Cap nuts, also known as dome nuts or acorn nuts, feature a closed-end, domed cap that covers the threaded end of a bolt. This design serves a dual purpose: protecting the bolt's threads from dust, moisture, and mechanical damage while providing a sleek, finished appearance. Widely used in automotive, electronics, home appliances, and medical devices, cap nuts combine functionality with aesthetic appeal, enhancing both the durability and visual quality of assembled products.
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Standard
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Country/Region
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Description
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ISO 10511
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International
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Specifies dimensions, tolerances, and general requirements for cap nuts
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DIN 1587
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Germany
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Defines the dimensional and mechanical specifications of cap nuts with metric threads
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ASME B18.2.6
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USA
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Covers inch-series cap nuts, detailing thread types and material requirements
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GB/T 923 - 2009
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China
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Details product specifications for cap nuts used in domestic industrial applications
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JIS B 1181
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Japan
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Japanese standard for cap nuts, including size series and strength ratings
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Grade
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Material
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Tensile Strength (MPa)
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Application Scenarios
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4
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Low-carbon steel (e.g., Q215)
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400
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General household items, light-duty mechanical assemblies
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5
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Low-carbon steel (e.g., Q235)
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500
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Common industrial equipment and office furniture
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8
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Medium-carbon steel (e.g., 45# steel)
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800
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Automotive components, precision instruments
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10
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Alloy steel (e.g., 35CrMo)
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1000
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Heavy machinery, bridge construction, high-load applications
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A2-70 (Stainless Steel)
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304 stainless steel
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700
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Corrosion-resistant environments (food processing, indoor humid areas)
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A4-80 (Stainless Steel)
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316 stainless steel
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800
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Marine engineering, chemical plants, highly corrosive settings
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Nylon / Plastic
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Nylon 6/6, Polypropylene
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-
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Electrical insulation, anti-static environments, lightweight products
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Treatment Method
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Abbreviation
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Description
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Zinc Plating
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Zn
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Basic rust protection (clear, blue, or yellow finishes), suitable for indoor and general industrial use
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Hot-Dip Galvanizing
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HDG
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Superior corrosion resistance, ideal for outdoor, high-moisture, or highly corrosive environments
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Nickel Plating
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Ni
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Enhances appearance and offers moderate corrosion protection, often used in consumer electronics
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Black Oxide Coating
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Black
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Creates a non-reflective, black surface with mild rust resistance, suitable for internal components
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Dacromet Coating
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Dacromet
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Chromium-free, eco-friendly coating with excellent corrosion and heat resistance, favored in automotive and aerospace industries
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Powder Coating
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-
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Provides a durable, colored finish for aesthetic or specific protection needs
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