Retaining compounds
Retaining compounds are anaerobic adhesives used to secure cylindrical fitting parts such as bearings, bushings, shafts, sleeves, gears and pulleys. They cure when confined between close-fitting metal surfaces, helping prevent movement, loosening and leakage caused by shock, vibration and operating loads.
LOCTITE® retaining compounds are widely used in automotive, heavy machinery and metal-to-metal applications. They can reduce the need for excessive machining during maintenance and repair, help prevent fretting corrosion and reduce wear.
Types of retaining compounds
LOCTITE® retaining compounds can be selected by application, strength, temperature capability, viscosity, fit and gap-filling performance. These characteristics overlap, so the complete application requirements should be considered rather than a single label.
Bearing retaining compounds
Bearing retaining compounds are designed to secure compatible bearings in housings or on shafts. Key considerations include:
- Bearing-to-shaft or bearing-to-housing fit
- Clearance and gap size
- Press-fit, interference-fit or slip-fit assemblies
- Oil contamination or oil-impregnated components
- Required holding strength
- Removal and maintenance requirements
High-strength retaining compounds
High-strength retaining compounds resist movement between cylindrical parts after curing. They can be suitable for shafts, gears, pulleys, bearings, bushings, sleeves and other load-transmitting assemblies exposed to shock or vibration.
High strength is not always the best choice. Where components need to be removed for maintenance, a lower-strength or serviceable product may be more appropriate.
High-temperature retaining compounds
High-temperature retaining compounds are selected according to their operating-temperature capability. Temperature resistance is product-specific and separate from bond strength. For example, LOCTITE® 638 is specified for temperatures up to 180°C, while LOCTITE® 620 is specified for applications up to 232°C. Always check the relevant technical documentation for maximum continuous and peak temperatures.
Retaining compound vs. threadlocker
The main difference between retaining compounds and threadlockers is the type of joint they secure:
- Retaining compounds are primarily formulated for cylindrical fitting parts such as bearings, shafts, bushings, sleeves and gears.
- Threadlockers are formulated for threaded fasteners and help prevent loosening caused by vibration.
They should not be selected interchangeably because joint geometry, clearance, load and disassembly requirements differ. Select the product according to the joint design, operating conditions and required performance.