A blind bolt fastener is a structural fastener that offers greater strength and adaptability than a weld or rivet. The term “blind” bolt comes from the fact that you can only see one side of the workpiece when you apply these fasteners. Using pre-drilled holes, you can fasten two pieces together without having to access the other side.
Blind bolt fasteners are among the strongest and most versatile fasteners in use today. For construction, manufacturing, transportation, and other industries, blind bolts have proven themselves to be permanent and secure, and they are ideal for applications where a weld, rivet, or some other kind of joint just won’t do.
In fact, blind bolt fasteners have become so popular that they now come in a variety of sizes, strengths, and configurations for every conceivable application. That’s why it is important to know about the types of blind bolts currently available, the vendors who make them, and their potential applications. Blind bolt fasteners have been used for more than a century and have proven themselves to be extremely valuable when you need to connect two workpieces but only have access to one side. Blind bolts also have the advantage of added tensile strength, and they are tamper-resistant. They are known to make clean, lasting joints.
Most blind bolt fasteners consist of a steel pin, a sleeve, and a collar. The blind bolt is inserted into a pre-drilled hole and driven home using a blind bolt tool, similar to a riveter. The collar forms a strong bond as the expander collapses to hold the blind side firm, and the collar creates a seal. Blind bolts are solid and easy to install without any training. They are ideal for applications such as connecting box sections, girder cavities, or any application that needs a firm connection with superior strength.
For even greater versatility, blind bolt fasteners come in different sizes, widths, and materials, including steel, aluminum, and plastic. However, you can’t use just any blind bolt for any job. Even though blind bolts tend to make stronger joints, they can still fail if you use the wrong bolt for the application.
With all the fasteners currently available on the market, choosing the right one for the task at hand can be a challenge. There are times when you need a heavy-duty, industrial-strength fastener where welding won’t work and regular fasteners just aren’t up to the job. That’s when it makes sense to use structural steel blind bolts for a lasting and secure solution.
Structural steel blind bolts are ideal for big jobs, such as construction, railway, mining, containers, renewable energy, and manufacturing of heavy machinery. The added strength of structural steel creates a lasting joint that won’t wear out over time. More importantly, structural steel blind bolts are designed to withstand long periods of heavy vibrations, which are common with manufacturing equipment, transportation systems, and so on.
Like all blind bolts, structural steel blind bolts are designed with a stem and a sleeve or collar. The bolt is inserted in a pre-drilled hole and installed using a tool that pulls the stem into the sleeve or collar, expanding the sleeve on the blind side to create a flare that makes a secure joint. The great thing about blind bolts is that they are easy to install using simple tools that require little or no training.
When choosing a fastener such as a structural steel bolt, it is important to ensure it is an exact fit to guarantee a secure joint. You need to match the bolt to the size of the hole and make sure the length grip range is sufficient to join the materials. To ensure you have the right fastener for the task, we recommend using a range chart supplied by the manufacturer. Structural steel blind bolts also come in different strengths, so you should use the bolt maker’s performance chart to make sure you match the strength of the bolt to the task.
Versatile and Tamper-Proof
What makes blind bolts so versatile is that they are easy to install and stronger than rivets. They are also easy to inspect to ensure the bolt is properly installed. The strength of the blind bolt fastener is determined by its length from the underhead surface to the first thread of the shaft. The grip is the thickness of the material being joined. When properly installed, blind bolts are quite tamper-proof, making them ideal for public buildings and transit systems. Additionally, they can be cleanly removed using the right tool without damaging the hole or the material.
Because of their durability and resistance to vibration, blind bolts are finding their way into a wide range of applications, including automotive manufacturing, construction, shipping, public transit, rail, and mining—any environment where the material bindings need to stand up to heavy use. They are also ideal for public buildings and other applications where vandalism may be a problem.
Two Winning Blind Bolt Makers: Avdel and Huck
There are thousands of blind bolts on the market, so you need to choose the right blind bolt fastener for the job. Here are two of our most popular blind bolt fasteners from two leading manufacturers:
Avdel’s Avbolt® Blind Bolts
For heavy-duty applications such as construction, transportation, mining, or bridge-building, the Avdvel Avbolt was designed with a stem made from steel and black oxide and a carbon-steel, zinc-plated collar. The Avbolt is available in diameters from 3/16 inches to 5/8 inches and outperforms rivets and welds. Avbolts also have a locking feature that ensures a permanent and tamper-proof joint that resists vibration.
The Avdel Avbolt® blind bolt is designed to deliver extra strength and secure assembly. These blind bolts are manufactured to specific tolerances for consistency in assembly and performance. They are more permanent than welds and will not loosen when properly installed.
The Avbolt can be installed using a handheld, high-performance tool engineered for durability and fast, consistent installation in seconds. Tools require no special training and many are battery-operated so they can be used anywhere. Another advantage is the Avbolt’s versatility. It is designed with wide grip capabilities so it suits joining materials with different thicknesses. These blind bolts are considered to be high performers with high tensile strength and durability usually only found with non-blind lockbolts, yet they are fast and easy to install.
Huck BOM® Blind Bolts
Huck is one of the most trusted names in blind bolts, and the Huck BOM (blind, oversized, mechanically locked) is one of the strongest fasteners available. Its push-and-pull installation design makes it perfect for applications that normally require welded or threaded fasteners, such as military vehicles, rail cars, and auto suspensions. The Huck BOM requires no special skill to install and has a high joint tightness, making it tamper-resistant and hard to remove. It also has a mechanical lock feature to create vibration-resistant joints. In fact, the BOM is so tough that one Huck BOM bolt can do the work of four conventional fasteners.
The Huck BOM is easy to install—anyone can learn how to do it in 10 minutes. No skilled labor is required, and installations are extremely accurate, so there is no room for human error. It is also compatible with tools you likely already have, so no special equipment is required. Huck's BOM installation systems and tools are designed to offer the highest levels of ergonomics, productivity, and long life. The Huck line of BOM installation tooling reflects the same level of innovation and quality as its advanced fasteners. Whether it’s a Huck hydraulic tool employed in high-volume installation of large diameter BOMs or a smaller pneudraulic model used to install smaller diameter sizes, you can count on these tools to deliver the industry’s best value.
If you’re not sure which structural steel blind bolt is the best option for your next job, our team of experts is always available to answer your questions. We are committed to recommending the best tool for your job and ensuring you get a high-quality product.
Best Options for Aerospace Blind Bolts
Cherry Aerospace is a well-known global leader in the design and manufacture of fastening systems for the aerospace industry, and you can find a large selection of CherryMAX® rivets at Bay Supply. The brand is synonymous with quality and dates back to 1940 when the Cherry Rivet Company introduced easily installed blind fasteners, which became the standard.
Their incredibly unique rivets offer significant joint integrity due to their "Safe-Lock" locking collar and meet PS-CMR-3000 requirements. They are also considered to be the most reliable and strongest structural fasteners available on the planet, and are available at Bay Supply.
This blog was originally published in February 2019 and updated in June 2020.