The central hole of the crankshaft is an important positioning reference for the crankshaft machining process. The common central hole machining method of the crankshaft is the geometric center hole and the mass center hole.

The crankshaft has high technical requirements. The journal diameter tolerance is generally IT6 tolerance, and the journal surface roughness is Ra0.4~Ra0.2μm. Therefore, in order to ensure product quality requirements, the crankshaft must be applied to all journals after rough machining. Finishing of grinding to improve journal accuracy and reduce surface roughness. The traditional grinding method of crankshaft journals is divided into two stages: semi-finishing and fine grinding. However, with the development of blank manufacturing technology and the improvement of roughing equipment processing precision, most of the crankshaft processing plants have cancelled the semi-finishing process. This can shorten the machining process of the crankshaft and reduce the production cost of the crankshaft.

The oil hole of the crankshaft generally has a small hole diameter and a deep depth. It is a deep hole machining, so it is difficult to process. The crankshaft oil hole machining has been gradually processed by gun drilling. The depth of the drill hole used to machine the deep hole can generally be achieved. More than 100 times the diameter, the precision of the gun drilling process can be very high, and the high precision hole can be processed at one time depending on the material to be processed and the different cutting amount.

In order to improve the strength of the crankshaft and increase the wear resistance of the surface, the crankshaft generally needs to strengthen the surface of the journal, the rounded corners, etc. The commonly used strengthening processes include quenching, rolling, nitriding, etc., due to the wide range of quenching and high efficiency. The strengthening effect is good, so quenching has become the main strengthening process at present.