Structural characteristics of the part the material of the part is duralumin LY12, with good cutting performance. It belongs to a typical thin-walled disc structure, with large overall dimensions, the thickness of peripheral and internal ribs is only 2mm, and the depth of cavity is 27mm. If the process scheme or processing parameters are not set properly, the part is easy to deform and cause out of tolerance in size. Positioning and clamping of parts during finish machining cavity in order to make the workpiece can be clamped quickly and correctly on the machine tool, and there is no need to align one by one when machining a batch of workpieces, so the automobile parts processing manufacturer will adopt the positioning method of one side and two pins. For some thin-walled parts, it is easy to deform, so when clamping the workpiece, the pressing plate should be pressed on the part with good rigidity of the workpiece and distributed as evenly as possible to ensure the reliability of clamping, and the clamping force should be appropriate to prevent damaging the positioning of the workpiece or causing unacceptable deformation of the workpiece. Its specific positioning and clamping.