Hex Bolt : Types of Hex Bolts, Size and

What is a Hex Bolt?

A hex bolt, also known as a hexagon head bolt or hex cap screw, is a type of fastener with a hexagonal head, typically made of steel, that is designed to be tightened or loosened with a wrench or socket tool. Hex bolts are widely used in construction, machinery, and other applications where a sturdy and reliable fastening solution is required.

Parts of a Hex Bolt:

1. Head: The top part of the bolt with a hexagonal shape, where the wrench or socket is applied for tightening or loosening.
2. Shank: The unthreaded portion of the bolt between the head and the threaded portion, providing structural support.
3. Threaded Portion: The helical ridges along the shank that grip the mating material when the bolt is tightened.
4. Tip/Point: The pointed end of the bolt that aids in the initial insertion.

How Do Hex Bolts Work?

Hex bolts work by creating a joint between two or more materials. When the hex bolt is tightened, the threaded portion engages with the corresponding threads in the mating material, creating a secure connection. The hexagonal head allows for easy application of torque using a wrench, ensuring a tight and reliable fit.

Hex bolts work by providing a secure and reliable means of fastening two or more materials together. Here is a step-by-step explanation of how hex bolts work:

1. Insertion:
   • The hex bolt is initially inserted through aligned holes in the materials to be joined.
2. Engagement:
   • The threaded portion of the hex bolt engages with the corresponding threads in the receiving material. The threads are helical ridges that wrap around the bolt’s shank.
3. Tightening:
   • A wrench or socket tool is used to turn the hexagonal head of the bolt. As the head is turned clockwise, the bolt threads into the receiving material.
4. Clamping Force:
   • As the hex bolt is tightened, the threads create a clamping force between the materials being fastened. This force pulls the materials together, creating a secure and tight connection.
5. Friction and Tension:
   • The friction between the bolt threads and the receiving threads, along with the tension generated by the tightening process, prevents the materials from coming apart unintentionally.
6. Torque Application:
   • Torque is applied to the hex bolt head, and the bolt stretches slightly due to the tension created in the shank. This stretching, often referred to as bolt tension or preload, is a critical factor in the bolted joint’s performance.
7. Securing the Joint:
   • Once the desired torque or tension is achieved, the hex bolt is secured in place. The clamping force generated by the tightened bolt keeps the materials in place and provides stability to the joint.
8. Nut or Washer (if used):
   • In some cases, a nut or washer may be used in conjunction with the hex bolt to distribute the clamping force more evenly or to provide additional support.

Hex bolts work effectively due to the combination of threaded engagement, torque application, and the resulting tension in the bolt. This method of fastening is widely used in various industries and applications where a strong and reliable connection is essential for structural integrity and stability. The hexagonal shape of the head allows for easy application of torque using common tools, making hex bolts a popular choice for fastening solutions.

Applications of Hex Bolts

Hex bolts are versatile fasteners and find applications in various industries due to their strength, reliability, and ease of use. Here are some common applications:

1. Construction:
   • Hex bolts are extensively used in construction for connecting structural elements, steel frames, and other building components. Their high strength ensures the stability and integrity of the structures.
2. Automotive Industry:
   • Hex bolts are used in the assembly of vehicles, securing components such as engines, chassis, and body parts. They play a crucial role in ensuring the structural integrity of automobiles.
3. Machinery and Equipment:
   • In manufacturing and industrial settings, hex bolts are employed to fasten machine parts and equipment. Their durability and strength make them suitable for heavy machinery applications.
4. Infrastructure Projects:
   • For infrastructure development, hex bolts are used in bridges, highways, railways, and other large-scale projects to connect and secure various components.
5. Renewable Energy Projects:
   • In the construction of wind turbines, solar panel structures, and other renewable energy installations, hex bolts are used to secure critical components in place.
6. Aerospace Industry:
   • Hex bolts are utilized in the aerospace sector for assembling aircraft components. Their strength and reliability are essential for ensuring the safety and performance of aircraft.
7. Oil and Gas Industry:
   • In the exploration and extraction of oil and gas, hex bolts are used to secure equipment and structures in challenging environments. They must withstand extreme conditions such as high pressure and corrosive environments.
8. Marine Applications:
   • In shipbuilding and maritime structures, hex bolts are employed to connect various parts of the vessel, ensuring structural integrity and durability in harsh marine conditions.
9. Electrical and Telecommunications:
   • Hex bolts are used in the installation of electrical equipment, telecommunications infrastructure, and utility poles, providing a secure connection for these critical systems.
10. Railway Systems:
    • Hex bolts are essential in the construction and maintenance of railway tracks, securing rails, sleepers, and other components to ensure the safety and reliability of the rail network.
11. Mining Industry:
    • In mining operations, hex bolts are used to secure support structures, equipment, and other components in challenging underground environments.
12. General Manufacturing:
    • Hex bolts are widely used in various manufacturing processes, securing parts and components in industries ranging from consumer goods to electronics.

Hex bolts come in various sizes and types, making them suitable for a wide range of applications across different industries. Their reliability and ease of use contribute to their widespread use in numerous construction and engineering projects.

Types of Hex Bolts:

1. 1. Fully Threaded Hex Bolts:
      • The entire length of the bolt is threaded.
      • Used in a variety of applications where a fully threaded connection is needed.
   2. Partial Threaded Hex Bolts:
      • Only a portion of the bolt is threaded, leaving an unthreaded shank.
      • Useful in situations where a combination of threaded and unthreaded sections is required.
   3. Heavy Hex Bolts:
      • These bolts have a larger head and are designed for high-strength applications.
      • Commonly used in structural and heavy-duty construction projects.
   4. Hex Tap Bolts:
      • Similar to fully threaded bolts but with a smaller hex head.
      • Suitable for applications where a low-profile or less conspicuous bolt head is desired.
   5. Hex Flange Bolts:
      • Feature a flange (wide, flat base) under the hexagonal head, providing a larger bearing surface.
      • Often used in automotive and construction applications.
   6. Structural Hex Bolts:
      • Manufactured to meet specific structural standards.
      • Commonly used in construction for connecting heavy steel structures.
   7. Hex Head Cap Screws:
      • Similar to hex bolts but typically with a shorter thread length.
      • Commonly used in precision machinery and equipment.
   8. Hex Lag Bolts:
      • Have a coarse thread and are designed for use in wood or wood-like materials.
      • Often used in woodworking and construction.
   9. Elevator Bolts:
      • Specifically designed for use in conveyor systems and elevator buckets.
      • Have a flat, countersunk head and a square neck to prevent rotation during installation.
   10. Carriage Bolts:
       • Have a round head and a square neck beneath it.
       • Used with a matching square hole in the wood to prevent rotation during assembly.
   11. Step Bolts:
       • Feature a large, flat head and a stepped shank.
       • Designed for use in structures where a flush surface is required.

   These variations cater to different needs in terms of strength, appearance, and functionality, allowing for versatile applications across various industries.

Hex Bolt Sizes:

Hex bolts come in various sizes, typically specified by their diameter, length, and thread pitch. Common unit systems for sizing include inches and millimeters.

Hex Bolt Size Chart:

A hex bolt size chart provides information about the dimensions of hex bolts, including diameter, length, and thread pitch. The chart assists in selecting the appropriate bolt for a specific application.

A hex bolt size chart provides information about the dimensions of hex bolts, including their diameter, length, and thread pitch. Hex bolts are typically measured using the Unified Thread Standard (UNC or UNF) in the United States, or the metric system in many other parts of the world. Below is a simplified hex bolt size chart:

Hex Bolt Size Chart (Inch)

Hex Bolt Size Chart (Metric)

Note: Hex bolt size charts may vary slightly depending on the specific standards used in different regions or industries. Always refer to the appropriate standards or consult with suppliers for precise specifications for your application. Additionally, there are finer thread pitches available for certain sizes, and the chart above provides a general overview.

Standards of Hex Bolts

Hex bolts adhere to various standards depending on factors such as their size, material, and the industry/application for which they are intended. Common standards for hex bolts include those set by organizations such as the American Society for Testing and Materials (ASTM) and the International Organization for Standardization (ISO). Here are a few standards commonly associated with hex bolts:

1. ASTM Standards:

   • ASTM A307: Standard Specification for Carbon Steel Bolts and Studs, 60,000 PSI Tensile Strength.
   • ASTM A325: Standard Specification for Structural Bolts, Steel, Heat Treated, 120/105 ksi Minimum Tensile Strength.
   • ASTM A490: Standard Specification for Structural Bolts, Alloy Steel, Heat Treated, 150 ksi Minimum Tensile Strength.

2. ISO Standards:

   • ISO 4014: Hexagon Head Bolts – Product Grades A and B.
   • ISO 4017: Hexagon Head Screws – Product Grades A and B.
   • ISO 4018: Hexagon Head Bolts – Product Grade C.

3. DIN Standards:

   • DIN 931: Hexagon head bolts – Partially threaded.
   • DIN 933: Hexagon head bolts – Full threaded.

4. ASME Standards:

   • ASME B18.2.1: Square, Hex, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex, Hex Flange, Lobed Head, and Lag Screws (Inch Series).

5. BS Standards:

   • BS 4190: Specification for ISO Metric Black Hexagon Bolts, Screws and Nuts.

6. JIS Standards:

   • JIS B 1180: Hexagon Head Bolts.

These standards provide specifications for the dimensions, materials, testing procedures, and other characteristics of hex bolts, ensuring that they meet specific requirements for strength, durability, and performance in various applications. It’s important to consult the appropriate standard for the specific type and grade of hex bolt required for a particular application. Additionally, regional variations may exist, and it’s essential to adhere to the standards recognized in the specific industry or geographical location.

Conclusion:

Hex bolts are essential fasteners used in diverse industries for their strength, reliability, and ease of use. Their versatility and ability to provide robust connections make them a popular choice for securing various materials together in construction, machinery, and other applications. Understanding the different types, sizes, and applications of hex bolts is crucial for selecting the right fastener for specific requirements.