Products
Threadlocker vs retaining compound: which one, where?
Use a threadlocker on threaded fasteners, such as bolts, nuts, studs and screws, to stop them loosening. Use a retaining compound on cylindrical fits without threads, such as bearings, bushes, gears and pulleys on shafts, to stop parts slipping or spinning. Both are anaerobic adhesives, but each is made for a different joint shape, gap and load.
By S. Sakthi Kumar, industrial adhesives & sealants consultant · · 3 min read
Same chemistry, different job
Threadlockers and retaining compounds are both anaerobic adhesives. They stay liquid in air and cure once trapped between metal surfaces, away from air. The difference is in what they are formulated to do.
A threadlocker is made to fill thread clearances and resist the vibration and torque that loosen fasteners. A retaining compound is made to fill the gap between cylindrical parts and carry load in shear across a much larger surface, which also stops fretting corrosion.
Side by side
| Threadlocker | Retaining compound | |
|---|---|---|
| Joint | Threaded fasteners | Cylindrical fits |
| Main job | Stop loosening, seal threads | Stop slipping and spinning, fill gaps |
| Load | Vibration and torque | Shear, axial and torque |
| Examples | Gearbox bolts, motor mounts, studs, set screws | Bearings in housings, bushes, gears and pulleys on shafts |
| Removal | Hand tools to local heat, by strength grade | Pullers to local heat, by strength grade |
Common mix-ups
- Threadlocker on a bearing. It may hold for a while, but it is not formulated for that gap and load. A retaining compound gives reliable strength.
- Retaining compound on bolts. It will cure, often far stronger than needed, and removal may need heat.
- High strength everywhere. Maintenance teams then struggle to open parts. Match strength to how often the joint is opened.
- Skipping cleaning. Oil weakens both. Clean parts, and use an activator on stainless steel and plated parts.
Choosing within each family
For threadlockers, the choice is mainly strength: low, medium or high, plus wicking grades for parts already assembled. See threadlockers.
For retaining compounds, the choice is mainly gap and strength: standard grades for close fits, high-gap grades for worn housings, and high-temperature grades where needed. See retaining compounds.
Shop-floor tips
- Clean and dry the parts first.
- Threadlocker goes on the bolt threads where the nut will engage, not on the first thread only.
- For retaining compounds, follow the data sheet on which surfaces to coat, especially for press fits.
- Let the adhesive cure before loading the joint. The data sheet gives fixture and full-cure times.
- Keep a small standard set in stores so people do not grab the wrong bottle.
For brands and dealers
In maintenance stores, these two products are the easiest adhesive products to demonstrate and the quickest to show a saving. They are often the best way into a new plant. If you sell them, see how I can help with business development.
Questions people ask
Can I use a threadlocker to fix a bearing?
In an emergency it may hold, but threadlockers are not formulated for cylindrical fits. A retaining compound gives reliable strength and gap filling for bearings, bushes and shafts.
Can I use a retaining compound on threads?
It will cure, but usually much stronger than needed, which makes later removal hard and may need heat. Use a threadlocker of the right strength instead.
Which is stronger, threadlocker or retaining compound?
It depends on the grade. High-strength versions of both are very strong. Compare data sheet values for the same type of joint rather than comparing the families in general.