Introduction to standardized fasteners

Standardized mechanical parts for fastening connections. Standard fasteners mainly include bolts, studs, screws, set screws, nuts, washers and rivets.

There are many structural types of bolts, and the head is mostly hexagonal. For bolts subjected to impact, vibration or variable load, in order to increase flexibility, the smooth rod part is made into thin segments or hollow. The seat end of the stud is screwed into the threaded hole of the connected part, and the nut matched with the nut end is similar to the bolt nut. The structure of the screw is roughly the same as that of the bolt, but the head shape is diverse to adapt to different assembly space, tightening degree and connection appearance. Set screws have different head and end shapes to adapt to different degrees of tightening. There are also many types of nuts, of which hexagon is the most widely used.

The main categories include ordinary screws, machine screws, self tapping screws and expansion screws.

Cap screw used to be limited to full tooth fasteners.

Hex Cap Screw and hex bolt, as the name suggests, are external thread fasteners with hexagonal head, which are designed to rotate with a wrench. According to ASME b18.2.1 standard, the tolerance of head height and rod length of Hex Cap screw is smaller than that of general hex bolt. Therefore, ASME b18.2.1 hex screw is suitable for installation where all hex bolts can be used, including where the large hex bolt is too large to be used.

Socket cap screw (also known as socket head screw or socket head screw) is a screw with a hexagonal inner hole on the head. It can be tightened or loosened only after a hex key (Allen wrench or Allen key) is inserted into the inner hole. The most commonly used hexagon socket head screws are cylindrical head screws, with a head diameter of about 1.5 times the main diameter of the thread (1960 series). Other head types include bottom head cap screw (bottom head cap screw) to make the surface beautiful and countersunk head cap sc