What is a BLIND RIVET NUT | BLIND RIVNUT®?

Blind Rivet Nuts, or Rivnuts®, are fasteners that provide a threaded hole in materials that are too thin or where access to the backside of the application is limited for a traditional nut-and-bolt system. These fasteners are basically a 2-in-1 product because of their nut and rivet combined design. Once the Blind Rivet Nut is installed the user can use the threads to easily install or remove an additional screw. This setup makes installation easier, faster, and creates a stronger threaded connection from the Blind Rivet Nut to the parent material.

History

Before the invention of the Blind Rivet Nut, traditional fastening methods such as bolts, screws, and standard hex nuts were commonly used. These methods often required access to both sides of the assembly for installation, which could be cumbersome or impossible in many applications, especially in thin materials or confined spaces. Additionally, in cases where materials were thin or prone to deformation, traditional fasteners could weaken the entire structure where the installation was located, risking failure. Because traditional fastening solutions relied heavily on manual installation methods, the overall performance was inconsistent and could lead to field failure (such as tension loss between the bolt and hex nut in a vibratory environment).

The Blind Rivet Nut, also known as a Blind Rivnut®, was developed in the mid-20th century. Its design involves a tubular nut that can be installed from one side of the workpiece, expanding to create a strong anchor point. Initially emerging as a solution for creating a strong threaded application in the aerospace and automotive industries, the Rivnut® allowed for significant enhancements in design flexibility.

Overall, the limitations of pre-rivet nut fastening solutions created many challenges for innovation and efficiency in design and manufacturing across various industries. The introduction of the Blind Rivet Nut eliminated many of these issues, helping to pave the way for more efficiency in production and stronger more long-lasting applications.

Structure and Design

A Blind Rivet Nut consists of a cylindrical body with a head flange at one end, and internal threads through the middle of the body. Their ability to be installed blindly, meaning without needing access to the backside of the parent material, makes them ideal for applications that have limited access to all areas of the material. The body is designed to upset or bulge on the backside when a specified amount of torque is applied, creating a strong bond with the parent material which is usually a thin piece of metal or plastic. By distributing loads evenly due to their strong anchor point, Blind Rivet Nuts essentially eliminate the risk of damage to materials, further enhancing their ease of use. Installation is user-friendly, requiring minimal tools, and no lengthy instruction book.

The internal threads of Blind Rivet Nut allow for secondary (child) applications to be affixed and easily removed to the parent application, using a mating male bolt. A Blind Rivet Nut can be installed simply by using a basic installation tool. The tool’s mandrel is inserted into the internal female threads of the Blind Rivet Nut. As the Blind Rivet Nut is installed, it squeezes the front and back of the parent material to create a tight secure connection. Using the internal female threads allows screws or bolts to be easily inserted and removed, making the repair process easier and quicker. This design feature contributes greatly to lowering production time because of the speed at which the production workers can install the components which also reduces labor costs. They come in various sizes, materials, and finishes, making them versatile for different applications.

Types of Blind Rivet Nuts

Flat Head “The Original” Rivet Nuts: These are the original type of Blind Rivet Nuts used extensively in legacy applications and new applications. The flat head flange features a thick wall that provides a larger bearing surface for load distribution and durability. It was designed for use in round drilled or punched holes. The original Bollhoff Rivnut® is designed for use with class 5 mating hardware (inch) or class 8.8 mating hardware (metric). Rivet nut material choices include aluminum, steel with zinc plating & stainless steel. Flat Head Rivet Nuts are available with open or closed ends. Countersunk Head Round Body: Similar features as it’s “Flat Head” relative noted above, but instead provides  a 100-degree countersunk head for a completely flush installation.

Knurled Flange Rivet Nuts (aka “low profile” series): These blind fasteners have a knurled surface that enhances grip, preventing the nut from spinning or slipping during installation. Knurled Rivet Nuts were developed to provide users with a reduced cost alternative to the traditional heavy-duty rivet nut when that level of superior strength isn’t required. The Knurled Rivet Nut still offers a solid performance that typically will suit most applications. There are many options to choose from with these fasteners in regard to head thickness, body style, including round or half-hex shape, and material. Some people refer to this as the “low profile” series, which is not necessarily correct, but has been used as a term for so long in the industry that it has come to gain permanent association with these knurled rivet nuts. Knurled rivet nuts typically have a thinner wall, which saves some money on material cost, while still offering robust field performance. Sometimes, they have a “low profile” head, but not all the time.  Some are just “regular heads”. Thus, it’s not appropriate to call all knurled rivet nuts as “low profile”.

Rivet Nut with Pre-Installed Male Threaded Stud (RIVSTUD®): A female rivet nut with the male threaded bolt pre-installed into the rivet nut. The secondary attachment can be placed over the male bolt and secured with a female hex nut.

Swaging Rivet Nut: These Blind Rivet Nuts are permanently embedded within materials such as metal, plastic, or composites to provide a reliable and durable threaded anchor point.  This is a good choice when the parent material exceeds 1/2 (0.500”) inches thick, as it can install itself into parent materials of “unlimited” thickness since it does not require “grabbing” the backside of the application.

Hex Rivet Nut: These Blind Rivet Nuts are designed with a hexagonal body style, which means they have a six-sided body which is different from their traditional round body rivet nut counterpart. Hex Rivet Nuts provide the ultimate spin-out resistance when used in a hex hole.

Plus Body Rivet Nut: This option, originally known as the Bollhoff Plusnut®.that provides the most pull out strength in thin sheet metals and soft plastics, would be the Plus Body Rivet Nut. It features a slotted body that during installation split into four legs gripping the parent material tightly making a “plus” shape. This helps provide a wide load-bearing surface on the backside of the parent material. This splitting is why they are sometimes referred to as split rivet nuts.

Blind Rivet Nuts with Seal Ring (Waterproof Rivet Nut with O-Ring): These fasteners are used in applications requiring moisture or dust resistance, as they are designed to prevent leakage. The O-ring sealing benefits offer a waterproof seal which protect your assemblies from external environmental factors (water, rain, salt, air, gases, etc…), which ensures waterproofing against all fluids.

The parent to a “blind rivet nut” is a “blind rivet”.  A blind rivet is used when needing to permanently join together a parent material to a secondary (child) material is required.  A Few Types of Blind Rivets include:

Standard Blind Rivets: A standard blind rivet is a fastener that is inserted into pre-drilled holes and is installed from one side to securely join two or more materials together without needing access to the back side.

Structural Blind Rivets: A structural blind rivet is a high-strength fastening solution designed to join thick materials and withstand heavy loads, typically featuring a larger mandrel and a wider grip range for increased durability.

Multi-Grip Blind Rivets: A multi-grip blind rivet is a versatile fastener designed to accommodate a wide range of material thicknesses and grip range requirements while providing security and reliability with a single rivet.

Huck® Bolt | Lockbolts: A Huck® Bolt, or Lockbolt, is a high-strength component that consists of a pin and a collar, which are swaged together to create a secure, permanent application capable of withstanding heavy loads and vibrations.  Note:  While this is a common fastening solution and people think this is a blind installation, it’s not true.  Lockbolts require access to the backside of the application, in order to “swage” or “install” the collar onto the bolt.  The collar “locks” onto the backside of the bolt.

Applications

Blind Rivets, Rivet Nuts or Blind Rivnuts® are utilized across multiple industries due to their versatility. Pictured below are just a few common applications where these blind fasteners are used: Automobiles (such as holding the dashboard together), Agriculture (such as attaching a wheel fender to the tractor body), Aerospace (deicers) and Electronics (affixing a circuit board to the electrical enclosure).

At Rivet Nut USA™, a division of Cardinal Components, Inc., we offer high-quality Blind Rivet Nut and Blind Rivnut® fastening solutions suitable for various industrial and domestic applications. Choosing the right Blind Rivet Nut for your application can sometimes be complex because of our wide range of products and the vast number of options. That’s why Rivet Nut USA™ provides expert support to assist you in selecting the best fastening solution. Our knowledgeable team is available to answer questions, provide guidance on product solutions, and help you navigate through our extensive inventory to find the right Blind Rivet Nut for your project. For more information or to receive more help to differentiate What is a BLIND RIVET NUT | BLIND RIVNUT®, contact Rivet Nut USA™ today!