
Hex head screws, also known as hex bolts, are fasteners with six-sided, hexagonal-shaped heads. They are used for heavy-duty fixing and fastening applications in a wide range of industries and applications, including construction, machinery assemblies, woodworking, engineering, and automotive. Hex head screws can be made from various materials, including steel, stainless steel, and brass, and are available in different sizes and finishes. Standard hex cap screw dimensions include a washer-facing surface under the head of the bolt, and they are manufactured with tighter tolerances compared to hex bolts.
Characteristics | Values |
---|---|
Head Shape | Hexagonal |
Head Type | Full-bearing, washer, or flanged with bonded washers |
Thread Type | Full or partial |
Materials | Zinc-plated steel, galvanized steel, organic coated steel, stainless steel, bronze, nylon, bi-metal, brass, plastic |
Use Cases | Machinery, construction, landscaping, lumber, sheet metal, automotive, electronics, appliances, woodworking |
Screw Types | Self-drilling, internal hex, combi, lag, sheet metal, zip, painted hex washer, hex tap, hex flange, hex serrated flange, hex machine, hex lag, hex head set |
Strength | Varies by grade, with Grade 9 being the strongest |
What You'll Learn
Hex bolt dimensions
Hex bolts are typically used for heavy-duty fixing and fastening applications. They are used in a variety of industries, including construction, machinery assemblies, woodworking, engineering, and automotive. Hex bolts can be used with pre-tapped holes or with nuts and can be tightened using tools like wrenches, socket sets, spanners, hex keys, and ratchet spanners.
When it comes to hex bolt dimensions, there are several factors to consider:
- Bolt Length: This refers to the length of the bolt, typically measured from the end of the bolt up to under the head. Bolt lengths can vary depending on the specific application and are usually available in standard sizes.
- Thread Size: The thread size of a hex bolt refers to the size of the thread, commonly measured using ISO metric or M-style measurements. The ISO metric thread size system uses the letter "M" followed by a number to indicate the outer diameter of the thread in millimetres. For example, an M8 thread size indicates an outer diameter of 8 millimetres.
- Thread Pitch: Thread pitch refers to the number of threads per inch. Finer bolts have a higher thread pitch, which means they have more threads per inch.
- Width Across Flats (WAF): This dimension refers to the distance across the flats of the hexagonal head. The WAF can vary depending on the bolt standard and size. For example, according to DIN 931/ISO 4014, the WAF for an M10 bolt is 16 millimetres, while for an M22 bolt, the WAF is 34 millimetres.
It is important to note that hex bolts and hex cap screws are different. Hex cap screws are more precise and have tighter tolerances. They also feature a washer facing under the head of the bolt. While the dimensional measurements of different grades of hex cap screws may be identical, the materials used can vary.
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Hex cap screw dimensions
Hex cap screws are commonly used in construction and machine assembly. They are made to universal specifications, meaning that their dimensions are standardised across the globe.
The length of a cap screw is measured from the underhead bearing surface to the extreme end of the screw. The standard dimensions of a hex cap screw include the basic product diameter, the width across corners, the transition thread length, and the nominal screw length.
For example, a Grade-5 HEX CAP Screw made from medium carbon steel has a Rockwell hardness of C25-C34 for 1/4 through 1 in. diameter, all lengths. The same screw has a minimum tensile strength of 85,000 psi for the same specifications.
A Grade-8 HEX CAP Screw, on the other hand, is made from medium carbon alloy steel and heat-treated. It has a Rockwell hardness of C33-C39 for 1/4 through 1-1/2 in. diameter, all lengths. This screw has a minimum tensile strength of 120,000 psi for the same specifications.
It is important to note that while hex cap screws and hex bolts may look similar, they are not interchangeable. Hex bolts are "less precise" and, therefore, cheaper than hex cap screws. Hex cap screws are manufactured with a higher level of precision and have a washer facing under the head of the bolt.
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Hex bolt uses
Hex bolts, also known as hex cap screws, are large bolts with a six-sided head used to fasten wood to wood or metal to wood. They are commonly used in construction and machine assembly. Hex bolts have small threads and a smooth shank, and they may be made of plain steel for interior projects or stainless steel/galvanized for exterior use.
Hex bolts are tightened using a wrench or a socket, with one tool holding the bolt head and another tightening the nut. They are available in various materials, including stainless steel, which offers excellent resistance to corrosion and is suitable for marine or chloride environments. Hex bolts can also be made from steel, which is the most commonly used material for fasteners, accounting for 90% or more.
The distinction between a bolt and a screw is not always clear-cut, and the terms are often used interchangeably. However, the academic distinction is based on their intended purpose. Bolts are designed to pass through an unthreaded hole in a component and be fastened with a nut, while screws are used in components that contain their own thread or cut their own internal thread.
Hex bolts come in different varieties, such as anchor bolts, which are designed to attach objects to concrete, and elevator bolts, which feature a large flat head used in conveyor system setups.
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Hex bolt threading
Hex bolts are threaded bolts with hexagonal heads. They are the most common fasteners used in construction. They are available in two varieties: fully threaded and partially threaded.
Fully Threaded Hex Bolts
These bolts are threaded from the end of the bolt right up to the head. They are suitable for heavy-duty fastening applications and are best used with pre-threaded holes. When installed properly, they are designed to spread the pressure across the full length of the bolt, providing greater strength than partially threaded bolts.
Partially Threaded Hex Bolts
Partially threaded hex bolts are threaded from partway down the bolt's length to the end, with an unthreaded "shank" or "grip length" joining the threaded portion to the head. This unthreaded section provides greater resistance and strength against sideways forces since it is stronger than the threaded area.
The threading of a hex bolt, also known as the screw thread, is the helical structure that comprises the main body of the bolt. It uses rotational force to drive the bolt into place, providing easier entrance and exit into the material while also offering added grip.
Hex Bolt Thread Pitch
The thread pitch of a hex bolt refers to the number of threads per inch. The finer the bolt, the more threads per inch, and the higher the thread pitch. For example, a thread pitch of 1/13" indicates that there are 13 threads per inch.
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Hex bolt materials
Hex bolts are available in a variety of materials, each with its own unique properties and applications. The choice of material depends on the specific requirements of the project, such as the amount of stress the bolt needs to withstand, the environment it will be used in, and the level of corrosion resistance needed.
One common material for hex bolts is stainless steel. Stainless steel bolts are often chosen because they are corrosion-resistant and do not require any additional coating. They are suitable for high-temperature applications and can be used in freshwater marine environments, but they are less suitable for saltwater environments.
Carbon steel bolts are another popular option for hex bolts. These bolts are typically zinc-plated to enhance their corrosion resistance. Carbon steel bolts are available in different grades, such as low to medium carbon steel, which is used for standard household applications, and medium carbon alloy steel, which is used for high-strength structural applications.
Alloy steel bolts are designed to withstand extremely high amounts of pressure and are commonly used in high-stress environments. To protect against corrosion, alloy steel bolts are typically coated with cadmium or zinc plating.
For applications that require high tensile bolting, such as boilers, pressure vessels, and pipeline flanges, ASTM A193 Grade B16 hex bolts are a suitable option. These bolts are manufactured to withstand high temperatures and pressures and are available in both metric and imperial sizes.
In addition to the standard materials mentioned above, hex bolts can also be made from other specialty materials, such as duplex stainless steel, nickel-aluminium bronze, and silicon aluminium bronze. The specific material chosen depends on the unique requirements of the application, as each material offers different strengths and corrosion resistance properties.
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Frequently asked questions
Hex head cap screws are graded based on their material and tensile strength. Grades 5 and 8 are made from medium carbon steel and medium carbon alloy steel, respectively.
Hex head screws are commonly used in construction and machine assembly. They can also be used in high-temperature environments, such as automotive parts assembly, and in marine and coastal operations due to their anti-corrosion properties.
The dimensions of hex head screw standards include the nominal or basic product diameter, width across flats, width across corners, and length. These dimensions can vary depending on the specific standard and application.
The performance and mechanical requirements of hex head screw standards include tensile strength, corrosion resistance, and temperature resistance. For example, Grade 5 hex cap screws have greater tensile strength than Grade 2, while Grade 8 has even higher tensile strength and is designed for high-stress applications.
Hex head screw standards can be found in publications such as ASME B18.2.1-1996 and SAE J429 1985. These standards specify the dimensions, materials, and mechanical properties of hex head screws.