Most Bare Engine materials use high-strength selected 45 steel. 40Dr steel, etc., which are quenched and tempered to improve cutting performance and impact resistance.

The hardness requirements for 45 steel are HB217~293, and 40Dr is HB223~280. There are also applications of ductile iron and powder metallurgy technology to reduce the cost of blanks.

Bare Engine blanks are generally produced by forging, and there are two forms of blanks: one is the body. Forge the cover separately; the other is to separate the body.

The cover is forged into one, and it is cut again during processing or expanded and broken by the expansion fracture process. In addition, in order to avoid blank defects, 100% hardness measurement and inspection are required.

The correct selection of rough reference and the reasonable design of the initial positioning fixture are a key issue in the processing process.

When positioning the large and small heads of MG Roewe Maxus Engine, the rough reference positioning method of the Bare Engine reference end face and the outer circle of the small head blank three points and the outer circle of the large head blank two points is adopted.

This can ensure that the size of the head holes and the processing allowances of each processing surface are uniform, ensure that the Bare Engine is weighed evenly, and ensure the shape and position of the parts assembly.