The most important link in the development and design of fasteners is quality control. There are several major hurdles from input to finished product shipment, and these major hurdles have different inspection methods. First of all, the feed is related to appearance, size, element, performance, hazardous substance detection, etc.; process aspects are more appearance, size, percussion experiment, forging flow line; heat treatment is more appearance, hardness, torque, tension , Metallography, etc.; surface treatment is more of some hydrogen embrittlement tests, coatings, salt spray, etc., including a hazardous substance test when shipped. In the size and appearance inspection, the common ones are the second element, the contour measuring instrument, the three coordinate measuring instrument, the image sorting machine (this is a full selection machine); in the mechanical and chemical inspection, there are mainly hardness machines (Rockwell and Vickers ), tensile tester, metallographic microscope; for material testing, there is a spectrum analyzer and salt spray tester.