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Different Types of Threaded Locking Methods for Secure Connections
I don't know if Spiralock counts as one of these technologies, but Spiralock should be more widely known. Spiralock threading puts a shoulder which is ground to a slightly different angle on the entire screw thread so the entire bolt or screw gets compressive loading along its shaft, locking it in place by friction when the screw is tightened, while still permitting easy turning until it is tightened. Finite element analysis shows that this removes the stress concentration along the top-most threads that occurs in regular screw and bolt threading.
To continue on this thought, here's a video explaining the Spiralock thread.
May I just add that the spring lock type washers mentioned here, along with all other spring type washers are not part of the DIN norms anymore because of low to zero proven effectiveness. There are however multiple other locking type washers (including the nordlocks mentioned).
Correct, spring washers are ineffective, proven since 1969.
I don't care what tests have been performed, from my own past experiences, using spring washers has never failed me. Not once. And I've been using them for more than 20 years.
I'd consider stretch bolts a type of thread locking mechanism also.
You left out locking helicoils, lock plates (where a sheet of metal is inserted below the head of the bolt and a corner is bent up against a flat of the bolt head and down over the side of the flange to prevent the bolt from backing off), and the quick and dirty, but very effective tack weld.
These are also great locking mechanisms, thank you for sharing!