In order to increase the stiffness and accuracy of the roller linear guide pair during motion, it can be achieved by applying pre tension to the linear guide pair.

When designing, the size of the rollers should be slightly larger than the distance between the slider raceway and the guide rail raceway, so as to create an interference fit between the rollers and the raceway. This will cause contact deformation and contact force in the contact area between the rollers and the raceway, and this internal contact force is called the preload force.

Due to the pre tightening force, contact deformation occurs between the rollers and the raceway, thereby eliminating the gap between the rollers and the guide rail and slider. Therefore, pre tightening force can improve the error equalization effect of the linear guide rail, thereby improving the accuracy of the guide rail pair.

At the same time, the interference fit between the rollers and the raceway allows the guide rail pair to bear four rows of rollers simultaneously when subjected to loads in different directions. Therefore, compared with no preload force, the rigidity of the guide rail pair is much higher. However, if the preload force is too large, it will cause excessive stress between the rollers, sliders, and guide rails, shortening the working life of the linear guide rail. So, an appropriate amount of preload can improve the performance of the roller linear guide pair.