Self-loosening of metal screw joint bolts is one of the key reasons mechanical assemblies fail
Self-loosening of metal screw joint bolts is one of the key reasons mechanical assemblies fail.
In certain applications, such as automotive, this is an outcome which could lead to catastrophic equipment failure and potential loss of human life. Any number of factors can contribute to a loss of bolt tension – changes in temperature, poorly fitting parts, vibration or insufficient clamp loads. These load changes produce short-term frictionless situations where the bolt unwinds from the nut and eventually leads to a relaxation of tension in the threaded assembly.
Finding a solution to this issue is what drove the founder of Loctite, Vernon K. Krieble, to experiment with chemical threadlocking adhesives. He patented a threadlocking fluid technology which cured only in the absence of air – in other words, when the fastener is applied and maximum torque is attained. The anaerobic adhesive acts like a lock, filling every available space between the thread and the nut.
Chemical threadlocking adhesives can also be epoxy-based, characterised by extremely strong bonds and resistance to heat and chemicals, but they need to be mixed with a hardener in order to cure. Mechanical threadlockers such as nylon increase friction between the mating threads, and require a higher installation torque, but generally are only about 50% as strong as chemical threadlocking products. Other common thread treatments include thread sealants and anti-seize compounds.
Even if removal of the part is required during its lifetime, a chemical threadlocker could still be used, such as Loctite 222. The incredible spectrum of applications in which Loctite threadlocking adhesive is employed underlines its universal appeal and the degree to which the brand is seen as the definitive threadlocking solution – from securing the bolts of the Crossrail tunnel boring machines to the fittings of La Cornue ovens and the hydraulic pipes of Berg propellers.
Depending on what is the most important consideration for the user, Loctite can offer a range of threadlocking options.
Does your bond need to with stand high temperatures?
Do you need to remove the adhered joint at any time?
Does the bond have to be permanent?
Is wicking of the adhesive important?
Using our Loctite solution selector can help you find the particular grade that is most suitable. A pioneer in threadlocking adhesive, Loctite continues to develop its product range to deal with new applications.