Kesle GB/T 6171 Hexagon Nuts Serve High-Precision Mechanical Connections.
I. Basic Information
Product Name: GB6171 Type A Class 1 Hexagonal Nut
Implementation Standard: GB/T 6171-2016 (current latest version)
Specification Range: Thread size: M1.6~M16 (Class A precision is mainly applicable to thread diameters ≤16mm; larger diameters are generally Class B).
II. Structural and Precision Features
Structural Type: Type 1 hexagonal nut (standard hexagonal structure, no special grooves or through-hole designs). Key dimensions such as across flats width (s) and thickness (m) are strictly implemented in accordance with standards.
Precision Grade: Class A represents high precision, with a thread tolerance of 6H. Dimensional tolerances for across flats width, thickness, etc., are smaller (superior to Class B), and the surface roughness is lower (usually Ra≤3.2μm), making it suitable for precision connection scenarios.
III. Materials and Performance
Material Selection: Materials are matched according to performance grades, usually including:
- Carbon steel: such as 35# steel, 45# steel (suitable for performance grades 6, 8, etc.), subjected to quenched and tempered heat treatment;
- Stainless steel: e.g., 304 (A2-70), 316 (A4-70), suitable for corrosion-resistant scenarios;
- Copper/aluminum: e.g., brass (CU2), aluminum alloy (AL4), suitable for conductive and lightweight applications.
Mechanical Performance: Meets the requirements of specified performance grades (6, 8, 10, A2-70, etc.):
- Yield load: Threads show no plastic deformation under specified loads;
- Hardness: For example, the hardness of Grade 8 is 22~32HRC; the tensile strength of A2-70 is ≥700MPa;
- Corrosion resistance: Stainless steel/copper materials pass salt spray tests (e.g., 304 stainless steel can resist red rust for ≥48 hours).
IV. Surface Treatment
Options based on application environment:
- Carbon steel: Zinc plating (color zinc, white zinc, salt spray resistance ≥72 hours), chrome plating (bright and wear-resistant), phosphating (rust-proof primer), dacromet (high corrosion resistance, suitable for outdoor use);
- Stainless steel: Passivation treatment (enhances corrosion resistance);
- Copper/aluminum: Natural color (for conductive scenarios) or nickel plating (improves wear resistance).
V. Application Scenarios
Due to its high Class A precision and good surface quality, it is often used in occasions requiring strict connection precision and reliability:
- Precision machinery and equipment (e.g., machine tools, instruments and meters);
- Automotive parts (engines, transmission connections);
- Electronic equipment (components requiring low-tolerance connections);
- Building steel structures (matching high-precision bolts).
VI. Quality Control
- Dimensional inspection: Verify across flats width, thickness, and thread precision through 2D measuring instruments and thread go/no-go gauges (6H);
- Performance testing: Check hardness with hardness testers and verify load with tensile testing machines;
- Visual inspection: No cracks, burrs, or rust, and surface roughness meets Class A requirements.
GB6171 Type A nuts ensure interchangeability and reliability through standardized production, serving as common fasteners for high-precision threaded connections in the industrial field.
