Our Technology

Spiralock Corporation has re-engineered the standard (female) internal thread form and added a unique 30-degree wedge ramp at the root of the thread.  This unidirectional internal thread form, called Spiralock®, mates with standard 60-degree male thread fasteners.

The wedge ramp allows the bolt to spin freely relative to the female threads until clamp load is applied.  At that point, the crests of the standard male thread form are drawn tightly against the wedge ramp, eliminating radial clearances and creating a continuous spiral line contact along the entire length of the thread engagement.  This continuous line contact spreads the clamp force more evenly over all the engaged threads, improving joint fatigue life as well as the integrity of the threaded joint.