“ At first sight, Huck 360®
lockbolt looks very much like
a conventional threaded bolt and nut combination. In fact, there are very significant technical and even more significant performance differences.”
differences. For Alcoa Fastening Systems’ development team, the goal was simple – to design a high strength bolting system that resists vibration loosening no matter how extreme the environment, delivers superior fatigue strength, and holds tight under high cyclic fatigue loads. And just to add to the challenge, it must also be capable of rapid installation and removal using conventional tooling. Jonathan Craven, AFS Telford operations director, explains
how Alcoa Fastening Systems’ ingrained instinct for effective innovation has delivered a new product with unique capabilities. “Huck 360 lockbolt has a shallow proprietary thread form that
concentrates 27% less axial stress in the root than conventional bolt threads. This stress concentration is the primary contributing factor leading to stress corrosion cracking and fatigue failures. Huck 360 lockbolt’s thread flanks are effectively locked preventing the nut from moving relative to the bolt – in contrast to a conventional threaded bolt where thread flanks are able to slide when subjected to transverse vibration, resulting in the nut
moving relative to the bolt.” “Additionally, when the Huck 360 lockbolt nut is tightened, it
plastically deforms around the thread. The resultant intimate contact is circumferential, helping to generate vibration resistance previously only achievable by using a lockbolt.” Huck 360 lockbolt nuts can be simply hand spun onto the bolt
unlike conventional lock nuts where prevailing torque requires almost immediate use of a tool. This significantly speeds up assembly times, with final setting carried out with a conventional torque wrench. An assembly speed comparison video at
www.huck360.com provides an excellent visual demonstration. “We recognise that the rail track sector is understandably
extremely cautious in assessing new product developments for safety critical applications,” says Jonathan Craven. “We are confident that, as engineers are able to assess first hand the capabilities of the Huck 360 lockbolt, it will gain approval and come to make a very substantial contribution to rail safety, efficiency, and economics.”
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