How To Select The Right Retaining Compound

Advantages of Retaining Compounds

Applied as a liquid, they fill surface irregularities and provide 100% contact between mating metal surfaces, eliminating the need for expensive replacement parts, time consuming machining, or the use of mechanical methods. In addition, retaining compounds offer high strength with simplified and less costly designs, and reduced dependence on machining tolerances. They eliminate corrosion and fretting, and improve the durability of assembly. They offer the ability to disassemble the component, and an even distribution of load and stress over the entire joint.

What is the difference between a Retaining Compound and a Threadlocker?

This question ultimately comes back to the application at hand and the substrate the adhesive is being used on.

Retaining compounds are typically higher strength and designed specifically for bonding cylindrical components that must resist usually torque and compressive loads. 

Threadlockers, however, are designed to prevent self-loosening, leakage, and corrosion of threaded fasteners. Choosing the correct type of adhesive is crucial within aerospace, automotive, rail, and heavy machinery applications, but when high strength bonding is required, retaining compounds are generally the right choice.

Three factors need to be considered when selecting a retaining compound for a particular application.

Gap Fill Requirements

Like other anaerobic adhesives in the Loctite portfolio, retaining compounds are designed to fill small gaps and surface irregularities. Loctite retaining compounds are available in a range of viscosities, with some specialist grades capable of filling gaps up to 0.5mm:

• Gap Size – up to 0.15mm – typically lower viscosity products
• Gap Size – between 0.15mm and 0.25mm – higher viscosity liquid products
• Gap Size – between 0.25mm and 0.5mm – paste like products, possibly used with activator

Strength Requirements

Similarly to threadlockers, retaining compounds offer both high strength (for permanent bonds) and medium strength (for future disassembly). High strength retaining compounds offer a higher shear and compressive strength and can also be used in applications with high torsional loads.

Service Temperature Requirements

Most Loctite retaining compounds offer a service temperature range between -55°C and 150°C. However, certain products are able to withstand higher temperatures (between 180°C and 230°C) for applications subject to more extreme heat.