The need to secure an insert with glue is dependent on the application and the insert and some varieties of insert will even specify the use of glue. It may also be beneficial to glue inserts which will be subject to heavy use.
There is a speciality glue called ‘thread-locking adhesive’, which is for securing all threaded items. This can be applied to the external surface of threaded inserts to secure their position when installed.
Thread-locking adhesive works anaerobically, which means without oxygen. Therefore, the thread lock begins to work as soon as the threaded item is installed and hidden from the atmosphere.Thread lock is completely liquid when in contact with the atmosphere and so only the parts which interlock will set. This means the adhesive can be applied to the insert, will not seize up when installing and any excess which gathers can simply be wiped away.
There are different strengths of thread lock, which are usually distinguished by colour. Thread lock is designed to be permanent, but there are techniques to remove it, usually involving the application of heat.The range of thread-locking adhesives usually follows the scale purple-blue-red-green, with purple being low strength, red being high strength and green being penetrating.
Some varieties of solid insert are now available with thread lock pre-applied. This is possible because the thread lock only begins to work in anaerobic conditions, so once the insert is installed, the thread lock is activated.
There is an epoxy alternative to thread lock, which is thought by some to be stronger.Epoxy is a more permanent solution as there is no removal process without damaging threads. Epoxy adhesives are available for use on plastic and wood applications and will fill gaps between insert and application materials, reducing the need for accurate fitting, which is suitable for wood and plastic.