PRODUCTION NOTE: 1. Select the tungsten steel materials and specifications size to make the screws or nuts mold correctly. 2.According to the difference of the forming difficulty,size,length of screws and nuts,rational design of the mold structure,multi-station and nut mold should be allocated on a reasonable basis the upsetting deformation and the number of molding. 3.The mold fine craftsmanship,accurate size,bore diameter to match the finish mirror requirements. 4.Interference voltage distribution margin,select the appropriate alloy taper size. 5.Shell steel sleeve must be rigid and good heated,and the hardness range should be between 42°c-48 °c after the vacuum heat treatment.