Fasteners combat the effects of vibration

There are quite a few reasons why threaded fasteners experience self-loosening, but generally it’s that there isn’t sufficient clamp force present on the joint interface to prevent movement between the bolt head or nut and the joint.

Transversely applied alternating forces, also known as vibration, generate the most severe conditions for self-loosening. Firstly, the joining materials slip, the threaded fastener’s friction is then reduced on the surface of the material it’s joining, then torque acting on the fastener coupled with the vibration (Jost Effect) results in self-loosening occurring.

Huck LockBolt and structural blind fasteners from Star Fasteners are designed to provide permanent, vibration-resistant, superior-quality joining solutions for use in industrial applications. Huck fasteners offer relatively high tensile, shear and clamp properties they are suited to applications where the joints are integral to the structure.

Offering a clean and safe alternative to welding and a more efficient fastening method than standard nuts and bolts, Huck fasteners offer benefits which other fastening methods cannot, including quick and easy installation, elimination of re-checking / replacement, and ultimately cost reductions.

HuckBolts are a two-piece fastening system made up of a pin and collar. Huck Lockbolt technology works on a different principle to regular bolting, where instead of a threaded nut, a cylindrical ‘collar’ with a smooth internal bore is used. The collar is placed over a pin with locking grooves that either follow the form of annular grooves or a special form helical thread. During installation this collar is ‘swaged’ permanently.

The Huck structural blind fastener range is said to have excellent gap pull-out and high retained clamp. The tensile strength of structural blind fasteners differs to that of Lockbolt’s, as they form a blind side positive lock either by bulbing or expanding of the sleeve. The sleeve, assisted by the permanently secured pin, therefore resists failure.

This joining process offers a number of significant advantages over regular bolting. The joint is maintenance free as once the collar is ‘swaged’, it will not loosen under vibration. This provides major savings in labour costs by eliminating the need to re-torque bolts periodically in order to ensure joint integrity. The major safety benefit is that the joint is guaranteed to maintain clamp and not become compromised over time. HuckBolts can be effectively used with virtually any metal, and dissimilar metals with dissimilar coefficients of thermal expansion present no problems. Varying material thicknesses in a joint are readily accommodated, and surface finishes are not damaged.

Most importantly, HuckBolts are proven to hold up over years of service in demanding high-stress, high-vibration environments. Industries using HuckBolts include heavy-duty trucks, commercial vehicles, their chassis and trailers, rail track, crossings, railcar and locomotives, agricultural equipment and implements, aerospace, mining shaker screens and shaft construction, defence vehicles and oilfield equipment – some really challenging fastening applications.

Over the years the Huck Lockbolt fastener range has evolved. The traditional C6L and C50L Lockbolt has advanced to an innovative pintail-less design of the Huck BobTail. It is said to offer up to 10 times the fatigue strength of conventional nuts and bolts, and delivers ultimate strength, installation speed and vibration resistance. In addition, the pintail-less design of the BobTail means that there is a reduction in noise during installation, there is no waste through breaking of the pin and there is an improvement in corrosion resistance by eliminating the exposed surface resulting from the pintail break.