Inspection method: visual inspection, whetstone polishing
Type A defect: It is worn through and is clearly visible on the outer surface, which is immediately visible to all customers. The stamped parts must be frozen immediately after such stamping is discovered
Type B defects: It can be seen and touched, and it can be proved after polishing in disputed areas that such defects are acceptable in areas III and IV. Type C defects: It can be seen after polishing with oilstone, and stamping parts with such defects are acceptable.