In a previous post, we discussed many of the different types of standard fastening nuts. In this edition, we’ll talk about locknuts. The major difference between standard nuts and locknuts is standard nuts consist simply of a threaded hole, while locknuts are designed to prevent loosening when exposed to vibration. As with standard nuts, there are many different variations of locknuts from which to choose. We’ll take a look at some of the more popular locknuts here.
The speed and ease of installation of blind fasteners make them an excellent choice for manufacturers of all types of products. This is especially true when access to an application's backside is limited at best or completely inaccessible.
Once determined that a blind fastener is right for the application, the user then must decide which type of blind fastener is most appropriate. While many factors could play into this decision, strength requirements and vibration resistance are two criteria that sit at the forefront.
For lighter duty applications that are not load-bearing (under 100 lbs. of shear and tensile strength), a standard blind rivet is often adequate. For more information on standard blind rivets, check out our four-part series on blind rivets.
This is Part 4 of a 4-part series on Blind Rivets
In the first three parts of our series on blind rivets, we discussed the history of blind rivets; the most important factors to maximize joint integrity (grip range, hole size, material, and installation tooling); rivet selection (material, diameter, grip range, head style), and the most common types of blind rivets (drive-pin and break-stem; open-end, closed-end, self-plugging). To review any of those posts, please click on any of these links.
In this final installation, we’ll break down some other variations of blind rivets. There are many different styles of blind rivets for specific applications, including different types of structural blind rivets.
Structural blind rivets are required for applications requiring higher load and vibration tolerances. They have higher shear and pull-out strength than standard blind rivets. Many offer a wide grip range, while most have exceptional clamping force. While they’re not quite a replacement for a blind bolt, such as the Huck BOM, or heavy hex bolt, they are a great option when a standard blind rivet just won’t suffice.
This is Part 2 of a 4-part series on Blind Rivets
In part one of our series on blind rivets, we briefly looked at the history of the blind (a.k.a. pop) rivet and discussed the two most important considerations to maximize joint integrity when using them: Grip Range and Hole Size. If you have not yet read that post, click HERE.
We'll now break down the third and fourth most important aspects to consider to maximize joint integrity using blind rivets: Material and Installation Tooling.
- Material - A good rule of thumb when selecting a blind rivet is to use the same material rivet as the substrate into which it's being installed. If you're riveting sheets of steel together, use a steel rivet. The same goes for aluminum and stainless steel. This is important because using dissimilar metals may result in galvanic corrosion, depending on the application's environment.
Installation Tooling - What role exactly does installation tooling play in how a blind rivet works? It's simple. An installation tool has one job … to pull the stem of the blind rivet up through the rivet body until the pull force of the tool overcomes the tensile strength of the rivet stem, resulting in the stem breaking off at its predetermined breakpoint.
There's nothing more to it than that. All strength parameters and application criteria of a properly installed blind rivet reside within the rivet itself. If the installation tool breaks off the blind rivet stem, it's done its job. So, this means that the primary consideration for blind rivet installation tooling is accessibility. Can the tool fit into the area around where the rivet needs to go? Fortunately, there are many different configurations and types of tooling available. So, in most cases, you'll find an installation tool that quite literally "fits" your needs.
In an earlier post on structural fasteners, we began discussion on lockbolts. A lockbolt is a 2-piece, permanent, mechanically locked structural fastener. Their primary benefit is that they offer long-lasting vibration resistance and won't loosen even under the most extreme vibration. This is because an installed, fully swaged (cold-formed collar on the grooved pin) lockbolt has no gaps between the grooves of the pin and the swaged collar, as found in threaded fasteners such as nuts and bolts. It's essentially a best-of-both-worlds hybrid of a bolt and a rivet.
Lock washers work on the nut side of the fastener, supplying added tension to an assembly to help prevent nuts and bolts from turning, slipping, and coming loose due to vibration and torque. Thus, their use is common in the transportation industry and on commercial products such as washing machines where vibration is a significant factor.
E-Clips are a radially assembled tapered section retaining ring. With three points of contact they provide a larger surface for retaining, and yield a higher thrust load capacity than other types of external rings.
As discussed in a previous post, retaining rings are designed to restrict the movement of mating components and keep them securely in place during operation. By creating a shoulder to retain the assembly, retaining rings are a cost-effective solution, reducing the need for threaded fasteners or machining shoulders on to components. They can be used to replace cotter pins or other traditional fasteners in a number of applications.
Composed of thin metal, retaining rings are generally either stamped, machined, or made from coiled wire.
They function by being fitted into a machined groove, either on the inside of a bore, or the outside of a shaft. Once in place they reduce vibration, maintain placement of two parts of an assembly, and withstand axial loading.
A grooved pin is a solid pin, similar to a dowel, except with swaged grooves (or flutes) that run vertically. Ordinarily, there are three grooves that can vary in length. They can run the entire way down the pin to as little as just one-third the length.
- Locking collars
- Linkage or Hinge Pin
- Valve T-handle
- Spring anchor
- Roller and Stop pins
Typically, sizes range from 1/16” to ½” in diameter, with lengths up to 3-3/4”. Grooved pins generally are used in friction fit holes, creating a connection that is almost as strong as a dowel with the added benefit of excellent vibration resistance.
The primary functional difference between a grooved pin and a dowel is that, while displaced material of the swaged grooves increases the pin’s diameter, the grooves close when pressed into a hole. This makes grooved pins appreciably more pliable than dowels, resulting in pins that can be used in holes that may not be formed to an exact size or circular shape. Tolerances for a dowel are considerably tighter. Grooved pins can also be removed and reused more easily because of their enhanced pliability.
In a previous post, we discussed in broad terms the basics of self-clinching fasteners. We noted that self-clinching fasteners are typically used for metal assemblies that may be too thin for tapping or in applications where it’s not feasible to employ stamped or extruded threads. They’re found in everything from household appliances and electronics to medical, telecom, and automotive equipment.
The three primary forms of self-clinching fasteners are Nuts, Studs, and Standoffs. Standoffs are used most often in Printed Circuit Boards and electrical assemblies to protect the circuitry. Studs present a threaded fastener into the product allowing for the mounting of essential components. We’ll dive deeper into those two specific self-clinching fasteners in future posts.
This blog is going to take a little closer look at self-clinching nuts.
Self-clinching nuts provide strong, load-bearing threads to accept bolts and screws in thin sheet metal applications. They’re typically pressed into the metal using a manual or hydraulic press and swage the surrounding metal, which makes them a strong and permanently affixed component.