(1) Axial size control. The axial direction of the camshaft is located on the thrust surface. Since the axial tolerance of the cam is relatively large, it is generally only necessary to make some adjustments in the workpiece coordinate system after processing a few pieces.

The axial dimension of the crankshaft is based on the end face of the thrust journal. The conventional crankshaft machining process is complicated due to the large number of machining processes and the change of the process reference. With the use of a large number of CNC equipment and measurement systems, most processes can achieve the unification of product benchmarks and process benchmarks. Because the subsequent process of the crankshaft—heat treatment deformation affects the control of the axial dimension of the grinding, it is necessary to regularly perform statistical analysis on the heat treatment deformation law, and adjust the inner milling size according to the result to compensate for the deformation.

(2) External bounce control. Before the rough machining of the cam, the spindle neck must be guaranteed. Take the six-cylinder camshaft as an example. The fourth main spindle neck jump should be ≤0.20mm, and the quality of the keyway should be ensured. Otherwise, the cam profile error and phase instability will be caused after machining. Generally, after processing a batch of about 30 pieces of ADCOLE data and comparing the product process requirements, the difference values are introduced into the CNC system in the form of polar coordinates.

Crankshaft runout error has an impact on crank radius, phase measurement and machining, and affects subsequent grinding quality. Internal milling is a dry processing equipment, which produces large cutting force and cutting heat during machining. The local temperature during cutting is as high as 700 °C, which will cause the release of residual internal stress of hot forging blank, which is easy to cause sudden change of runout error after internal milling. . Under normal circumstances, the quality of the heat treatment of the crankshaft blank can ensure the stability of the batch, statistical analysis of the data of the component runout error, and the beating error required to adjust the eccentric direction to obtain the process requirements.

For the internal milling processing method in which the workpiece is fixed, it is very convenient to realize the active control of the eccentric machining of the spindle neck to obtain the runout error in accordance with the process requirements. Through the statistics of the runout error after a batch of internal milling, it is decomposed into two directions of X and Y to compensate, so as to obtain the stable runout error of the batch.