The most important link in the development and design of fasteners is quality control. There are several major checkpoints from incoming materials to finished product shipments, and these major checkpoints have different inspection methods. First of all, the feed is related to appearance, size, elements, performance, harmful substance detection, etc.; the process is more about appearance, size, knocking test, forging streamline; heat treatment is more about appearance, hardness, torque, tension , metallography, etc.; surface treatment is more about some hydrogen embrittlement tests, coatings, salt spray, etc., including a harmful substance test for shipments. In terms of size and appearance inspection, the common ones are quadratic element, contour measuring instrument, three-coordinate measuring instrument, image sorting machine (this is a full selection machine); in terms of mechanical and chemical testing, there are mainly hardness machines (Rocket and Vickers) ), tensile machine, metallographic microscope; for material testing, there is a spectrum analyzer and salt spray testing machine.