- Huyett Marketing Department
- 10/20/2022
Rivet nuts provide a clean and sturdy housing for bolts and screws to connect with when the mating material is too thin or weak to support the fastener on its own. These unique fasteners are also blind, which means they can be installed on one side of the mating material when the other side is not accessible. While their function is straightforward, they require specific tools for installation.
What is a Rivet Nut and How Do They Work?
To use these versatile fasteners correctly, it is important to understand what a rivet nut is, how they work, and how they’re installed.
What is a Rivet Nut?
A
rivet nut is a blind threaded insert that provides support in thin sheet materials when the clamping force of a bolt or screw would distort or break the mating material. The rivet nut features a hollow threaded body to house the mating fastener so it does not make direct contact with the mating material, giving the fastener a sturdy housing for the threads to grip.
The defining characteristic of a rivet nut is its collapsible body, which is what secures it in place and gives it its “blind” nature. Instead of securing a rivet nut with a fastener on both ends, the flange (the head) keeps it in place on the accessible side of the application while a
rivet nut tool secures the blind end. The tool’s function is to collapse the rivet nut on the blind side of the mating material in one of two ways:
Most rivet nuts will bulge just under the mating surface on the blind side, clamping the surface between the flange and the bulge. Swaging rivet nuts have a smaller threaded end that protrudes from the larger top half of the body. The installation tool forces the small end up into the large end, which expands the larger section enough to firmly secure the rivet nut in place on the blind side.
While many variations exist, a rivet nut’s basic anatomy is as follows:
How a Rivet Nut Works
A typical rivet nut application includes five main components: the rivet nut, a rivet nut tool, a mating material (the base material the rivet nut is installed in), an attaching component, and a bolt or screw. To install a rivet nut, drill a hole through the base material that is the same size as the rivet nut.
Next, attach the rivet nut to your rivet nut tool. You will need to thread the rivet nut onto the mandrel (a threaded protrusion uniquely sized for each type and size of rivet nut installation tool) on your installation tool and insert the rivet nut into the hole of the base material. The tool then pulls up on the rivet nut until it collapses. Each type of installation tool has a unique way of applying force to the rivet nut so it forms a bulge or swage on the blind side. Once this force is applied, remove the tool. The rivet nut is now ready to accept a bolt or screw and connect the attaching component.
Types of Rivet Nuts
Depending on the manufacturer and the characteristics they call out, similar types of rivet nuts may be defined or identified in a number of ways. While rivet nut manufacturers name their product lines after their own branding style, the characteristics they typically refer to are the shape, thickness, or variation of the head or body type. Other important characteristics are whether the rivet nut end is closed or opened or if the rivet nut bulges or swages during installation.
The following are some of the most common types of rivet nut characteristics to look for when
sourcing rivet nuts:
Sealed Head:
This feature provides resistance to water and other fluids by sealing the head. The seal’s material and placement will vary. Some rivet nuts offer a seal within the head, while others offer sealed protection on the outside of the rivet nut just beneath the flange.
Closed End or Open End:
This refers to whether the end of the rivet nut is closed or open. If it is closed, it will completely enclose the bolt or screw, which provides extra protection but will limit the length of fasteners that can be used in the application. If it is open, the fastener will be more exposed, but the length will not be limited.
Wedge Head:
These rivet nuts feature wedges on the underside of the flange to provide greater torque capacity and resistance to spin out.
Reduced or Heavy Duty Flange Profile:
A reduced (or thin) flange profile allows for nearly flush installation, while a heavy duty (or large) profile is thicker so it can handle heavier loads.
Thin or Thick Walls:
Rivet nut walls will vary in thickness, with thin walls being ideal for applications with reduced load requirements and thick walls providing greater load capacity for heavy duty applications.
Bulging or Swaging:
This refers to how the rivet nut collapses to secure it into place. Bulging rivet nuts will collapse just under the base material and firmly compress against it, while swaging rivet nuts expand and push outwards to form a wide body and are generally used with softer base materials.
Knurled Body:
A knurled rivet nut features lengthwise ridges running down the top half of a nut. When the rivet nut collapses, the knurls “bite” onto the mating surface to help increase security and reduce rotation.
Hex Body:
Hex rivet nuts feature either a half or full hex body. A half hex body has an internal hex shape just above the internal threads to provide extra holding power to the mating fastener. A full hex body will feature a complete external hex shape, which provides spinout resistance. These must be installed in hex-shaped holes.
Slotted Body:
These rivet nuts feature four slots along the shank that bulge out into a winged shape when the nut collapses. This bulge spans out beyond a normal bulge, providing extra holding power.
Stud-Style:
This style of rivet nut features a threaded stud protruding from the top of the rivet nut. The stud allows you to attach a
hex nut rather than a bolt or screw to the rivet nut. This style is available in round, knurled, and hexagonal bodies.
Floating Threads:
This is a unique design that features a floating threaded nut within the body of the rivet nut. Because the threaded nut can move within the body, it can make up for misalignment from the mating fastener when attaching other materials or components.
How to Use Rivet Nut Tools for Installation
Though there are several different types of
rivet nut installation tools, they all use the same basic installation method: the rivet nut is threaded onto the tool’s mandrel and inserted into a pre-drilled hole; the tool then applies a pulling force to the nut – whether manual or automatic – which causes the blind side to collapse to secure it in place.
The difference between each rivet nut tool is how they apply that pulling force and the application environment they are designed for. Some are handheld, while others are powered by battery or pneumatics. Some apply torque, while others use pressure. Some are designed for high production and industrial use, while others work well in slower paced environments and custom applications. When deciding on a rivet nut tool, consider the strength of the base material and the rivet nut, the ability to transport the tool if needed, the cost, the volume of use, and the wear and tear you may put on the tool.
Power Tools
Rivet nut power tools, or rivet nut guns, are tools that automatically install rivet nuts. These guns are available in three distinct styles:
pistol grip
(which looks like a power drill),
right angle
(for hard-to-reach areas), and
inline
(a straight tool for vertical installation).
Regardless of the shape of the gun, they all install rivet nuts in one of three ways:
- Spin-spin: After the rivet nut is threaded onto the gun’s mandrel and placed in the hole, the user engages the trigger. The mandrel pulls on the rivet nut by spinning it up towards the gun. When the nut is secure, the mandrel spins out from the rivet’s body.
- Spin-pull to pressure: This tool uses a customizable pressure regulator to determine the pressure at which the gun will stop pulling on the rivet nut. Powered by an air compressor, the gun pulls on the rivet nut after it’s inserted into the hole. When the pressure limit is reached, the mandrel is released with a spinning mechanism.
- Spin-pull to stroke: The installation method for this tool is the same as the spin-pull to pressure tool. However, this gun features a customizable stroke regulator, which determines the distance that the gun will pull the rivet nut, regardless of the amount of pressure on the nut.
These rivet guns use one of three sources of power:
- Battery: Battery-powered rivet guns use the spin-spin installation method. This gun is portable and works well in high-use applications where installation locations will vary.
- Pneumatic: Guns that utilize pneumatic power typically perform spin-spin installation. While the gun is not as portable as the battery-powered gun, it is ideal for high-production settings with predictable, repeatable actions.
- Hydro-pneumatic: Hydro-pneumatic rivet guns power both of the spin-pull installation methods. While the base of the tool is larger than a pneumatic gun, this gun is ideal for heavy duty applications.
Not every gun is compatible with every rivet nut, but most guns are compatible with a specific range of rivet nut sizes, which is why they feature a head piece that can be disassembled so you can replace the mandrel. This head piece usually consists of a hex driver, a threaded mandrel or cap screw, a nosepiece, and spacers (depending on the size of the nut). Some head pieces also feature a castle nut and anvil, while others may only need a mandrel and nosepiece. Investing in rivet power tool parts can help expand your gun’s usability.
Hand Tools
You can also install rivet nuts using hand tools. Hand tools are ideal for custom, low-volume applications for a range of materials. They are available in a variety of styles for different application needs.
Double Action Lever Tool:
This tool is ideal for larger rivet nuts and small custom production. It features two handles – much like shears – that squeeze together and a threaded mandrel at the vertical base. Once the rivet nut is threaded onto the mandrel and placed into the hole, the handles are squeezed inwards together to pull the rivet nut into a collapsed position. To release the rivet nut, the center handle twists to retract the mandrel.
Plunger Double Action Lever Tool:
This tool functions the same as the double action lever, except the central plunger pulls on the rivet nut after installation for a quicker, less labor-intensive release.
Expendable Tool:
The most economical option, this tool is ideal for everyday consumers in home repairs or projects. It features a small mandrel with a hex shaped head and a smaller hex shaped top piece. To install the rivet nut, connect it to the mandrel, hold the hex head in place with a wrench, and twist the smaller top piece with a second wrench. This will twist the nut into position. Rotate in the opposite direction to release.
Hi-Torquer Threaded Insert Tool:
The hi-torquer tool requires less exertion than the expendable tool and is well-suited for small-scale projects. After threading the rivet nut onto a mandrel and inserting it into the hole, the t-handle twists to exert a pulling force on the rivet nut and twists in the opposing direction to release its hold.
Threaded Insert Hand Tool:
This tool functions similarly to the double action lever tool, except the rivet nut is installed at a 90⁰ angle from the handles. This provides a good installation option when the space allows for downward handle compression.
It is important to remember that each installation tool will have its own specific guidelines for installing different types and sizes of rivet nuts. For safe and secure installation, carefully read and follow each tool’s instructions.
How to Remove Rivet Nuts Without Tools
Rivet nuts are non-reusable permanent fasteners. If removal is required because of poor installation or because the application will be disassembled, removal tools exist, but it may be helpful to have alternative removal methods.
If the initial rivet nut was poorly installed, you must be careful not to damage the mating material or the hole so you can easily replace the nut. The best way to remove the rivet nut without a tool in this scenario is to drill it out with a power drill and a drill bit that fits in the rivet nut body. Drill into the rivet nut slowly to reduce damage. The rivet nut should pop out of place when it is removed. This method may still cause some damage, so it is important to drill slowly and be prepared to repair the mating material or drill a larger hole for the replacement rivet nut if the hole is damaged.
If you are removing rivet nuts because you are disassembling an application, you may not need to worry about keeping the material intact. In this case, you can remove the rivet nut by grinding off the head and punching out the body with a screwdriver or similar tool. You can also use a chisel to remove the head, although this is more time consuming and laborious. These methods will almost certainly damage the material, so keep that in mind as you decide how to remove the rivet nut.
To learn more about rivet nuts and their tools, visit our
product FAQs page. You can also visit our
Sherex and
AVK supplier pages to learn more about the high-quality product lines we offer in low minimum quantities and competitive prices. For questions or quotes, contact our Sales Team at
(785) 392-3017 or
sales@huyett.com.
