Nut vs Bolt: Types, and Differences with Screws and Rivets - BOYI

23 Jun.,2025

 

Nut vs Bolt: Types, and Differences with Screws and Rivets - BOYI

Nuts and bolts are common fasteners in the manufacturing industry, serving the purpose of mechanically connecting two or more components together. For instance, when installing equipment, screws are used to secure various objects. Many people are not clear about the differences between bolts and nuts. Some believe that bolts are nuts, and nuts are bolts. However, this misconception is incorrect. In this CNC machining guide, we will delve into the distinctions between bolts and nuts, as well as the types they come in.

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What is a Nut?

A nut is a fastening device, typically made of metal, featuring a square or hexagonal block with a central hole that has internal threads. These threads fit onto the male threads of a corresponding bolt or screw, creating a secure connection. Nuts are essential in fastening machine and structural components. Variations include standard square and hexagonal nuts, as well as specialized types like slotted nuts and locknuts that prevent loosening.

Advantages and Disadvantages of Nuts

Types of Nut

There is a wide variety of nut types, each with its specific uses and advantages. Some of the most common types of nuts include:

1.Acorn Nuts

Acorn nuts, as the name suggests, are nuts with caps, named for the acorn-shaped cap at the top. Their primary purpose is to prevent foreign particles and moisture from infiltrating the interior, thus avoiding corrosion and rust. They also serve to minimize the risk of skin and clothing catching on sharp edges. Therefore, these nuts are often used in industrial machinery in areas where contact with the human body is frequent, reducing the risk of injury to personnel.

2.Weld Nuts

Weld nuts are nuts designed to be welded onto another component. They are typically made of weldable materials and have a thicker structure to accommodate the welding process. Weld nuts create a strong connection by fusing the two separate pieces into one solid unit through high temperatures.

Weld nuts find widespread use in applications requiring high-strength connections, such as in construction, bridges, vehicle manufacturing, and other fields. They are welded into place to provide sturdy support and connection at their respective positions.

3.Hex Nuts

Hex nuts are named for their hexagonal shape, featuring six equal sides and angles. This design allows them to be easily tightened or loosened using tools such as wrenches or screwdrivers. Hex nuts are suitable for fastening most mechanical components and equipment, capable of withstanding high pressures without deformation or damage.

4.Wing Nuts

Wing nuts feature a wing-shaped structure with wings on each side of the nut, allowing them to be easily rotated by hand without the need for tools. This makes them particularly suitable for use on equipment that requires frequent disassembly or fastening. Their design enables quick and convenient operation.

Wing nuts are commonly used in mechanical equipment, electrical equipment, transportation vehicles, and other applications where frequent tightening or loosening of nuts is necessary. They are the perfect solution for situations requiring frequent adjustment or removal of nuts.

5.Barrel Nuts

Barrel nuts, also known as sex bolts or Chicago screws, are made of steel and feature extremely thin bolt heads and metal parts. Their advantage lies in not requiring flanges to be machined or forged on the receiving component, thus reducing their weight.

6.Jam Nuts

Jam nuts are highly practical fasteners, typically hexagonal in shape and half the size of regular nuts. They come in various designs and structures, including but not limited to friction locking, mechanical locking, rivet locking, and structural locking methods.

In mechanical and engineering applications, the problem of nuts loosening due to vibration or impact is often encountered. The introduction of jam nuts effectively addresses this issue. For example, In automotive fasteners, jam nuts are primarily used as fasteners for critical components such as automotive suspension, engines, and transmissions to prevent loosening caused by vibration and impact.

7.Lock Nuts

Lock nuts utilize friction between the nut and bolt to self-lock, ensuring the stability of the connection. In some critical applications, additional anti-loosening measures may be taken to ensure the reliability of nut locking. Refer to the “jam nuts” mentioned above.

Lock nuts are widely used in industries such as machinery to secure threaded pipe fittings or other components, ensuring stable and safe connections.

8.Flange Nuts

Flange nuts, also known as flanged nuts, washer-faced nuts, serrated flange nuts, or hex flange nuts, feature a wide flange at one end, which effectively acts as an integrated washer. When the nut is tightened, this flange distributes pressure evenly across the secured component, reducing the risk of damage due to excessive pressure and increasing the stability of the entire connection.

Please watch the following YouTube video to learn how your nuts and bolts are made.

What is a Bolts?

A bolt is a mechanical fastener typically used with a nut to connect two or more parts. It consists of a head and a cylindrical body with screw threads along part of its length. Bolted joints can be easily disassembled and reassembled, making bolts a preferred choice in mass-produced items and steel structures. Washers are often used alongside bolts to prevent loosening and distribute pressure.

Advantages and Disadvantages of Bolt

Types of Bolts

There are various types of bolts that can be classified according to different standards and requirements. The following are some common types of bolts:

1.Anchor Bolts

Anchor bolts are commonly used in the construction industry. They utilize the structure of the bolt itself, combined with special components, to expand and anchor in concrete foundations within bolt holes. This type of bolt is convenient to install on-site and can immediately bear loads once installed. Moreover, they can be disassembled and reused if necessary, making them popular among professionals and DIY enthusiasts alike.

2.Carriage Bolts

Carriage bolts consist of a head and a cylindrical shaft with external threads, making them fasteners that require use with nuts to securely connect two components with through-holes. Their heads are often hexagonal and relatively large, with a rounded shape and no designs such as cross-slots or internal hexagons. This design not only facilitates installation but also serves as a deterrent against theft during the connection process.

3.Blind Bolts

Blind bolts are a special type of bolt characterized by their non-through-hole design. They typically feature internal hexagon and internal hexagon with grip slot structures, facilitating installation using hexagon wrenches or socket heads. This design makes blind bolts particularly useful in situations where tightening can only be done from one side.

Blind bolts exhibit high strength. For example, a blind bolt with an M20 specification can have a shear load-carrying capacity design value of up to 54.5 kN (single shear surface), and the tensile load-carrying capacity design value varies depending on the type of blind bolt but generally remains high. This strength ensures that blind bolts can provide stable and reliable connections in various applications.

4.U-Bolts

U-bolts, also known as horse bolts, are named for their unique U-shaped structure. These bolts are non-standard components. They feature threads at both ends of the U shape, which can be combined with nuts to achieve fastening. U-bolts are primarily used for securing cylindrical objects such as pipes or flat objects like vehicle leaf springs.

5.Eye Bolts

Eye bolt is a type of bolt with a lifting eye on the head, characterized by a longer shaft and fewer threads. It consists of three parts: the lifting eye, nut, and bolt. Usually used for lifting or hanging heavy objects, such as outdoor fences, tower cranes, and other scenarios.
During installation, the lifting eye bolts must be installed vertically on the plane of the workpiece, the joint surface should be flat and tight, and adjusted to the stretching direction to avoid contact with sharp edges. Its test load is 2.5 times the working load, and fatigue tests are conducted at 1.5 times the working load.

6.Hex Bolts

Hex bolts are one of the most commonly used types of bolts. Their surfaces are hexagonal in shape, allowing for rotation using tools such as wrenches to apply the necessary force for fastening. Regarding the threaded portion, hex bolts can be fully threaded or partially threaded. They are suitable for connecting various mechanical equipment and structures.

7.Flange Bolts

Flange bolts primarily consist of three parts: a hexagonal head, a flange (which includes a washer and is integrated with the hexagon below), and a shaft (a cylindrical body with external threads). The flange serves as a washer, distributing the load and providing a larger “support area to stress area ratio” for the bolt.

The working principle of flange bolts mainly relies on the mutual engagement of the threads. When the nut is rotated, the threads between the bolt and the nut interlock, causing the bolt to move forward or backward, achieving the fastening effect. Compared to regular bolts, flange bolts have wider heads and usually have expanded tails, making them more sturdy and secure.

Flange bolts are widely used in scenarios requiring the bearing of heavy loads and higher safety, such as automotive engines and heavy machinery products.

How to Choose the Appropriate Nut for Your Bolt?

Selecting the appropriate nut for a bolt is a process that requires considering multiple factors. Below are some key steps and factors to consider:

1.Match Thread Specifications

Ensure that the chosen nut’s thread specifications match those of the bolt completely. This includes parameters such as nominal diameter, pitch, and thread count. For example, an M6 bolt should correspond to an M6 nut. If the specifications don’t match, the nut won’t properly install on the bolt, affecting the fastening effect.

For more thread specifications and sizes, please refer to the following article: Thread Size Chart

2.Size and Shape

Choose the appropriate nut size and shape based on the usage scenario and requirements. For instance, the selection of head type may involve factors such as anti-tamper performance, appearance, and stability. If a stable and secure nut is needed, consider using a prevailing torque nut or a nut with washers.

3.Determine Required Strength

Select the nut material and grade based on the strength requirements of the application. For instance, for applications requiring high loads, opt for high-strength nuts.

4.Consider Environmental Conditions

If the nut will be used in damp, corrosive, or high-temperature environments, choose a nut with corresponding corrosion resistance and high-temperature characteristics. Stainless steel nuts are typically suitable for these special environments.

5.Choose the Appropriate Nut Type

Select the appropriate nut type based on specific needs. For instance, if better anti-tamper performance is required, consider using a hex flange nut; if higher strength is needed, opt for a prevailing torque nut, etc.

Common Bolt and Nut Materials

The commonly used materials for bolts and nuts include:

  1. Carbon steel
  2. Stainless steel
  3. Alloy steel
  4. Aluminum alloy
  5. Titanium alloy
  6. Brass
  7. Polymers, such as nylon

What is the Difference Between Nuts and Bolts?

A bolt consists of a head and a cylindrical body with screw threads along part of its length. It is typically used with a nut, which is the female counterpart with internal threads that match the bolt’s threads. Washers are often added between the bolt head or nut and the surfaces they connect to prevent loosening and distribute pressure evenly.

Nut vs bolt chart

Contact us to discuss your requirements of Square Nut Supplier. Our experienced sales team can help you identify the options that best suit your needs.

How Are Nuts And Bolts Held Together?

Nuts and bolts are held together primarily through threaded engagement. The external threads on the bolt mesh with the internal threads of the nut, creating a tight connection that resists pulling apart. As the nut is tightened, it applies compressive force, squeezing the parts together. Friction between the threads helps prevent loosening, while the slight stretching of the bolt under tension further enhances the clamping force. In applications prone to vibration or movement, additional locking mechanisms like nylon-insert lock nuts or mechanical washers are used to maintain tightness and prevent unintended loosening over time.

Strength Comparison: Nut vs. Bolt

In engineering, the strength of a joint between a nut and a bolt is crucially important. When assembling a joint, torque is applied to achieve a proper clamp load, ensuring the components are securely fastened. If too much torque is applied:

  1. Bolt Strength: If the bolt is weaker, it may stretch or even break before reaching the intended torque, signaling a problem during assembly.
  2. Nut or Tapped Hole Strength: If the nut or tapped hole is weaker, it may yield or fail under excessive torque, leading to thread damage like galling or seizing. This can compromise the joint’s integrity and potentially lead to failure under service loads.

To ensure a reliable joint, it is recommended that the nut (or the threaded member) be stronger than the bolt.

Difference Between Bolts, Nuts, Screws, and Rivets

For more information about rivets, please read this article: What is a Rivet

Why Use Washers With Nuts and Bolts?

Using washers with nuts and bolts ensures even distribution of load across the fastened surfaces, protecting them from damage and preventing loosening over time. Washers also help create a secure clamping force, enhancing the integrity of the connection by spreading the load over a larger area. In specific cases, washers may be placed on the bolt side to facilitate installation or removal.

Summary

In summary, nuts and bolts have their own characteristics in function, structure, and use, and they work together to achieve the fastening of mechanical connectors. In practical applications, it is necessary to select appropriate types, specifications, and materials of nuts and bolts based on specific connection requirements and environmental conditions.

Boyi, as a professional provider of CNC machining services, possesses advanced equipment and a skilled team capable of delivering high-quality, high-precision fasteners to customers. Feel free to contact Boyi anytime for detailed consultations and expert advice.

FAQ

Comprehensive Guide to Locking Nut: Types, Applications

What is the Locking Nut?

The locking nut, also known as a: nut with lock, locknut, lock nut, self-locking nut, stiff nut or prevailing torque nut, is a specially designed nut that is a fastener that prevents loosening or backing out due to vibration or torque.

Unlike regular nuts, which may loosen over time, nut with lock offer added security and reliability for a more secure hold.

Compared with standard nuts, self-locking nut have the following advantages:

  • Strong anti-loosening performance: Due to the existence of the locking mechanism, self-locking nut are not easy to loosen under vibration conditions
  • Widely used: Can be used in various occasions that require high safety and stability, such as aerospace, railways, mechanical equipment, and other high-vibration environments

However, nut with lock also has some disadvantages:

  • Higher cost: Due to the complex structural design, the manufacturing cost is usually higher than that of ordinary nuts
  • Difficult to disassemble: Due to the existence of the locking mechanism, locking nuts require greater force when disassembling, and sometimes they cannot even be reused

How does a Locking Nut Work?

Locking nuts are usually divided into two different locking principles:

  1. One is to use the elastic deformation of the metal itself to produce locking effect, such as nylon lock nut, which embed nylon rings in the nut to increase friction and thus lock.
  2. The other is through the design of special threads or structures to achieve self-locking, such as all-metal locking nuts, through the threads of the self-locking performance to enhance the anti-loosening ability of the nut.

What are the types of Nut with Lock?

Here’s a detailed look at the different types of lockable nuts, their unique features, and their specific applications:

1. Nylon Insert Nut with Lock( Self locking nut )

Mechanism:

  • These nuts feature a nylon collar insert that creates friction between the nut and the bolt, preventing loosening.
  • The nylon insert deforms over the threads, increasing resistance to vibration and movement.
  • Not recommended for multiple uses, as the nylon insert may wear out after the first use, reducing its effectiveness.

Advantages:

  • Effective for reducing loosening due to vibration.
  • Suitable for a wide range of applications.

Applications:

  • Automotive industry
  • Machinery and equipment
  • General industrial use

2. Keps K-Lock Nuts

Mechanism:

  • These nuts have an attached free-spinning washer that provides additional friction and locking action when tightened.
  • The washer helps distribute the load and prevents loosening due to vibration.

Advantages:

  • Integrated washer simplifies assembly and provides consistent locking force.
  • Suitable for a wide range of applications where vibration is a concern.
  • Reusable, but the attached washer may wear out over time, reducing its effectiveness.

Applications:

  • Electronics
  • Machinery and equipment
  • Automotive applications

3. Stover Nuts with Lock

Mechanism:

  • Also known as top locking nuts, Stover nuts have a conical top that creates a locking action through friction when tightened onto the bolt.
  • The deformed threads create resistance against loosening.

Advantages:

  • High strength and reliability.
  • Suitable for high-vibration environments and heavy-duty applications.
  • Typically reusable, but their effectiveness may decrease slightly with each reuse due to wear on the threads.

Applications:

  • Construction equipment
  • Heavy machinery
  • Automotive industry

4. Serrated Flange Locking Nuts

Mechanism:

  • These nuts have serrations on the flange that dig into the mating surface when tightened.
  • The serrations increase the friction between the nut and the surface, preventing loosening.

Advantages:

  • Effective in distributing the load over a larger area, reducing the risk of damage to the mating surface.
  • Provides additional locking force without the need for a separate washer.
  • Reusable, but the effectiveness of the serrations may diminish with repeated use.

Applications:

  • Applications where the bolt or screw is installed against a flat surface
  • Structural assemblies

5. Locking Wheel Nuts (Locking Lug Nuts)

Mechanism:

  • These nuts are designed specifically for securing wheels on vehicles.
  • Often feature a unique pattern that requires a special key to remove, preventing theft.

Advantages:

  • High security for vehicle wheels.
  • Prevents unauthorized wheel removal.
  • Generally reusable, but the locking mechanism’s effectiveness should be checked periodically.

Applications:

  • Automotive industry

6. Jam Nuts (also called half lock nut)

Mechanism:

  • These are thin nuts used in conjunction with a standard nut to lock the assembly in place.
  • The jam nut is tightened against the standard nut, creating a locking action.

Advantages:

  • Simple and cost-effective locking solution.
  • Easy to install and remove.
  • Reusable, with minimal wear over multiple uses.

Applications:

  • General mechanical applications
  • Light-duty applications

7. Castellated Nuts (Castle nut) and Slotted Nuts

Mechanism:

  • Castellated Nuts: These nuts have slots (or castellations) cut into one end. A cotter pin is inserted through a hole in the bolt and the slots in the nut to prevent rotation.
  • Slotted Nuts: Similar to castellated nuts, but with fewer and larger slots. They also use a cotter pin for locking.

Advantages:

  • Extremely secure locking mechanism that prevents the nut from loosening, even under severe vibrations and loads.
  • Suitable for applications where regular inspection and maintenance are possible.
  • Reusable, provided the cotter pin or other locking device is replaced each time the nut is reused.

Applications:

  • Automotive and machinery where safety is crucial.
  • Heavy equipment and machinery assemblies.
  • Applications where a high degree of security against loosening is required.

What are the Benefits of Using Locking Nuts?

  • Vibration Resistance: Locking nuts are specifically designed to resist the effects of vibration and dynamic loads, ensuring a secure assembly over time.
  • Improved Safety: By preventing accidental loosening, nut locking contribute to the safety and reliability of mechanical systems.
  • Durability: High-quality locking nuts can withstand harsh environmental conditions, including extreme temperatures and exposure to chemicals.
  • Reusability: While some lock nuts, such as nylon insert lock nuts, may degrade with repeated use, many types of lock nuts, can be reused multiple times without losing their effectiveness.

How to Choose the Right Locking Nut?

When selecting a locking nut for your application, consider the following factors:

  • Application Environment: Determine if the nut will be exposed to high temperatures, chemicals, or extreme vibrations.
  • Load Requirements: Ensure the nut can handle the mechanical loads and stresses of your application.
  • Material Compatibility: Choose a locking nut material that is compatible with the bolts or screws and the overall assembly.
  • Reusability Needs: Decide if the nut needs to be reused multiple times or if a single-use solution is acceptable.

FAQs:

Q1: What materials are locking nuts made from? A: Locking nuts are typically made from stainless steel, carbon steel, or alloy steel. Some may have coatings for additional corrosion resistance.

For more information, please visit Hex Bolt Supplier.