What is a Lockbolt or Lock Bolt (Pin & Collar)?

What are Lockbolts (or Lock Bolts) and What are they Used for?

When you think about a bolt, you think about a typical setup of a bolt and nut to secure an application. What if the elements you’re securing together have massive vibration? Enter the Lockbolt, a two-piece ribbed pin and collar fastening system! Instances where a torqued bolt and nut could be used to secure materials together but would easily come loose from heavy vibrations are perfect for Lock bolts! While welding the bolt and nut together may seem like a reasonable solution, it is unnecessary; Lockbolts are a proven alternative to welding. Consider Lockbolts for safe, simple, speedy, and cost saving installation.

The difference between using a nut and bolt versus a Lock Bolt is in the details.

• NUT AND BOLT: A nut screws onto a bolt using the matching formed or machined helix threads, and with only the initial torque being applied from the installation tightening using a wrench, the mating nut could become loose over time due to vibration or other elemental factors.

• LOCKBOLT: A Lockbolt uses a grooved pin (the groves like machined threads, but they are not, they are grooves), the grooves better assure direct and permanenting mating to the female receiving collar. The collar is placed over the pin grooves, then “squeezed” into the formed grooves. This is a simple install, and provides reliable/permanent structural integrity, the collar will not vibrate off the grooved pin.

How to Install a Lockbolt Collar (2 pieces into 1 piece)

Starting with a pre-drilled hole in the materials, the grooved pin (grooved bolt) is inserted into the hole, and collar is slid over the grooved pin. As the pin is pulled, the collar is pressed to the grooved body of the bolt with a special installation tool. This installation forms a strong, permanent bond as the locking grooves are created between the pin and collar. During the installation process, the collar is ‘swaged’ permanently. ‘Swage’ is a term used to describe bending or shaping of a component with the help of a tool, typically used in the metalworking industry when describing how to shape a metal component. In this case, the bolt grooves and the collar are swaged together using specialized tooling, available from Rivet Nut USA!

Similar forms of a collar/pin system are:

• RivetKing® Collar Bolt™ Multi Grip or Fixed Grip systems (Rivet Nut USA sells these!)
• Goebel® Goebel G-Grip Lockbolt™ Collar (Rivet Nut USA sells these!)
• Huck® Hucktainer® lock bolts, ® Magna-Grip® lock bolts, Huck® C6L® lock bolts, Huck® C50L lock bolts, Huck® BobTail® lock bolts, and Huck® Huckguard® lock bolts

Why do Lock Bolts Exist?

The Lock Bolt was developed to permanently “lock the bolt down” so that it has a high resistance to vibrations, preventing self-loosening effects and relative movement in the thread area. Your commonplace nut and bolt applications are considered not strong enough to stay secure and would loosen if the load of the application had vibration.

Lock Bolts to have a larger core diameter than basic bolts, which assists with fatigue life and helps fight against one of the most common methods of fastener failure: inadequate tension and clamping force after installation, a common pitfall of the basic nut/bolt setup. For industry-leading vibration resistance, you can’t go wrong with a lock bolt (pin and collar) system.

Collars for Lock Bolts vs Threaded Nuts of Machined Bolts

The main feature and difference between a lockbolt system and other fastening systems are the collars – the collar is the other half of the Lockbolt system that secures the pin! Collars can come in to match your hardware and your particular application.  Collars are smooth on the inside bore, while nuts are threaded on the inside bore. Rivet Nut USA has partnered with quality suppliers for a range of solutions to your application needs. Lock Bolt collars mate into pins for firm bonds and tight seals when fastened together under the Lockbolt system.

Break-pins

If you choose to use Lockbolts with break pins, the extra length of the pin (i.e., the “pintail”, or the part of the pin not securing anything) is ejected upon successful installation. The spent pintail is either collected by the installation tooling (typically when used in automation) or it falls to the floor. There is usually a section on the pin with a reduced diameter to ensure a clean, consistent break point. Multi-grip Lockbolts offer several breakpoints to offer the best length for your particular application thickness.

Once the collar is swaged/pulled onto the pin, the break occurs on the pin as the collar sets. Specialized install tooling performs this extremely efficient process with fast installation speed.

Without Break-pins

If the extra length of the pin is desired, then try a Lockbolt without break-pins. The extra length will remain, which could prove useful in your application.

Reinforced Panels

Lockbolts for reinforced panels, particularly for FRP (Fiberglass Reinforced Plywood) are designed for FRP and composite panel applications. These two-piece quality specialty fasteners install with a consistent pressure, reducing the possibility for crushing or damaging FRP panels. They are designed so you don’t have to worry about over or under tightening (ideal for FRP vehicle panels). Some valuable features that could be designed into your Lockbolt include: high shear strength for strong joint integrity, a seal that wraps around under the head for waterproofing, a strong vibration resistant joint, and color matching the head to match it’s parent application color.

Typical FRP Bolts Assembly Applications Include:

• Commercial Vehicles
• Container
• Partitioning

Common Applications for Lockbolts:

• Transportation
• Automotive applications
• Aerospace
• Lighting
• Medical equipment
• Wind turbines
• Agricultural equipment
• Metal fabrication
• Construction equipment
• Bridges and tunnels

Rivet Nut USA, a division of Cardinal Components, is your preferred Collar Lockbolt or Lock Bolt Fastener distributor, sourced from the industry’s leading suppliers. Unified/Standard and metric sizes available, in-stock, and ready to ship. Contact us today!

Photo Credit: Goebel Fasteners Inc.