Chemical threadlockers really are the best

Although no longer a new science, chemically locking nuts and bolts remains misunderstood by many engineers and a closed book for some.
      Yet no matter where in the world the engineer is or what he (or she) is bolting together, this is the simplest and most effective method of ensuring that what’s done up remains done up – until it needs to be undone.
      Chemical threadlockers are room temperature curing liquids that use anaerobic technology – and like all technologies, it has been developed over the years so that the latest forms, mostly from newer brands (such as AJett) looking for product advantage, are less wasteful and can be applied successfully to ‘as received’ parts, including those coated with a protective oily film.

Why use a threadlocker?  
Well, traditionally, locking bolts relied on tightening the joint as much as possible and using a washer.  Difficult applications used castellated nuts and cotter pins, plastic patches on bolts, aircraft-type locknuts and all manner of washer styles – all of which are high on inventory and production line costs.
      Why go to this expense and trouble when standard, plain, nuts and bolts and a bottle of threadlocker will do the job far more effectively?  They provide 100 per cent of the locking power and do not require special torquing-up.
      This makes them cheap and easy to apply, yet are more reliable than any other form of locking device – to the point where washers, plain or fancy, are unnecessary.

Some benefits
Vibration is the enemy of any nut/bolt combination, unsettling and then loosening them, while rust-lock is the bane of the maintenance engineer’s life.
      Anaerobics seal against leakage, corrosion and vibration and resist common chemicals and solvents, so even after years of reliable service, nuts and bolts can be undone without destroying them.
      Normally, only a few drops are required, either via an automated applicator or directly from the manufacturer’s original bottle, hand held.
      Unless a particularly high strength threadlocker is used, all can be undone with hand tools.

How they work
Threadlockers work by filling the thread engagement area as a liquid, wetting all the surfaces, taking up new spaces when threads are tightened and polymerising due to the combination of contact with metal and the absence of oxygen.
      They cure into a tough, hard thermoset plastic, with cross linked molecule chains for extra toughness, to bond the thread flanks together.
      Adhesion is highest on close fitting torqued threads and perfectly satisfactory on course, untorqued threads.
      Excess, uncured threadlocker can be wiped off.  Primers will speed cure times on plated parts and low temperature applications, and enable some plastic threads to be locked.

Uses
Chemical threadlockers can be used on any type of nut, bolt, stud and machine screw as well as tapped holes, speciality threaded components and machine cut threads, no matter what the size or thread style.
      Handling strength is normally 30 minutes, but this can vary according to the grade chosen or to suit production requirements.
      Similarly, temperature resistance is normally -50 to +150°C, but grades for use outside these temperatures are available.  Strength is measured as breakaway torque (the initial movement) or prevail, the average value of the first full turn torque.
      Low strength threadlockers, used for precision screw and set screws that need adjusting, have breakaway torques of up to 9 N.m; medium strength, for almost all general threadlocking duties, will breakaway from 10 to 25 N.m; while high strength threadlockers, for permanently holding studs in place while nuts are removed or to remove stress points with free running studs, have breakaway torques of 15 to 35 N.m.

Grand Prix
Threadlocking with chemicals has been described as at best essential – but at worst the best insurance policy you can have.
      It is commonly used in all classes of motor racing, with some Grand Prix teams even sending cars out during practice with a few drops of threadlocker on finger tightened nuts and bolts, such is their faith in chemical threadlockers and the need to save fractions of seconds – weight, too, as washers are unnecessary.
      Can there be a better example to other engineers?
      They should also feel reassured that because threadlocking is not a new science – it dates back to the early 1950s – they have nothing to fear but an awful lot to gain.

Advanced Adhesives (UK) Limited
Chater Lea Buildings, Icknield Way,
Letchworth, SG6 1EZ, England

Phone  UK  01462 677060
Fax  UK  01462 677070

Phone  International  +44 146 26 77 060
Fax  International  +44 146 26 77 070

E-mail  info@ajett.com
Web  www.ajett.com

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