Fasteners come in all shapes and sizes, and when you choose the right fastener for the task, you want something that is easy to install and that provides a reliable joint. That’s why rivet nuts are frequently the fastener of choice for use in the field and on the assembly line.
A rivet nut, sometimes referred to as a rivnut or nutsert, is a member of the blind fastener family. With most fasteners, such as nuts and bolts, you need access to both sides of the joint. Rivet nuts only require access to one side. The tubular rivet nut is inserted into a pre-drilled hole and a mandrel is screwed in to form a tight-fitting bulge on the blind side of the workpiece.
All blind-side fasteners are designed to create a joint in basically the same fashion. The fastener is inserted into a pre-drilled hole, and when the mandrel is applied, it forms a bulge on the blind side to form a seal. What makes rivet nuts different is that they are permanent, threaded nuts that are fixed in place to receive a threaded insert.
Rivet nuts are frequently used to replace weld nuts and for applications where you want a lasting connection. You also can install them without having to use hot welding, making them ideal for softer materials such as plastic and fiberglass.
Basic Types of Rivet Nuts
The rivet nut itself is a threaded sleeve that is inserted into a pre-drilled hole. The nut is inserted from one side of the workpiece and a threaded mandrel is screwed into place. As the mandrel is tightened, a bulge forms on the blind side of the joint creating a strong connection.
There are a variety of different types of rivet nuts for different applications, but there are two basic rivet nut designs that are installed using different types of tools with different actions.
The first type requires a spin-spin tool, which takes a mandrel threaded on the nosepiece and drives it home using a clockwise screw action to completely collapse the nut and form a bulge on the blind side. The tool then screws the head in the opposite direction so it can be removed.
The second type uses a spin-pull tool that screws the mandrel in place, then uses a pulling motion to form the bulge on the blind side before reversing the spin action to release the tool.
For special applications, there also are pull-to-pressure tools that will apply a preset amount of pressure so as not to crush softer materials, such as wood or plastics.
The Advantages of Rivet Nuts
Rivet nuts come in various shapes and configurations so they can be used in a wide variety of applications. Some are round and some are hexagonally shaped, which keeps them from turning in the hole during installation and makes them ideal for use with woods, plastics, and soft materials. Some are made of rubber to create a watertight seal. Whatever type of rivet nut you choose, they all have similar advantages:
- They are blind fasteners, so they are reliable, strong, and vibration-resistant. The beauty of blind fasteners is that they can be installed from one side, which is why they are so popular for applications such as automobile and aerospace manufacturing. The design also forms a lasting joint that, unlike those formed by nuts and bolts, cannot work loose even under constant vibration. Rivet nuts are installed to last.
- They create a threaded, removable joint in any material. Where blind rivets form a permanent bond, rivet nuts form a solid foundation to screw in bolts or other threaded fasteners. They also can be installed in virtually any material. In hard metals, for example, they provide a permanent threaded nut that will not pull out. They are also ideal for softer materials such as wood, fiberglass, and plastics, which is why they are used to create furniture, boats, and even consumer electronics—any application that requires easy disassembly and reassembly.
- They are ideal for mass production and can help lower installation costs. Rivet nuts work well on the assembly line, so they are perfect for factory or assembly line applications, where they can shorten production time and reduce costs.
Because there are so many rivet nut insert types and applications, you want to choose the right fastener for the job. That’s why our team of fastener experts is available to answer questions and offer advice. Feel free to contact us to review your fastener needs.
There is a lot to know about rivet nuts and threaded nut inserts. To learn more, be sure to review our e-book, The Essential Guide to Threaded Rivet Nut Inserts.