However, in order to obtain accurate tooth profile, pitch and tooth division accuracy, all machine tools that are composed of a transmission chain for moving and processing gears and threads must ensure that the transmission chain has a certain accuracy.

There are two methods for checking the transmission error of the machine tool transmission chain: indirect method and direct method:

(1) The indirect method is to process a product, such as a gear or screw, to measure the workpiece according to the rules of the machine tool manual, and use the method of checking the quality of the workpiece to determine whether the transmission error of the machine tool transmission chain can process the workpiece with the required accuracy level. . This method reflects the generalized errors of the construction process, including not only the transmission errors of the machine tool transmission chain, but also the errors of other elements.

(2) Direct method There are two types of static measurement method and dynamic measurement method.