microns as the increment, the ball is sorted and installed on the guide rail respectively, the size of the preload depends on the force acting on the ball. If the force acting on the steel ball is too large in the linear guide, the steel ball will endure the pre-loading time too long, which will cause the slide block movement resistance to increase. In order to improve the sensitivity of the system and reduce the resistance of motion, the pre-load must be reduced accordingly, and the pre-load must be sufficient to improve the accuracy of motion and the retention of precision, these are two sides of the same coin. The Linear Guide rail system is designed to maximize the contact area between the fixed and moving elements, which can not only improve the load-carrying capacity of the system, but also withstand the impact force produced by intermittent or gravity cutting, the action force is widely diffused to enlarge the area of bearing force. In order to achieve this, the guide rail system groove shape has a variety of, there are two representative, one called Gothic, the shape is a semi-circular extension, the point of contact for the apex; the other is a circular arc, the same can play the same role. No matter which structural form, the purpose is only one, strive for more rolling ball radius and guide rail contact.