A nut is a nut, a part screwed together with a bolt or screw rod for fastening. It is a necessary component for all production and manufacturing machinery There are many kinds of nuts, including carbon steel, high strength, stainless steel, plastic steel, etc According to different national standard numbers corresponding to product attributes, they are divided into ordinary, non-standard, (old) national standard, new national standard, American system, British system, German standard, etc.

Hexagon nuts are divided into type I, type II and thin type according to the nominal thickness. Nuts above grade 8 are divided into type I and type II.

Type I hexagon nuts are the most widely used. Type I nuts are divided into three grades A, B and C. grade A and B nuts are suitable for machines, equipment and structures with small surface roughness and high precision requirements, while grade C nuts are used for machines, equipment or structures with rough surface and low precision requirements; The thickness of type II hexagon nut is relatively thick, and it is often used in occasions where assembly and disassembly are often required.

Common national standards for nuts:

Gb41 type I hexagon nut - grade C

Gb6170 type I hexagon nut - grade A and B

Gb6171 type I hexagon nut - fine thread - grade A and B

Gb6172 hexagon thin nut - grade A and B - Chamfer

Gb6173 hexagon thin nut - fine thread - grade A and B

Gb6174 hexagon thin nut - grade B - without chamfer

Gb6175 type II hexagon nut - grade A and B

Gb6176 type II hexagon nut - fine thread - grade A and B

Gb6177 hexagon flange nut - class A

Gb55 hex thick nut

Gb56 hexagon extra thick nut

Gb1229 large hexagon nuts (high strength for steel structures)

The grades of metric bolts are: 4.6; 4.8; 5.8; 6.8; 8.8; 9.8; 10.9; 12.9.

The grades of metric nuts are: 4; 5; 6; 8; 10; 12 of which 4; 5 is the strength grade of thin nut.