Hex Nut Grade And Classification
Hex nut is classified into I type, II type and thin type according to the nominal thickness. Nuts of class 8 or higher are type I and type II.
The type I Hex nut is the most widely used, and the I nut is divided into A, B, and C grades. The A and B nuts are suitable for machines, equipment, and structures with small surface roughness and high precision requirements. The C-class nuts are used on machines, equipment or structures whose surfaces are rough and which do not require high precision; Type B Hex nut nuts are thicker and are often used where mounting and dismounting are often required.
I-nut refers to the ordinary Hex nut with a nominal height m ≥ 0.8D. Its type size should meet the requirements of GB/T 6170;
The height of type II nut is higher than that of type I nut, and the size of its type should meet GB/T6175. There are two purposes for adding a type II nut: One is to obtain a relatively inexpensive nut that does not require heat treatment by increasing the height of the nut.
Because the 8-stage I-nut with D ≤ M16 does not need to be heat-treated, among the 8-stage nut, only the D>M16~39 specification uses the II-type nut.
Obviously using a non-heat treated type I nut does not meet the mechanical performance requirements of the 9th nut.
Another purpose of the Type II nut is to obtain a tougher grade 12 nut.
As the height of the nut increases, a guaranteed stress index can be achieved at a lower quenched and tempered hardness, thus increasing the toughness of the nut.
National Standard for Nuts GB41 I Hex nut - Class C GB6170,
Type I Hex nut - Class A, Class B GB6171,
Type I Hex nut - fine tooth - Class A, B GB6172 Hex nut,
Thin nuts - A, B - chamfers GB6173Hex nut,
Thin nuts - fine teeth - A, B GB6174Hex nu,
t Thin Nut - Class B - No chamfer GB6175,
Type II Hex nut - Grade A, Grade B GB6176,
Type II Hex nut - fine tooth - A, B grade GB6177Hex nut,
Flange face nut - Class A GB56Hex nut,
Thick nut GB1229 Hex nut (high strength steel structure) Bolt coarse thread and fine thread usage;
(1) Fine thread retraction is good for anti-vibration, easy to adjust the gap, but the lock mother force is worse than coarse teeth. It is suitable to adjust the gap or torque place.
(2) The coarse thread self-locking ability is inferior to the fine tooth retraction, but the lock mother force is greater than the fine teeth. Generally there is no special requirement for coarse thread. Coarse thread: After M, it is directly followed by large diameter of the thread, without marking the pitch, with or without marking pitch, which is the difference between the ordinary fine thread and ordinary coarse thread. Metric bolts are 4.6, 4.8, 5.8, 6.8, 8.8 , 9.8, 10.9, 12.9.
The metric nut grades are: 4,5,6,8,10,12 where 4,5 is the strength rating of the thin nut.Nut A, B, C class comparable to the American G2; G5; G8 performance equivalent, J995 stipulates that the performance level between the two is basically the same!
I-nut thread specifications are M1.6~M64 performance levels 6, 8, 10, A2-50, A2-70, A4-50, A4-70, CU2, CU3 and AL4. Product grades are A and B grades, and A grades are used for specifications less than or equal to M16; Class B is for specifications larger than M16! (here A; B refers to the accuracy level)
Type II nut thread specifications M5 ~ M36, performance levels 9 and 12, Product grades are A and B grades, and A grades are used for specifications less than or equal to M16; Class B is for specifications larger than M16! (here A; B refers to the accuracy level)
Because of the high performance level of type 2, the thickness of the nut is relatively thick. The bolt performance grade is divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. 8.8 or above bolts are made of low carbon alloy steel or medium carbon steel and heat treated (quenched and tempered), Commonly referred to as high-strength bolts, the rest are commonly referred to as ordinary bolts.
Bolt performance grade labels are composed of two parts, which respectively represent the nominal tensile strength value and yield ratio of the bolt material. For example, a bolt with a performance rating of 4.6 means:
Performance grade 4.6 bolts, its meaning
1. Bolt material nominal tensile strength up to 400MPa;
2. The yield ratio of bolt material is 0.6;
3, the nominal yield strength of bolt material up to 400 × 0.6 = 240MPa level
Performance grade 10.9 high-strength bolts are heat treated to achieve:
1. The bolt material has a nominal tensile strength of 1000MPa;
2. The yield ratio of bolt material is 0.9;
3, the nominal yield strength of bolt material reaches 1000×0.9=900MPa grade
The meaning of bolt performance level is an international standard. Bolts of the same performance level, regardless of their material and origin, have the same performance. When selecting a product, simply confirm the performance level.
The type I Hex nut is the most widely used, and the I nut is divided into A, B, and C grades. The A and B nuts are suitable for machines, equipment, and structures with small surface roughness and high precision requirements. The C-class nuts are used on machines, equipment or structures whose surfaces are rough and which do not require high precision; Type B Hex nut nuts are thicker and are often used where mounting and dismounting are often required.
I-nut refers to the ordinary Hex nut with a nominal height m ≥ 0.8D. Its type size should meet the requirements of GB/T 6170;
The height of type II nut is higher than that of type I nut, and the size of its type should meet GB/T6175. There are two purposes for adding a type II nut: One is to obtain a relatively inexpensive nut that does not require heat treatment by increasing the height of the nut.
Because the 8-stage I-nut with D ≤ M16 does not need to be heat-treated, among the 8-stage nut, only the D>M16~39 specification uses the II-type nut.
Obviously using a non-heat treated type I nut does not meet the mechanical performance requirements of the 9th nut.
Another purpose of the Type II nut is to obtain a tougher grade 12 nut.
As the height of the nut increases, a guaranteed stress index can be achieved at a lower quenched and tempered hardness, thus increasing the toughness of the nut.
National Standard for Nuts GB41 I Hex nut - Class C GB6170,
Type I Hex nut - Class A, Class B GB6171,
Type I Hex nut - fine tooth - Class A, B GB6172 Hex nut,
Thin nuts - A, B - chamfers GB6173Hex nut,
Thin nuts - fine teeth - A, B GB6174Hex nu,
t Thin Nut - Class B - No chamfer GB6175,
Type II Hex nut - Grade A, Grade B GB6176,
Type II Hex nut - fine tooth - A, B grade GB6177Hex nut,
Flange face nut - Class A GB56Hex nut,
Thick nut GB1229 Hex nut (high strength steel structure) Bolt coarse thread and fine thread usage;
(1) Fine thread retraction is good for anti-vibration, easy to adjust the gap, but the lock mother force is worse than coarse teeth. It is suitable to adjust the gap or torque place.
(2) The coarse thread self-locking ability is inferior to the fine tooth retraction, but the lock mother force is greater than the fine teeth. Generally there is no special requirement for coarse thread. Coarse thread: After M, it is directly followed by large diameter of the thread, without marking the pitch, with or without marking pitch, which is the difference between the ordinary fine thread and ordinary coarse thread. Metric bolts are 4.6, 4.8, 5.8, 6.8, 8.8 , 9.8, 10.9, 12.9.
The metric nut grades are: 4,5,6,8,10,12 where 4,5 is the strength rating of the thin nut.Nut A, B, C class comparable to the American G2; G5; G8 performance equivalent, J995 stipulates that the performance level between the two is basically the same!
I-nut thread specifications are M1.6~M64 performance levels 6, 8, 10, A2-50, A2-70, A4-50, A4-70, CU2, CU3 and AL4. Product grades are A and B grades, and A grades are used for specifications less than or equal to M16; Class B is for specifications larger than M16! (here A; B refers to the accuracy level)
Type II nut thread specifications M5 ~ M36, performance levels 9 and 12, Product grades are A and B grades, and A grades are used for specifications less than or equal to M16; Class B is for specifications larger than M16! (here A; B refers to the accuracy level)
Because of the high performance level of type 2, the thickness of the nut is relatively thick. The bolt performance grade is divided into more than 10 grades such as 3.6, 4.6, 4.8, 5.6, 6.8, 8.8, 9.8, 10.9, and 12.9. 8.8 or above bolts are made of low carbon alloy steel or medium carbon steel and heat treated (quenched and tempered), Commonly referred to as high-strength bolts, the rest are commonly referred to as ordinary bolts.
Bolt performance grade labels are composed of two parts, which respectively represent the nominal tensile strength value and yield ratio of the bolt material. For example, a bolt with a performance rating of 4.6 means:
Performance grade 4.6 bolts, its meaning
1. Bolt material nominal tensile strength up to 400MPa;
2. The yield ratio of bolt material is 0.6;
3, the nominal yield strength of bolt material up to 400 × 0.6 = 240MPa level
Performance grade 10.9 high-strength bolts are heat treated to achieve:
1. The bolt material has a nominal tensile strength of 1000MPa;
2. The yield ratio of bolt material is 0.9;
3, the nominal yield strength of bolt material reaches 1000×0.9=900MPa grade
The meaning of bolt performance level is an international standard. Bolts of the same performance level, regardless of their material and origin, have the same performance. When selecting a product, simply confirm the performance level.
