When it comes to nuts, most people are familiar with their role as fasteners alongside screws. These essential components are ubiquitous in both daily life and industrial production, highlighting the substantial market demand for nuts.

Despite their prevalence, the vast array of nut types means that, beyond the commonly used ones, many remain unfamiliar, even to seasoned engineers. TorcStark aims to address this knowledge gap by providing a comprehensive list of the main types of nuts in the market. Take up the challenge and see if there’s anything new for you to discover!

Hexagon Head Nut

1. What is an External Hexagonal Nut?

The hexagonal nut serves as a crucial component in conjunction with bolts and screws for fastening purposes. It is categorized into three types based on nominal thickness: Type I, Type II, and Thin Type. Nuts above Grade 8 are further classified into Type I and Type II, with Type I nuts having three grades: A, B, and C.

2. Application Fields

Grade A and Grade B: Suitable for machines, equipment, and structures demanding small surface roughness and high precision.

Grade C: Used in situations involving machines, equipment, or structures with rough surfaces and low accuracy requirements.

Type II Hexagonal Nuts: These are thicker and find application in scenarios where frequent assembly and disassembly are necessary.

Square Nut

1. What is a Square Nut?

A square nut, also known as a square nut or quadrate nut, derives its name from its square shape. This type of nut belongs to the welding nut category, where a specific metal is melted at high temperatures and then welded between two products for secure fastening.

2. Application Fields

The square nut ensures a robust fastening effect, resistant to easy loosening. It finds extensive use in various industries such as road transportation and home building materials. With applications spanning across a multitude of fastening needs, it stands out as a common mechanical fastener.

Flange Nut

1. What is a Flange Nut?

Flange nuts, also known as pad nuts, toothed nuts, hexagonal flange nuts, or flange nuts, share dimensions and specifications with hexagonal nuts. The key distinction lies in the integration of its gasket and nut, featuring anti-slip tooth patterns on the bottom. This integration increases the contact surface area between the nut and the workpiece, providing enhanced resistance against loosening compared to regular nuts and washers.

2. Application Fields

Primarily used for connecting pipes or joining pipes with equipment, the flange nut’s excellent sealing performance makes it suitable for pipe connections or workpieces requiring an expanded nut contact surface. This ensures both firmness and sealing in the connection. Its capacity to withstand high pressure and temperature contributes to preventing leakage and loosening in critical applications.

Nylon Nut

1. What is a Nylon Nut?

Nylon nuts, alternatively referred to as plastic nuts, are crafted from nylon material. Renowned for its exceptional insulation properties, non-magnetic nature, heat insulation, lightweight, high-temperature resistance, and corrosion resistance, nylon proves to be a versatile material for nut manufacturing.

2. Application Fields

Widely applied across various industrial sectors, nylon nuts are significant in the electroplating and communications industries. In contrast to conventional metal nuts, nylon nuts exhibit the advantage of not generating signal interference, such as eddy currents, making them well-suited for applications in the communications sector. Additionally, their superior resistance to acids and alkalis makes them ideal for use in environments with strong acid and alkali concentrations, as commonly encountered in the electroplating industry.

Fastening Nut

1. What is a Fastening Nut?

A fastening nut, characterized by a single-button elastic locking mechanism, is commonly employed as a supplementary nut within double-nut locking structures. Noteworthy for its lightweight construction, constituting only about 5% of the weight of standard nuts, it finds optimal utility in applications within the aerospace sector and related contexts.

2. Application Occasions

Primarily utilized as a secondary fastener in support of double-nut locking arrangements, the fastening nut is not typically employed as the primary force-bearing component. Its primary function is to secure the nut in place, preventing unintentional loosening. In application, it is initially tightened manually against the connected parts using standard nuts. Subsequently, the fastening lock nut is affixed by hand until it contacts the ordinary nut. A wrench is then utilized to further tighten the fastening nut by 60° to 90°. For loosening, it is imperative to first tighten the hexagonal nut, creating a gap between it and the locking nut, and facilitating the subsequent loosening of the fastening nut.

Cap Nut

1. What is a Cap Nut?

A cap nut, as implied by its name, is a hexagonal nut equipped with a protective cover. The primary function of the cover is to shield the exposed section of the fastener from external elements, preventing the ingress of moisture or corrosive substances. This protective measure serves an anti-rust purpose, thereby enhancing the longevity of both the nut and the connector. Cap nuts are designed in various sizes, matching different stud dimensions. In the case of extra-long studs, taller cap nuts are employed. Some cap nuts feature self-locking mechanisms, utilizing twisted threads in the hexagonal area to create a secure friction fit, preventing loosening due to vibrations.

2. Application Occasions

Cap nuts fulfill the same role as hex nuts, with a notable characteristic being that the main nut is resistant to sliding. However, it can only be tightened using tools such as an adjustable wrench, dead wrench, dual-purpose wrench (open part), or a specialized square-hole socket wrench. Commonly employed in robust and straightforward applications, such as securing tires, and front and rear axles of vehicles like cars, tricycles, and electric vehicles. They also find use in fixing the bases of road light stands and certain mechanical equipment frequently exposed to sunlight and rain.

Slotted Nut

1. What is a Slotted Nut?

A slotted nut, typically referred to as a hexagonal slotted nut, is characterized by slots machined above the hexagonal structure. Designed to be used in conjunction with bolts featuring screw holes and cotter pins, its purpose is to prevent the bolts and nuts from rotating relative to each other. This design aligns with standards like GB6178~6181. The primary function of the slotted nut is to partner with bolts possessing holes in the rods, with cotter pins inserted to prevent unintended loosening.

2. Application Occasions

Slotted nuts play a crucial role in securing the front and rear axles of vehicles. When tightening screws passing through the front and rear wheel axles to unite the frame and tires, a cotter pin is essential to prevent nut loosening. To properly secure the slotted nut, the cotter pin must pass through the center of the axle screw.

In practical applications, slotted nuts find utility in connecting various mechanical components, including bearings, gears, couplings, and more.

Wing Nut

1. What is a Wing Nut?

A wingnut is a distinctive type of nut with a head that features a protruding curvature resembling the wings of a butterfly. Beyond its aesthetic appeal, wing nuts serve important functional purposes.

Broadly categorized by processing techniques, wing nuts can be cold-headed, cast, or stamped. Additionally, based on their shape, they come in two fundamental variations: square-wing and round-wing wing nuts.

2. Application Occasions

Wing nuts offer the advantage of tool-free usage, specifically designed for convenient hand-tightening operations. The butterfly-shaped head design increases the lateral stress surface, enhancing the efficiency of hand-twisting. Primarily employed in equipment requiring frequent disassembly and maintenance, such as medical equipment, wind energy, aerospace, office equipment, petrochemical, electronic communications, and shipbuilding industries.


1. What is a T-Nut?

A T-nut is a nut shaped like a “T,” designed to prevent parts from loosening and rotating during installation. T-nuts are available in various shapes, including diamond and square variations. When T-nuts lack threads and are polished, they are referred to as slim-waisted bolts. These are particularly useful for connections subject to variable forces. In steel structures, special high-strength bolts with larger heads and altered sizes are employed.

2. Application Occasions

Known for easy installation and removal, T-nuts facilitate the positioning of parts in any orientation, significantly enhancing labor productivity. This versatility is why T-nuts find extensive use in the T-slots of various milling machines.

Reed Nut

1. What is a Reed Nut?

A reed nut is a self-locking nut composed of spring steel sheets and standard parts. This unique design enhances equipment stability and prolongs service life effectively.

2. Application Occasions

Characterized by stability under conditions of vibration, impact, and temperature variations, the reed nut boasts excellent anti-loosening and anti-vibration performance. It finds widespread application in various equipment.


The presented list encompasses commonly used nuts in the market, each with distinct performance advantages and suitable applications. Choosing the appropriate nut type involves consideration of specific needs, usage scenarios, and performance requirements. As a senior engineer, your insights on additional nuts in daily applications are welcomed—feel free to contribute to the discussion by leaving a message in the comment area. Let’s engage in further exploration and knowledge sharing!