Let’s Talk About-Threadlocker’s
If you are using glue in Ireland, or abroad, no matter what the application, gluing metal, gluing plastic or gluing wood, correct information is vital.
The ‘Lets Talk About’ is a new series which discusses in brief, some of the in’s and out’s of various types of glue families. In the first in the series, we will talk about thread-lockers.
We have all heard of them, but do we know what they are? What are threadlocker’s, how do they work and what are they used for…..all will be revealed!
What are they?
They are all single component (no mixing needed) adhesive, applied to the threads of fasteners such as screws and bolts to prevent loosening, leakage, and corrosion. They are especially important in mechanisms that are exposed to movement and especially vibration.
How do they work?
Anaerobic thread locking adhesives need two things to cure. The first thing is a lack of oxygen. Adhesives which cure in a near to oxygen free environment are referred to as anaerobic adhesives. Second,they need to be in contact with a metal surface. The metal surface creates electrochemical activity, which the anaerobic glue needs to assist it in curing.
Combining the oxygen free environment & contact with the metal surface, causes the anaerobic threadlocker to cure. Be careful, both oil and dirt on the surface of the parts, creates a film that will limit the ability of the adhesive to bond as well as cure; therefore, thorough cleaning of the contaminated parts will always be necessary. In addition, the application of a primer may be required on substrates that exhibit lower ionic activity such as aluminum. Cleaning and priming the parts adds considerable cost and production time to many assembly applications, therefore, threaded fittings should be kept clean and stored in their original supply box
How are they used?
Depending on the specific type of threadlocker and the exact application for which it will be used, all thread-lockers may be applied either before or after assembly. Generally speaking, threadlocker’s are available in three different strengths.
First we have the high strength permanent types. These are designed for applications where the threaded fitting must never come loose of where there will never be a need to remove the threaded fitting, i.e., for maintenance. Next we have medium strength types. These are designed for applications where the threaded fitting may need to be opened, for example, inspection or maintenance. The third type are low strength removable types. As the name suggests, these types offer extra security for a threaded fitting but they can be opened reasonably easily.
There are typically a few variations of each of the three types. The difference centres on the thickness or viscosity of the threadlocker. As an example, long, narrow threads with a very narrow pitch (pitch is the distance from the crest of one thread to the next), need a low viscosity (thin) threadlocker, thus allowing the threadlocker to flow into the tight threads. Course threads, with a correspondingly larger pitch, need a threadlocker which has a higher viscosity (thick).
Using them practically is reasonably straight forward. Don’t forget, the surfaces should be clean and dry!
1. For open holes, apply a few small drops of the threadlocker onto the bolt, in the area where the nut will finally engage.
2. For closed (blind) holes, apply a few small drops of threadlocker to the lower third of the internal threads within the closed hole. Alternatively, it is possible to place a few drops into the bottom of the hole.
What are the key points to remember?
1. Remember we said that threadlocker’s work in an oxygen free environment? The nut & bolt must fit each other perfectly. Using threaded fittings with different thread sizes will not allow the threads to seal properly and allow the entry of oxygen.
2. If you decant the threadlocker into a smaller vessel, to allow for dipping threaded bolts etc, don’t pour any unused threadlocker back into the original stock (supply) bottle. Metal particles in the smaller vessel, will cause the threadlocker in the supply bottle, to cure.
3. If using the threadlocker from its original supply bottle, don’t allow the tip of the bottle to physically touch the metal surface of the fitting. Again, it may become contaminated with metal filings, and cause the nozzle to clog.
4. Finally, we never suggest the use of so called activators or kickers, to speed up the speed of cure of the adhesive. Activators cause the adhesive to cure prematurely with a noticeable reduction in strength.
We offer a range of locally manufactured threadlocker’s, which satisfy most requirements.