Simla Ay
ADhesives: threadlocker
Technical Marketing Writer Hernon Manufacturing
How to choose the ideal threadlocker for an application?
Several different types of threadlockers are available for use, depending on the bolt materials and requirements of the application. For example, blue threadlocker is used for medium-strength assemblies and critical joints that only rarely need disassembly.
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Threadlockers are recommended for use anytime a threaded fastener will be exposed to vibration, repeated impacts, or when it’s imperative to maintain a product’s structure and function. This is because nuts and bolts often loosen due to thermal expansion, vibration, or improper torque. Although conventional mechanical fasteners, such as nuts or washers, are commonly used to keep the threads secure, mechanical devices are subject to loosening or failure over time. A chemical threadlocker is a thin, mainly anaerobic adhesive that’s
December 2021 www.fastenerengineering.com
applied to the threads of fasteners to prevent them from loosening. It fills the gap between the threads of a nut and bolt, significantly increasing the area of contact, and forming a bonded thermoset plastic seal. This seal ensures unwelcome liquids stay out of the threads and prohibit any penetration of the bolt hole. The use of threadlocker also increases the area of friction between the mated surfaces. Typically, there’s a range of about 15% metal-to-metal contact between the two (and this is where friction occurs), but the remaining 85% of the threads are not in contact. In addition to holding the assembly in place, the cured thermoset plastic provides some flexibility to tolerate thermal and cycling while offering an inert barrier that resists galvanic corrosion. Only a small drop of threadlocker is required for most applications, which is applied near the end of the male threads and away from the bolt head. As a bolt is screwed into a nut or retaining piece, the adhesive will coat the female threads. Once the fastener is fully tightened, the threads will bear down on one another, leaving a small amount of liquid threadlocker as oxygen is pushed out. This creates an anaerobic environment, given the absence of free oxygen, which triggers threadlocker curing and the threaded assemblies then lock into place. When choosing a threadlocker, the most important considerations are the: DESIGN WORLD
