The nut is used to screw together the bolt or screw to fasten parts. All manufacturing machinery must use an element according to the different materials, is divided into carbon steel, stainless steel, non-ferrous metals (such as copper) and other types of.

From the head and screw (cylinder with external thread) is composed of two parts of a class of fasteners, should be matched with a nut is used for fastening and connecting, two with a through hole parts. This kind of connection form of said connecting bolts. As the nut is screwed on the screw from, also can make the two parts separately, so the bolt connection is detachable connection.

Screw is the use of physics and mathematics principle object inclined plane circular rotation and friction, step by step to fasten utensil machine tool. Screw generally, is an industrial necessity in daily life, used in a wide range of application areas, small to watches glasses, to train the ship, the space shuttle, not a lack of it.

A thin metal pad on the nut or the screw head and is connected between the. The washer is divided into: flat washer level -C, -A and C large washers plain washers, -C, small washer, flat washer, flat washer, chamfered - a grade, steel structure with high strength gasket, a spherical washer, taper washers, square taper washers for steel etc.

Thread rod
There is a thread of a round bar, the bar can be of steel, copper or aluminum and other materials, the thread can be ordinary triangle thread, may also be a trapezoidal thread etc. It can be have chamfer or not. It includes double-end stud.