In the process of using parts wear of parts is caused by long-term friction. When the gap between shaft and hole is worn to a certain extent parts must be replaced. Therefore in the design of products materials with lower hardness and better wear resistance are selected for shaft sleeves and linear ball bushing bearings so as to reduce the wear of shaft and seat. Replace the rubber bush bearing when it is worn to a certain extent thus reducing the cost of replacing the shaft or seat. Generally speaking bushing and seat with interference fit because in any case or can not avoid wear can only prolong the life.