Blind bolts are the fastener of choice for manufacturing, construction, consumer electronics, shipbuilding, automobile manufacturing, and a host of other industries and applications. Blind bolts are so popular because they are stronger than nuts and bolts, can be installed from one side of the material, stand up against heavy vibration, and don’t require special skills to install.
Installing welds or rivets requires special training and expertise. With blind bolts, you place the bolt in the pre-drilled hole, pull the trigger, and the job is done. And because of their design, you can tell by simple visual inspection if the blind bolt is properly seated. Blind bolts can be used in tight spaces and other configurations where other types of fasteners are impossible to install, and anyone can perform the installation.
Of course, you still need to choose the right blind bolts for the task, and that means choosing the right blind bolt installation tool, as well.
Choosing the Right Blind Bolt
Although the basic design of every blind bolt is the same, they do come in different sizes, lengths, designs, and materials. Depending on the task, you want to choose the right blind bolt for the job, which also dictates the kind of blind bolt tool you need.
Blind bolts consist of a collar, a sleeve, and a steel pin. You insert the bolt into a pre-drilled hole that matches the collar size. As you apply pressure to pull up the pin, the sleeve collapses on the blind side, forming a tight seal that cinches the bolt to connect two or more pieces of material. At the same time, the collar tightens on the visible side of the joint, and when installation is complete, the tool removes the excess section of the pin. Installation is basically a matter of point and pull.
When choosing the right blind bolt, there are various factors to consider. The bolt’s strength is a factor of the length of the fastener. The grip length is the distance from the underside of the collar to the first thread in the pin shaft. You use special grip gauges inserted into the hole to determine what size delivers optimal strength. Blind bolts also come in various sizes, typically ranging from 3/16-inches to 3/8-inches or larger—the bigger the bolt, the greater the shear strength.
Commercial Blind Bolts like the Huck® BOM and Avdel® Avbolt are primarily available in steel, and are designed for high clamp loads in a variety of high-strength application requirements. Aerospace Blind Bolts are also available in more exotic alloys and materials for specific aerospace, military ship building, and specialized defense systems.
You have to match the tools to the blind bolts. There are different tools designed to accommodate the size and type of bolt, the application, and the installation environment.
Choosing the Right Tool
There are two basic types of blind bolt installation tools. Pneudraulic installation tools are connected to air power via a single airline from a standard air compressor. Hydraulic tools are connected to multi-line hydraulic hoses and are powered by specific hydraulic fluid pump units. Hydraulic tools are typically triggered using a low voltage electric control that is included on the power pump. Pneudraulic tools require a nose assembly that can be fitted to the bolt size and require minimal operator training.
Hydraulic tools use liquid under pressure for power and require a power pump, as well as a nose assembly for different bolts. The hose assembly requires fluid pressure adjustments for proper operation, and these tools have a significantly higher pulling capacity compared to pneudraulic tools. They also require more advanced operator training.
Bay Supply carries an array of blind bolt tools from Avdel and Huck, the leading blind bolt brands:
- Avdel 7300 – The Avdel 7300 is a pneudraulic tool with air pressure between 75-100 psi and a 0.79-inch stroke, and it delivers a pull force from 6,823-8,138 pounds. It has a 3-second cycle time and weighs 10 pounds (without the nose hardware), which is light enough for handheld use.
- Huck 254 – The Huck 254 is a pneudraulic riveter that uses a combination of air and hydraulic fluid with a 0.565-inch stroke and a pull capacity of 8,620 pounds. The Huck 254 has a cycle time of 30 bolts per minute and weighs in at 8.67 pounds.
- Huck 256 - The Huck 256 is a pneudraulic riveter with a 0.875-inch stroke, optimal for one-cycle installation. It is meant to be used in high-speed production applications, with the ability to install up to 20 bolts per minute.
- Huck 2581 – The Huck 2581 is a hydraulic riveter with a 0.937-inch stroke and a pull capacity of 7,400-10,700 pounds, depending on the psi. It weighs 5.5 pounds.
- Huck 940 Powerig – The Huck 940 Powerig is also hydraulic-powered, delivering 5,400-5,700 psi that transforms into a pull pressure from 2,200-2,400 psi. This is a self-contained, portable unit weighing 66 pounds and is designed for moderate production and repair applications.
- Avdel Enerpac Power Unit Pro115E and Pro220E – The Avdel Enerpac Pro units are self-contained hydraulic pump units designed for power use at 115 volts (Pro115E) or 220 volts (Pro220E). They feature high-efficiency motors designed to deliver a maximum operating pressure of 10,000 psi and weigh in at 70-115 pounds.
These are just some of the tools available for blind bolt installation. As you can see, each tool has different pull pressures and is designed for different types of blind bolts and different applications. If you’re trying to decide which tool will work best to install your blind bolts, consider working with an industry-tested distributor, who can recommend the best bolt and tool for your needs.