Classification Of Hex Nuts

There are three types of hexagon nuts based on their nominal thickness: I type, II type, and thin type. Additionally, hexagon nuts with a grade above 8 are further classified into two types: type 1 and type II. The most commonly used hexagon nuts are of type I. Type 1 nuts are categorized into three grades: A, B, and C. Grade A and grade B nuts are ideal for machinery, equipment, and structures that demand a smooth surface and high precision. On the other hand, grade C nuts are suitable for applications where rough surfaces and low precision requirements are acceptable. Hence, depending on the specific needs and specifications, different types and grades of hexagon nuts can be chosen for various purposes.

Type 1 nuts are standard hexagonal nuts that have a minimum height of 0.8 times the diameter (m ≥ 0.8D). These nuts should meet the requirements specified in GB/T6170. On the other hand, type 2 nuts have a higher height than type 1 nuts and their type and size should comply with GB/T6170, T6175. The purpose of introducing type 2 nuts is twofold. Firstly, it allows for the production of a cost-effective nut that does not require heat treatment. By increasing the height of the nut, it avoids the need for heat treatment, particularly for grade 8 nuts with diameters (D) less than or equal to M16. Only grade 8 nuts with specifications of D > M16~39 use type 2 nuts. It is important to note that type 1 nuts, which do not require heat treatment, cannot meet the mechanical property requirements of grade 9 nuts.

Secondly, specifying type 2 nuts allows for the production of a more ductile grade 12 nut. By increasing the height of the nut, the desired stress index can be achieved at a lower quenching and tempering hardness, thereby enhancing the toughness of the nut.

Nuts can be classified based on tooth spacing, such as standard, regular, fine, very fine, and cross teeth. Classification can also be done based on material, including stainless steel, carbon steel, copper, and iron hexagon nuts. Additionally, nuts can be classified based on thickness as hexagonal thick nuts or hexagonal thin nuts. Finally, nuts can also be categorized based on their method of use, such as hot-melt copper nut, hot-pressed copper nut, embedded copper nut, and ultrasonic copper nut.