When it comes to the accuracy of machine tool of large size steel ball, except for the assembly accuracy of spindles, radical runout and end jump, it also includes the concentricity and depth of parallelism. The reason of vibrating when manufacturing is the accuracy of the machine tools, which can cause steel ball to move irregularly and make the large steel ball lose the capacity for size selection. Finally destroy the geometric accuracy and surface quality (see table 1). Although we change the manufacture specification and prolong the manufacture time of steel ball, they cannot improve the geometric accuracy effectively. Thus in order to improve the manufacture quality of steel ball, it is one of the solutions to improve the accuracy of the machine tools. However, the over pursue to the accuracy will increase the cost of manufacture and repair.
Table 1. Relationship of the machine tools precision and the steel ball billet precision