Understand the process of precision machining
   We divide mechanical processing into the following four stages:

   1. Face first, hole second: For parts such as box body, bracket and connecting rod, the plane should be processed first and then the hole should be processed. In this way, the holes can be positioned on the plane to ensure the position accuracy of the plane and the holes, and it is convenient to process the holes on the plane.

   2. Machining the reference surface first: During the processing of the part, the surface as the positioning reference should be processed first, so as to provide a precise reference for the subsequent processing as soon as possible, which is called "reference first".

    3. Finishing processing: The finishing processing of the main surface (such as grinding, honing, precision grinding and rolling processing, etc.) should be carried out at the last stage of the process route. The surface finish after processing is above Ra0.9um, and slight collisions will Damage to the surface. In Japan, Germany and other countries, after the finishing process, you must use flannel to protect it. Never touch the workpiece directly with your hands or other objects, so as to avoid the finishing surface due to the transfer and installation between the processes. Be injured.

    Fourth, divide the processing stage: the surface with high processing quality requirements are divided into processing stages, which can generally be divided into three stages: rough machining, semi-finishing and finishing. The main purpose is to ensure the processing quality; facilitate the rational use of equipment; facilitate the arrangement of the heat treatment process; and facilitate the discovery of blank defects.