Hex Nut

Hex Nut
  • Product description:A nut (commonly known as a "screw cap") is a component used in conjunction with bolts or studs to connect and fasten mechanical parts. It is mostly applied in occasions that require frequent assembly

Materials Used in Manufacturing

  • Alloy steels: 40Cr, 35K
  • Carbon steels: 45# steel, Q235 (A3 steel)
  • Stainless steel
  • Other materials (e.g., plastic-steel for specific scenarios)

Hardness Grades

4, 5, 6, 8, 10, and 12 grades

Core Definition

A nut is a fastener with internal threads, designed to mate with bolts for connecting mechanical components. It can also be used with studs to transmit motion or power in mechanical systems. As an essential component in all mechanical manufacturing processes, nuts fasten parts by screwing onto bolts or studs.

Classification of Nuts

Nuts are categorized by multiple criteria, including standards (regional specifications), materials, and thread sizes:

1. By Regional Standards

Common standards include Chinese (GB), British (BS), American (ANSI/ASME), and Japanese (JIS) standards.

2. By Material

  • Carbon steel nuts
  • High-strength alloy nuts
  • Stainless steel nuts
  • Plastic-steel nuts

3. By Product Attributes & Standards

  • Ordinary nuts
  • Non-standard nuts
  • Old GB standard nuts
  • New GB standard nuts
  • American standard nuts
  • British standard nuts
  • German standard (DIN) nuts

4. By Thread Size & Identification

Thread specifications vary by standard, and only nuts and screws/bolts of matching specifications can be used together:
  • Metric system (GB, DIN, JIS): Marked with "M" + number (e.g., M8, M16). For example, an M3-0.5 nut has an inner diameter of approximately 3mm, with a thread pitch (distance between two adjacent thread crests) of 0.5mm.
  • American standard: Marked with "#" + number or fractions (e.g., 8#, 10#, 1/4", 3/8"). American standard nuts can only mate with American standard external threads.
  • British standard: Marked with fractions (e.g., 1/8", 1/4", 3/8").

Detailed Nut Types & Corresponding Standards

Nut Type Corresponding Chinese Standard (GB)
Square nut (Grade C) GB 39-88
Hexagon nut (Grade C) GB/T 41-2000
Thick hexagon nut GB 56-88
Wing nut GB 62-88
Ring nut GB 63-88
Combined acorn nut GB 802-88
Hexagon nut with spherical top GB 804-88
Lock nut (clinch type) GB 805-88
Knurled high nut GB 806-88
Knurled thin nut GB 807-88
Extra-thin fine-thread small hexagon nut GB 808-88
Inserted round nut GB 809-88
Small round nut GB 810-88
Round nut GB 812-88
Round nut with holes on end face GB 815-88
Round nut with holes on side GB 816-88
Slotted round nut GB 817-88
Type 1 hexagon lock nut with non-metallic insert GB/T 889.1-2000
Type 1 fine-thread hexagon lock nut with non-metallic insert GB/T 889.2-2000
Acorn nut GB 923-88
Type 1 hexagon nut GB/T 6170-2000
Type 1 fine-thread hexagon nut GB/T 6171-2000
Thin hexagon nut GB/T 6172.1-2000
Thin hexagon lock nut with non-metallic insert GB/T 6072.2-2000
Fine-thread thin hexagon nut GB/T 6173-2000
Thin hexagon nut without chamfer GB/T 6174-2000
Type 2 hexagon nut GB/T 6175-2000
Type 2 fine-thread hexagon nut GB/T 6176-2000
Hexagon flange nut GB/T 6177.1-2000
Fine-thread hexagon flange nut GB/T 6177.2-2000
Type 1 slotted hexagon nut (Grade A & B) GB 6178-86
Type 1 slotted hexagon nut (Grade C) GB 6179-86
Type 2 slotted hexagon nut (Grade A & B) GB 6180-86
Thin slotted hexagon nut (Grade A & B) GB 6181-86
Type 2 hexagon lock nut with non-metallic insert GB/T 6182-2000
Hexagon flange lock nut with non-metallic insert GB/T 6183.1-2000
Fine-thread hexagon flange lock nut with non-metallic insert GB/T 6183.2-2000
Type 1 all-metal hexagon lock nut GB/T 6184-2000
Type 2 all-metal hexagon lock nut GB/T 6185.1-2000
Type 2 fine-thread all-metal hexagon lock nut GB/T 6185.2-2000
Type 2 all-metal hexagon lock nut (Grade 9) GB/T 6186-2000
All-metal hexagon flange lock nut GB/T 6187.1-2000
Fine-thread all-metal hexagon flange lock nut GB/T 6187.2-2000
Type 1 fine-thread slotted hexagon nut (Grade A & B) GB 9457-88
Type 2 fine-thread slotted hexagon nut (Grade A & B) GB 9458-88
Fine-thread thin slotted hexagon nut (Grade A & B) GB 9459-88
Welded square nut GB/T 13680-92
Welded hexagon nut GB/T 13681-92
Flat head rivet nut GB/T 17880.1-1999
Countersunk head rivet nut GB/T 17880.2-1999
Small countersunk head rivet nut GB/T 17880.3-1999
120° small countersunk head rivet nut GB/T 17880.4-1999
Flat head hexagon rivet nut GB/T 17880.5-1999
Hexagon nut for precision machinery GB/T 18195-2000

Key Notes

  • Thread Compatibility: Nuts and bolts must match in thread standard (metric/American/British), nominal diameter, and pitch to ensure secure connection. Mismatched threads may cause assembly failure or looseness.
  • Standard Application: Chinese national standards (GB) are widely used in domestic machinery manufacturing; American (ASME) and German (DIN) standards are common in imported equipment or international projects.
  • Material Selection: Choose materials based on environmental conditions (e.g., stainless steel for corrosion-prone environments, high-strength alloys for heavy-load scenarios) and hardness grades based on load requirements.