Not all fasteners are created equal. A different type of fastener is available for every type of application you can think of, and choosing the right fastener for the job ensures a lasting and trouble-free joint. The question is, which of the myriad fastener types is appropriate for each task?
Here are four of the most common applications that require fasteners and the best types of fasteners for each one.
There are a variety of applications in which the joint is going to be subjected to continuous vibration or regular shaking. In these circumstances, a regular nut and bolt will loosen over time. You need a fastener type that, once installed, will provide a lasting joint, such as a lockbolt or a coil thread insert.
Like nuts and bolts, a lockbolt consists of two pieces: a pin and a locking collar. The difference is that the collar forms a permanent joint with the pin. Like a bolt, the lockbolt is inserted in a pre-drilled hole from one side of the material and the collar is placed on the pin from the other side. Using the appropriate tool, the lockbolt collar is then swaged against the pin; the pin is pulled to bring the material pieces together, and the collar is then pressed into the threads in the pin to form a permanent bond. The more metal-to-metal contact between the collar and the pin, the stronger the joint. No lock washer or additional pieces are needed.
Where the lockbolt serves as a substitute for a bolt that can withstand heavy vibration, you also can use a coil thread insert for a vibration-proof joint. As its name implies, the coil thread insert is a coil of wire that is inserted into a pre-drilled hole. When a bolt or fastener is screwed in place, the threads of the fastener are filled by the coil, which in turn exerts pressure on the walls of the hole. The extensive metal-to-metal contact and pressure create a lasting joint that won’t fail under continued vibration. Once installed, the bolt can be removed and reinstalled without harming the joint.
There are times when you only have access to one side of a joint. This was a common problem until early in the 20th century and used to require two people to install a fastener, one on either side of the workpiece. That changed with the invention of the blind rivet.
The term blind rivet specifically refers to a rivet that is installed from one side—you can’t see the other side of the joint, hence it is blind. Blind rivets have become popular in aircraft manufacturing, boat building, railcar manufacturing, and other applications in which you don’t have ready access to both sides of a joint.
The blind rivet consists of two pieces: the tubular rivet pin and the mandrel. To install a blind rivet, you place the mandrel into an installation tool and then position the rivet in a pre-drilled hole, placing the mandrel head against the material surface. When the installation tool is activated, it pulls the mandrel head into the rivet body, which collapses the blind side of the rivet to form a secondary head. Once the rivet is set, the mandrel breaks off to complete the installation.
When joining together thin materials, there is the risk that smaller-headed fasteners might pull through. You need a fastener that can spread the load across a wider surface area. Slotted body inserts are useful for such applications.
As the name implies, a slotted body insert is a cylinder with slots in the sides that is designed to collapse when tightened. For thin materials, the slotted body insert is placed through a pre-drilled hole so the head of the insert is snug against the workpiece. When tightened, the insert collapses on the blind side, creating a wide formation that can carry more load without pull-through.
Slotted body inserts are ideal for soft materials and composite materials, which usually require a straight shank insert, as well as thin-gauge metals and plastics in which a pre-bulbed insert is often used.
Factory Automation and Assembly Work
For assembly line applications or where you have a number of similar joints to make one after another, speed and accuracy are paramount. Speed fasteners and Huck bolts are usually the preferred fasteners.
Speed fasteners are blind fasteners designed to be installed quickly and efficiently. With most blind fasteners, each rivet is manually placed in the nosepiece of the installation tool prior to installation. But with speed fasteners, multiple rivets are loaded at the same time so they can be installed one after another. The objective is to reduce the cycle time to 1-2 seconds to cut assembly time. Speed fastening tools also tend to have longer nose shafts to accommodate preloaded rivet magazines.
Huck bolts are a form of lockbolt designed for fast, error-free installation. To install, a Huck bolt is placed through a pre-drilled hole and a collar is fitted on the opposite side. Using a special Huck bolt tool, the collar can be swaged over the Huck bolt pin 25-50 percent faster than other types of fasteners. Huck bolts have the added advantage of creating a permanent, vibration-resistant joint that will last.
These are just a few of the common applications in which specialty fasteners are used. There are many others. Rather than trying to guess which is the right fastener for the job, why not consult an expert who understands fasteners? Bay Supply carries thousands of different types of fasteners and hosts an extensive resource library with engineering specifications, data sheets, tool manuals, videos, and more. Contact one of our fastener experts and tell us what you need, or request a quote. We will be happy to assist you.