Nut - Other Nut

Introduction to Nuts:

1. Material The material of the nut corresponds to the bolt height to ensure matching strength and corrosion resistance. Common materials include:

Carbon Steel: The most widely used. Classified by strength grade into 4, 6, 8, 10, and 12 (corresponding to bolt grades 4.8 to 12.9). Surface treatments are mostly galvanizing (white zinc, color zinc), blackening, or Dacromet coating to improve rust resistance.

Alloy Steel: Adding elements such as chromium and molybdenum to carbon steel results in higher strength and fatigue resistance. Commonly used in high-strength connections (such as grade 10 and 12 nuts) in conjunction with high-strength bolts.

Stainless Steel: Excellent corrosion resistance and a bright appearance. Common grades include SUS304 (general corrosion resistant) and SUS316 (chloride ion resistant, suitable for marine environments). Strength grades are typically A2-70, A4-80, etc.

Non-ferrous metals: Such as brass, copper, and aluminum. Commonly used in electrical equipment (good conductivity), bathroom pipes (rust-proof and aesthetically pleasing), or precision instruments requiring antimagnetic properties.

Engineering plastics: such as nylon and polyoxymethylene (POM). They are insulating, lightweight, do not damage threads, and require no lubrication. They are commonly used in electronic equipment, household appliances, or applications requiring protection against electrochemical corrosion.

2. Main Types

Nuts come in a wide variety of types, which can be classified according to their functional characteristics, anti-loosening methods, and shape:

By Shape and Structure

Hexagonal Nuts: The most standard and universal type. Used with hexagonal bolts, easy to tighten with a wrench, suitable for most mechanical assembly scenarios.

Thin Hexagonal Nuts: Thinner in thickness, often used in space-constrained areas, or as lock nuts in conjunction with ordinary nuts (double nut anti-loosening), and can also be used when the thread length of the connected parts is insufficient.

Round Nuts: Circular in shape, with grooves or slots on the outer circumference, usually used with locking washers, mostly for fixing bearings and shaft ends.

Square Nut: Square in shape, providing a larger contact area when mated with bolts. Commonly used for simple structures and high-stress equipment, or for installing channel steel and guide rails.

By Anti-Loosening Function:

Nylon Anti-Loosening Nut: A nylon ring is embedded in the top of the nut. When the bolt is tightened, the nylon ring is compressed and deformed, generating strong friction, effectively preventing vibration-induced loosening. Suitable for applications requiring long-term anti-loosening.

Flange Nut: The nut has a flange face at the bottom with anti-slip teeth, increasing the contact area. This disperses pressure and provides anti-loosening protection without the need for an additional washer.

Lock Nut (All-Metal Anti-Loosening): By deforming the top or sidewalls of the nut non-circularly (e.g., flattening, narrowing), the threads elastically deform, creating a continuous locking force. Suitable for high-temperature environments (nylon rings will fail at high temperatures).

Slotted Nut: A groove is cut into the top for use with a cotter pin to secure the nut to the bolt. It is a reliable mechanical anti-loosening method, commonly used in critical connections (such as wheel bearings and steering mechanisms).

By Special Function:

Cap Nuts: With a hemispherical or hexagonal cap-shaped top, they offer an aesthetically pleasing appearance after installation and protect exposed threads from corrosion. Commonly used in automotive wheel hubs, guardrail ends, and other areas requiring sealed threads.

Wing Nuts: With flaps on both sides, they can be manually tightened without tools. Commonly used in areas requiring frequent disassembly and assembly (such as clamps, lamps, and instrument covers).

Weld Nuts: With raised dots or bosses, they are directly welded to metal sheets using resistance welding, facilitating rapid subsequent bolt assembly. Widely used in automotive bodies and sheet metal chassis.

Insertion Nuts: Pre-embedded in plastic, wood, or light alloy parts, providing high-strength internal threads. Common types include copper inserts (injection-molded embeddings) and self-tapping threaded nests.

T-Nuts: T-shaped, they slide into grooves in aluminum profiles, enabling rapid assembly of profile frames with bolts. Widely used in industrial aluminum profile structures.

3. Application Areas

Nuts are used in almost all industrial and daily life scenarios requiring detachable connections:

Construction Engineering and Infrastructure: High-strength hexagonal nuts (used in conjunction with high-strength bolts) are widely used in large structures such as steel bridges, high-rise buildings, high-speed rail tracks, and tower cranes, as well as anchor nuts embedded in concrete. In these scenarios, the strength grade and anti-loosening performance of the nuts directly affect structural safety.

Transportation: Flange nuts, slotted nuts, or nylon anti-loosening nuts are commonly used in critical components such as automobile engines, chassis suspensions, and wheel hub fixations to resist continuous vibrations during vehicle operation; railway rail connections use specialized nuts in elastic clip fastener systems.

Machinery and Industrial Manufacturing: Hexagonal nuts and lock nuts are standard equipment in various machine tools, construction machinery, and agricultural machinery. Welding nuts are widely used in the assembly of automobile bodies and sheet metal casings of home appliances, significantly improving production line efficiency.

Electronics and Precision Instruments: Miniature copper insert nuts or precision thin nuts are used inside mobile phones, laptops, cameras, etc., requiring both strength and space constraints and lightweight design. Nylon nuts are also commonly used for circuit board mounting due to their insulation properties.

Furniture and Everyday Products: IKEA and other furniture manufacturers extensively use embedded nuts (such as furniture pre-embedded nuts) for easy assembly and disassembly; wing nuts are commonly found in table lamps, fans, and other household items requiring manual adjustment.

New Energy and Specialty Fields: Wind turbine blade and hub connections, as well as tower flange connections, use oversized, high-strength anti-loosening nuts with extremely high fatigue and corrosion resistance; photovoltaic brackets extensively use stainless steel flange nuts to withstand long-term outdoor exposure to sun and rain.