Classification of hex nuts


Hex nuts are classified into Type I, Type II, and Thin […]

Hex nuts are classified into Type I, Type II, and Thin according to the nominal thickness. Nuts of class 8 or higher are divided into two types, type 1 and type II.
  The Type I hex nut is the most widely used, and the Type 1 nut is divided into three grades A, B, and C. The Grade A and Class B nuts are suitable for machines, equipment, and structures with low surface roughness and high precision.

Class C nuts are used on machines, equipment or structures where the surface is rough and the precision is not high. Type 2 hex nuts are thicker and are often used in applications where assembly and disassembly are often required.  Type 1 nut refers to a common hex nut with a nominal nut height of m ≥ 0.8D, and its type size should meet the requirements of GB/T6170;
  The height of the type 2 nut is higher than that of the type 1 nut, and the type size should conform to GB/T6175. There are two purposes for adding a type 2 nut: one is to obtain a relatively inexpensive nut by increasing the height of the nut.
  Because the 8 grade 1 nut of D ≤ M16 does not need heat treatment, among the 8 grade nuts, only the type 2 nut is used for the specification of D > M16~39.
It is clear that the type 1 nut that is not heat treated does not meet the mechanical performance requirements of the class 9 nut. Another purpose of the Type 2 nut is to obtain a 12-stage nut with better toughness. As the height of the nut increases, the guaranteed stress index can be achieved at a lower quenching and tempering hardness, thus increasing the toughness of the nut.