Whenever you are working with fasteners, you want to be sure you have a strong, durable rivet or bolt that is suited to the job. Blind threaded inserts are among the most versatile types of fasteners, and there are thousands of types from which to choose. Choosing the right threaded insert depends on the nature of the materials you are working with and the application.
What’s a Threaded Insert?
A threaded insert is a sleeve with a threaded interior that can accept a bolt or threaded fastener. The insert can have different dimensions, be made of different materials, and come in different configurations or tooling; its design will hold fast in thin or soft materials, making the threaded fastener secure.
If you have devices that need to be disassembled and reassembled or that use particularly soft materials, threaded inserts offer a number of advantages, especially if the connection is load-bearing. Flexible plastics, for example, have difficulty holding a threaded bolt because the threads in the tap hole aren’t durable enough. Rather than relying on threads drilled into the soft workpiece itself, a threaded insert gives you more strength and more versatility and tends to be more resilient over time.
Designed with Automation in Mind
Blind threaded inserts can be installed from one side, enabling faster installation, especially in a production line. They offer a stronger alternative to weld nuts and tapped holes, and they provide a stronger bond than self-tapping screws. In fact, threaded inserts are usually the strongest and least time-consuming fasteners used in any manufacturing setting, especially because they were designed for automation.
Threaded inserts have ribbed walls that offer greater strength under load. They can be used at virtually any stage of production, including after a workpiece is painted or coated, because they don’t require reworking once they are installed. That’s why blind threaded inserts have become so popular in applications such as aerospace, defense, transportation, clean energy, medical applications, and electronics.
There are a variety of different types of threaded inserts, each with a different design for a specific application.
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Rivet nut inserts, sometimes referred to as blind rivet nuts, can be installed from one side of a joint and have a counter-threaded interior designed to accept a bolt. Some rivet nuts will bulb on the blind side to create a solid connection. Others are designed to pull the rivet nut into the sleeve as they are tightened.
Rivet nuts were first used to connect thick-walled materials in the 1930s, when RIVNUT® fasteners came into extensive use in aerospace manufacturing. When securing metal, thick-wall threaded inserts are often used. These are the most common types of inserts and come with both ribbed and knurled bodies, as well as smooth bodies in round, hexagonal, semi-hexagonal, and other shapes. They are made of different materials and come in different shapes, including large and small flanged heads, open and closed-end, and other designs.
Thin-walled inserts came later in round, hexagonal, and square designs. These inserts offer added versatility, such as using sealant under the head or special plating for greater durability in harsh conditions.
They also come in a knurled body design for a better grip on the material. For thicker fiberglass materials, such as those used in boatbuilding, knurled inserts are often used to minimize corrosion.
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Eurostyle inserts are round-body threaded inserts with semi-hexagonal, fully hexagonal, heavy hexagonal, or square body designs. They are available from a variety of manufacturers, including Avdel, Atlas, and Sherex Fastening Solutions.
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Slotted body threaded inserts are designed with gashes in the body that expand when the bolt is tightened for a firm connection. Slotted-body threaded inserts are commonly used for thin-gauged metals, such as aluminum. This insert has cuts along the body that come pre-bulbed to collapse on the blind side to secure the insert. There are straight-body and pre-bulbed body types from manufacturers such as Avdel, Atlas, Sherex, AVK, Goebel, and Marson.
Self-Tapping Inserts
Yardley self-tapping inserts are ideally suited for high volume assembly operations because of their easy, quick installation. Inserting a self-tapping insert is as simple as driving a self-tapping screw or tapping a thread. A drilled hole of correct size must be provided, driver tool is applied to insert, driver and insert are positioned over the hole, insert is driven (turned) home and the driver is backed off, leaving the insert installed. The insert cuts its own threads as it is driven into the base material. The methods listed below can be used to install Yardley TRI-SERT and FIBERSERT inserts.
Because it is driven by its internal threads, a different driver is required for each insert size. Thread cutting can be accomplished on either end because there is a lead in both ends of the insert. Alignment is important and the insert should be used with a hand tapper or a tapping head attachment on a drill press without a lead screw. For applications in recessed areas or close to walls or ribs, a Yardley Extension Driver may be used to facilitate installation. Inserts should be installed flush or below material surface. Thus, when one assembles a bracket and screw to the insert, the load is not transmitted directly through the insert but to the surface of the boss or the material in which the insert is installed. This is especially important where vibration is encountered.
The ultrasonic process converts electronic energy into high frequency mechanical vibration. The ultrasonic equipment operates from a normal 60-cycle line current and converts this to an output of 20,000 cycles per second. The output of the power supply received by the ultrasonic press that is similar to an arbor press in that there is a longitudinally moving arbor or tool. In this moving arbor, the oscillating electrical input of 20,000 cycles per second is converted to a mechanical vibration of 20,000 cps.