Shear bolts are a type of security fastener that are used to join two pieces of metal together in a permanent and tamper-proof way. Unlike regular bolts, which can be loosened or removed using a nut or a wrench, shear bolts are designed to break off when a certain amount of force is applied. This makes them ideal for applications where a joint must withstand high loads without falling apart or being tampered with.
In here, we will explain what shear bolts are, how they work, what types of shear bolts are available, what are their advantages and disadvantages, and where they are commonly used.
How do Shear Bolts Work?
Shear bolts consist of two parts: a threaded shaft and a hexagonal head. The head has a collar that fits over the shaft and acts as a drive for tightening the bolt. The head and the collar are connected by a thin section that is weaker than the rest of the bolt.
When the bolt is tightened using a standard spanner or socket tool, the force applied reaches a certain point where the thin section snaps off. This leaves behind a smooth or domed head that has no drive or means of removal. The bolt is now permanently secured and can only be removed by drilling or cutting.
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The shear-off torque, or the force required to break off the head, depends on the size and material of the bolt. Typically, shear bolts are made of stainless steel or carbon steel and have diameters ranging from 1/4 inch to 3/4 inch.
Types of Shear Bolts
There are different types of shear bolts available for different applications and preferences. Some of the common types are:
- Dome head shear bolts: These have a round or dome-shaped head that blends in with the surface of the metal. They are suitable for applications where aesthetics are important or where there is no space for protruding heads.
- Countersunk head shear bolts: These have a flat or tapered head that sits flush with the surface of the metal. They are suitable for applications where there is a risk of snagging or interference from protruding heads.
- Cap head shear bolts: These have a cylindrical or hexagonal head that protrudes slightly from the surface of the metal. They are suitable for applications where extra grip or torque is required or where there is no risk of snagging or interference from protruding heads.
- Button head shear bolts: These have a low-profile or mushroom-shaped head that protrudes slightly from the surface of the metal. They are suitable for applications where aesthetics are important or where there is limited space for protruding heads.
- Slim head shear bolts: These have a thin or narrow head that protrudes slightly from the surface of the metal. They are suitable for applications where there is limited space for protruding heads or where extra security is required.
- Socket shear bolts: These have an internal hexagonal drive that requires a special tool to tighten them. They are suitable for applications where extra security is required or where there is no risk of snagging or interference from protruding heads.
- Shear barrel nuts: These are similar to shear bolts but have a threaded hole instead of a shaft. They are used in conjunction with regular bolts to create a secure joint. They are suitable for applications where extra strength or alignment is required.
Advantages and Disadvantages of Shear Bolts
Shear bolts have several advantages and disadvantages compared to regular bolts. Some of them are:
Advantages
- Security: Shear bolts provide a high level of security as they cannot be easily removed or tampered with once installed. They prevent unauthorized access, theft, vandalism, sabotage, or accidental loosening of joints.
- Durability: Shear bolts are made of strong and corrosion-resistant materials that can withstand high loads and harsh environments. They do not require maintenance or replacement unless damaged.
- Simplicity: Shear bolts are easy to install using standard tools and do not require special skills or training. They do not require nuts, washers, lock washers, or other accessories to secure them.
- Versatility: Shear bolts come in various sizes, shapes, and materials to suit different applications and preferences. They can be used on various types of metals and surfaces.
Disadvantages
- Permanence: Shear bolts are permanent and irreversible once installed. They cannot be reused or adjusted if needed. They can only be removed by drilling or cutting, which can damage the metal or the bolt itself.
- Cost: Shear bolts are more expensive than regular bolts due to their specialized design and material. They also require more care and precision during installation to avoid breaking them prematurely.
- Availability: Shear bolts are not as widely available as regular bolts and may require special ordering or sourcing. They may also have limited compatibility with other fasteners or tools.
Where are Shear Bolts Used?
Shear bolts are used in various industries and applications where robust permanent security fasteners are required. Some of the common examples are:
- Prisons: Shear bolts are used to secure doors, windows, bars, fences, gates, and other fixtures in prisons and detention centers. They prevent inmates from escaping or causing damage.
- Banks: Shear bolts are used to secure safes, vaults, cash machines, and other valuables in banks and financial institutions. They prevent thieves from breaking in or stealing money.
- Automotive: Shear bolts are used to secure wheels, tires, engines, transmissions, and other components in cars, trucks, buses, and other vehicles. They prevent theft, vandalism, or tampering.
- MOD and Aerospace: Shear bolts are used to secure weapons, missiles, rockets, satellites, and other equipment in the military and aerospace sectors. They prevent sabotage, espionage, or accidental launch.
- Solar Panels: Shear bolts are used to secure solar panels and frames on roofs, walls, or ground mounts. They prevent theft, vandalism, or damage from wind or weather.
What Is The Difference Between A Shear Bolt And A Breakaway Bolt?
A shear bolt is a type of bolt that is designed to break off when a certain amount of force is applied, leaving behind a smooth or domed head that cannot be removed.
A breakaway bolt is a type of bolt that has a hollow threaded shank, which is designed to break away upon impact.
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The main difference between them is that a shear bolt breaks due to tension or pressure, while a breakaway bolt breaks due to impact. Shear bolts are often used in applications where safety is a concern, such as in load-bearing structures or in machinery.
Breakaway bolts are typically used to fasten fire hydrants, so they will break away when hit by a car. Also used in aircraft to reduce weight.
How Do I Choose Between a Shear Bolt And a Breakaway Bolt?
The choice between a shear bolt and a breakaway bolt depends on the type of force and the purpose of the connection.
A shear bolt is suitable for applications where the bolt needs to break due to tension or pressure, such as in load-bearing structures or in machinery.
A breakaway bolt is suitable for applications where the bolt needs to break due to impact, such as in fire hydrants or in aircraft.
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Some other factors to consider are the cost, availability, and re usability of the bolts. Shear bolts are usually more expensive, less available, and not reusable compared to regular bolts.
Conclusion
Shear bolts are a type of security fastener that are designed to break off when tightened, leaving behind a smooth or domed head that cannot be removed. They provide a permanent and tamper-proof solution for joining two pieces of metal together in a secure way. They have various advantages and disadvantages compared to regular bolts and are used in various industries and applications where robust permanent security fasteners are required.
If you are looking for shear bolts for your project or business, you can find a wide range of shear bolts from Fastenright Ltd, a leading supplier of security fasteners. You can also order custom-made shear bolts to suit your specific requirements and drawings.
