Set screws are specialized mechanical components used to fix the relative position of parts and prevent axial or circumferential movement. Unlike traditional bolts, they typically lack a head and nut structure. Instead, they are threaded into the mating part and utilize their special end (such as a conical, flat, or concave end) to directly bear against the shaft or hole, thereby transmitting torque and achieving precise positioning and anti-loosening. These components have a compact structure and do not protrude from the assembly surface. They are widely used for axial positioning and circumferential fixing of parts such as bushings, handles, gears, and bearings, and are indispensable functional basic components in precision machinery, molds, instruments, and transmission systems.