Nuts are fasteners used in conjunction with bolts or threaded rods to hold multiple components together. They come in various types and sizes, each tailored for specific applications and requirements. The standard specifications for nuts cover aspects such as dimensions, material properties, thread types, and mechanical performance.
Key Specifications for Nuts
- Dimensional Standards
- ISO 4032: Specifies the dimensions for hex nuts, including their width across flats, thickness, and thread sizes.
- ANSI/ASME B18.2.2: Specifies dimensions for square and hex nuts, including tolerances.
- DIN 934: Specifies the dimensions for metric hex nuts, similar to ISO 4032.
- Material Standards
- ISO 898-2: Specifies mechanical properties for nuts made of carbon steel and alloy steel, including tensile strength, hardness, and impact properties.
- ASTM A194: Covers nuts made from carbon and alloy steel for high-pressure and high-temperature service.
- ASTM A563: Specifies the material and mechanical properties for carbon and alloy steel nuts for general structural and industrial applications.
- Thread Standards
- ISO 68-1: Defines the basic profile for metric threads.
- ISO 261: Specifies general-purpose metric screw threads.
- ASME B1.1: Specifies unified inch screw threads for nuts and bolts.
- Performance Standards
- ISO 2320: Specifies prevailing torque-type steel nuts and their performance requirements.
- DIN 267: Covers the mechanical properties of nuts.
- Coating and Corrosion Resistance
- ISO 4042: Specifies electroplated coatings for threaded fasteners.
- ASTM B633: Covers the electrodeposited coatings of zinc on iron and steel, which can apply to nuts for corrosion resistance.
Common Types of Nuts and Their Specifications
- Hex Nuts (ISO 4032, DIN 934)
- Size Range: M1.6 to M64 (metric), 1/4″-4″ (inch).
- Materials: Carbon steel, stainless steel, brass, etc.
- Usage: General purpose.
- Square Nuts (ANSI B18.2.2)
- Size Range: Similar to hex nuts.
- Materials: Similar to hex nuts.
- Usage: Mainly in wooden structures and for aesthetics.
- Lock Nuts (ISO 7040, ISO 7041)
- Size Range: M3 to M48.
- Materials: Carbon steel, stainless steel, etc.
- Usage: Prevent loosening due to vibration or torque.
- Flange Nuts (ISO 4161)
- Size Range: M5 to M20.
- Materials: Carbon steel, stainless steel, etc.
- Usage: Distribute pressure over a larger area.
- Wing Nuts (DIN 315)
- Size Range: M3 to M12.
- Materials: Carbon steel, stainless steel, brass, etc.
- Usage: Hand-tightening applications where frequent adjustments are required.
Standard Specification Examples
Hex Nut (Metric)
- Standard: ISO 4032
- Dimensions:
- Diameter DDD: 3 mm to 64 mm
- Height mmm: 2.4 mm to 42 mm
- Thread: ISO metric thread (ISO 68-1)
- Material: Steel grades 5, 8, 10 (ISO 898-2)
- Surface Finish: Zinc-plated, plain, etc.
- Mechanical Properties: Tensile strength classes 4, 5, 6, 8, 10 (ISO 898-2)
Hex Nut (Inch)
- Standard: ANSI/ASME B18.2.2
- Dimensions:
- Diameter DDD: 1/4″ to 4″
- Height mmm: 7/32″ to 4″
- Thread: Unified National Coarse (UNC), Unified National Fine (UNF) (ASME B1.1)
- Material: ASTM A563 (carbon and alloy steel grades)
- Surface Finish: Galvanized, plain, etc.
- Mechanical Properties: Grade A, B, C, DH
Summary
Nuts come with various specifications that define their dimensions, materials, thread types, and mechanical properties. Standards like ISO, ANSI, and DIN provide detailed guidelines to ensure compatibility and performance in various applications. Always refer to the specific standard for detailed requirements when selecting nuts for a particular application.
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