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What even is a lockbolt?




The original lockbolt was developed as an alternative to the conventional bolt and nut combinations, which exhibited some severe weaknesses. These included loss of preload under service load; setting and relaxation effects in thread; self-loosening effects under vibration load; and relative movement in the thread bearing area.


Accufast Inc has been selling lockbolts across Western Canada for 30+ years and we are proud to be a Master Distributor with an In house repair facility, trained experts on tooling, and technical sales reps with many years of experience in providing vibration resistant solutions for the manufacturing industry.

The traditional lockbolt was able to combat these problems and consistently provide a secure locking system. For instance, the lockbolt has a special locking groove design that provides vibration resistance and extreme fatigue life. This is due to a larger cross-sectional area and no stress concentration. When compared, a 3/4 "lockbolt has 18% more bolt cross sectional area than a 3/4" standard bolt. Lockbolts also have a larger core diameter than regular bolts. Using a nut and screw there is only 30% – 35% contact and the applications is vibration sensitive.

When it comes to the self-loosening effect under vibration load we are all aware of the Junker test, which monitors a bolted joint as it loses its preload when subjected to shear loading caused by transverse vibration. Compared to conventional bolts and nuts, lockbolts demonstrate superior vibration resistance due to the innovative design. They have no relative movement in the thread bearing area which leads to a much longer life and minimal upkeep! NO MORE RE TORQUING!

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 follows the form of annular grooves. During installation this collar is mechanically ‘swaged’ permanently with an installation tool.

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.

Over the years the lockbolt fastener has evolved into newer styles such as the G-Grip which is the first polished stainless multigrip lockbolt availible on the market. We also are able to offer a wide range of head styles to ensure your manufactured projects are strong, dependable, and dont shake loose.





At Accufast Inc we consistently provide quality vibration resistant fastening options throughout Alberta, Saskatchewan, and British Columbia. Contact one of our knowledgeable technical sales reps today to see how you can make your design outlast the rest by using the best structural fastening solutions on the market.

Call us at 780-436-7400. We look forwards to helping you succeed. I hope this informative article will help you in your design, and help you create innovative products to drive change in the manufacturing industry.

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