~ Article courtesy of Advance Components
Nut retainers are self-retaining spring steel fasteners that have a bolt-receiving nut floating inside a cage, which offsets typical hole misalignment. It does not turn when the bolt is tightened. Essentially, nut retainers combine the advantages of spring steel fasteners with the strength of a multi-threaded nut.
These components slide or snap into position (by hand) at panel edges or center-panel locations, making them ideal for blind assembly locations. They’re also a good choice for applications requiring extra-high torque and holding power.
No welding, clinching, staking, special skills, or equipment is required for installation. Another benefit: Nut retainers are rust-proof and can be applied after painting, eliminating costly masking or retaping of paint-clogged threads.
There are three main types of nut-retaining fasteners:
• Cage nuts
Cage nuts — also known as rack or captive nuts — combine a strong spring steel cage and a multi-threaded nut. They’re ideal for rack and equipment-mounting applications.
Cage nuts have spring-steel “mechanical hands” or wings that keep the nut stationary in a square hole, which helps with bolt insertion. As the nut is pressed to the locked position, the mounting legs expand around the panel and force past the retainer spring tabs, snapping back to lock the fastener firmly in place.
They can be applied at any convenient spot along the assembly line and are ideal for blind-assembly attachments. Applications include automotive, electrical, HVAC, cabinet construction, server racks, and others.
How to apply cage nuts:
1. Insert one of the cage nut’s retaining legs into the panel hole
2. Snap the other leg into the hole by hand or with a simple tool
3. Align the second panel, and then thread the bolt onto the captive nut.
4. Tighten the bolt into the self-retaining nut
5. A positive, high-torque, flush attachment is achieved
J-nut or J-type retainers combine the strength of a nut with the flexibility of a spring steel cage. They easily snap over panel edges or can be inserted into rectangular holes in central panel locations. Floating alignment and retention are attained with extrusions in the retaining legs, which snap into panel mounting holes — allowing the fastener to shift or align but not disengage.
Installing J-nut retainers does not require special tools or skills because they simply snap into place anywhere on the assembly line. They serve as a heavy-duty fasteners for blind location assemblies, including for use in the automotive, appliance, HVAC, and other industries.
How to apply J-nuts:
1. Push the J-nut into place on the panel or a rectangular hole that’s in the panel’s center
2. Snap the extrusion into the hole
3. Position the second panel and the drive screw
4. Align the panels
5. Flush-mounting is obtained by embossing either panel
U-nut or U-type retainers provide the same advantages as J-nuts. They offer a low profile and heavy-duty fastening when combined with a machine screw that’s ideal for blind location assembly. They’re self-retaining and will not turn when the screw is driven.
U-nuts maintain constant alignment with an extrusion on the lower leg. Button-hooked into center panels or pressed over flanges, they retain themselves with “mechanical hands” formed from the spring steel retainer and are held securely under live spring tension. They’re easily applied by hand or with simple tools and are used in several applications, including electronics, vending, appliances, automotive, marine, and others.
How to apply U-nuts:
1. Push the U-nut into a bolt-receiving position on the panel or in the rectangular hole in the center of the panel
2. Snap the extrusion into the mounting hole
3. Position the second panel and drive in the screw
4. Ensure flush mounting is obtained
5. Access to the back of the panel is unnecessary to complete the assembly