiveness of using flexure systems to remove overconstraints and enhance precision. Given the widespread application of the BSLG mechanism, the flexure system designed in this article can improve machinery across a wide range of fields.