Differences Between Threaded Rivet Nut Insert Styles
When choosing the right style of rivet nut insert for the job, it’s important to understand the characteristics of each style, including strengths and weaknesses. Here is a more detailed look at the various styles of threaded rivet nut inserts.
Round and hexagonal body inserts
Both round body and hexagonal body inserts are available in standard or metric threading. They also come in open- and closed-end configurations with either flat or countersunk heads. The inserts are available in a range of materials, including steel, stainless steel, alloy-hardened steel, and aluminum. The alloy-hardened steel inserts are available with a thread locking feature. All of these units are also available with a non-keyed or keyed head.
The round body inserts also come in both ribbed and smooth body designs, with both open and closed shanks:
- Open-end smooth shank round inserts – Open-end smooth shank inserts are blind threaded rivet nut inserts specifically designed to provide load-bearing joins in thin sheet materials. There is a large flange version that provides a greater load-bearing surface for the thin sheet nutsert.
- Open-end ribbed shank round inserts – These blind rivet nuts are designed for high-torque applications with ribs along the shaft for a better grip. They also have countersunk features so they can be installed flush with the material surface.
- Closed-end smooth shank round inserts – These threaded inserts are designed for heavy-duty applications with a thicker head profile and increased wall thickness in the collapse area. This particular threaded insert is ideal for applications requiring heavy push-out loads, such as leg-leveling screws on heavy equipment. They also offer superior thread strength thanks to an internal rolled thread manufacturing process. These inserts are corrosion-resistant because the threaded area is enclosed, which eliminates leaks getting past the threads from either side.
- Closed-end ribbed shank round inserts – Designed with a rib feature for high-torque applications, these blind rivet nuts have a countersink feature that allows them to be installed flush with the surface of the workpiece.
Thin-wall rivet nut inserts
There are a few types of thin-wall rivet nut inserts:
- Thin-wall threaded rivet nut insert – Like thick-wall rivet nut inserts, the thin-wall inserts come in both round and hex body designs, and they typically have a wide-bearing head for a stronger bond. The round body inserts also have a low-profile head available.
- Nutserts – Nutserts are a type of round thin-wall threaded insert with a low-profile flange for near-flush installations. They are designed so the inner body pulls into the outer body for a tight seal. Nutserts come in configurations for various specialty applications. For example, a standard splined nutsert is designed for applications in which you want a minimal protrusion on the blind side. A “W” Series nutsert is a knurled threaded insert designed for applications in thick fiberglass, such as boat building, and it can be installed prior or after finish. Superserts are structural locking threaded inserts.
- Stud-style locking rivet nut inserts – Stud-style locking inserts include the bolt; once they are installed in a predrilled or punched hole, they can accept a nut for fastening. Stud inserts are available in various styles, thread sizes, head types, body materials, and stud lengths.
Bay Supply stocks four popular types of thin-wall inserts: L-style round body inserts that can be used in drilled or punched holes; K-style round body inserts, which are smaller with a smaller head for near-flush mating part assemblies; O-style round body inserts with reduced profile heads; and H-style hex body inserts, which are designed for maximum torque strength.
Slotted body with wide tail formation
Slotted body threaded rivet nut inserts are available with round bodies that feature slots that collapse as the bolt is tightened. They are available in both a straight shank body design, in which the outer body pulls into the body of the nut for a strong connection, and pre-bulbed body design, in which the body collapses and grips the blind side when tightened. There are a couple of different types of slotted body inserts:
- The straight slotted body threaded insert features a wide grip range with an extra-large grip on the blind side. It was specifically designed for use with soft materials, such as composites and plastics, and is easy to install. Using simple hand tools, it can be installed with only blind-side access in less than three seconds. The extra-large blind side area resists pull-out and offers higher torque-to-turn resistance in brittle materials. It is typically used in auto trim moldings, domestic appliances, handles, and plastic fabrications.
- The pre-bulbed shank body insert also works well with plastics and thin-gauge steel where you need additional resistance to prevent pull-out. When it’s installed, four segments fold onto the blind side of the workpiece, creating a strong join. It features a very wide grip range and has four high-load-bearing legs when tightened. It can be used in single, variable, or multiple thickness materials.
Slotted body threaded inserts are available in both standard and metric thread sizes, and they come in steel and aluminum in various body styles.
Other threaded inserts used for specific applications include Euro-style, wellnut, Jack nut, and riv-float inserts:
Euro-style or hard metric threaded inserts
If you need metric threaded rivet nut inserts, the Euro-style or hard metric inserts are right for you.
Euro-style inserts are available in steel, stainless steel, and aluminum. They come in the same body styles as the thin-wall inserts, but with metric threads. They also come with flat, low-profile countersunk heads.
You can choose from round body, semi-hex body, full-hex body, heavy-hex body, and square body Euro-style insert types.
Unlike a threaded rivet nut insert, which accepts a bolt, a threaded stud-style insert is designed to accept a nut. The round body shape is similar to that of a thin-wall insert. Stud-style inserts have a knurled or semi-hex body to prevent the insert from turning. Upon installation, you have a secure stud that can accept a nut to complete the joint.
Stud-style inserts are available in standard and metric threads and come in various lengths. They also come in different materials and can be coated to prevent corrosion.
Wellnut threaded inserts are designed to create a seal at the same time they create a join. They are designed as neoprene bushings with a machine nut molded into one end. Tightening the machine screw causes the insert to expand, creating a watertight, vibration-resistant join. Wellnut inserts are especially useful in automotive and industrial applications, such as for motor and shock mountings, as well as in boat building and waterproof applications.
The most common wellnut inserts are made of neoprene and EPDM rubber with a brass internal nut. They are available in standard and metric threading.
Jack nut inserts
Jack nut or Molly threaded inserts are an economical type of blind fastener typically used in assembly line applications. They are made of thin, soft, or brittle materials. When tightened, the legs collapse on the blind side of the parent material, leaving a firm, reusable threaded insert. They come in steel, brass, and steel with PVC or Raintite coating for added protection against corrosion.
Jack nut inserts are normally used in blind holes and won’t deform soft plastics or thin sheets of metal. They also are not sensitive to hole size and will fasten securely, even if there are burrs or an uneven substrate. They can be set using manual tools or using pneumatic tools for fast setting.
Riv-float threaded inserts are used to connect off-center or misaligned holes and can compensate for tolerance stack-up in manufacturing. The floating nut aligns with the bolt to accommodate the angle of the screw for a strong join. These inserts were designed to replace cage nuts, clinch nuts, floating nut plates, and weld plates.
Riv-float inserts are made of steel and available in standard and short body lengths with both standard and metric threading.