Loctite 641 Retaining Compound(tube)

LOCTITE 641 is a medium-strength, anaerobic retaining compound designed for bonding cylindrical fitting parts in applications where future disassembly for service is anticipated. This yellow acrylic methacrylate ester adhesive is widely used for retaining bearings onto shafts and into housings, providing a balanced combination of strong mechanical retention and serviceability.

Key Features

LOCTITE 641's medium-strength formulation distinguishes it from high-strength permanent retainers — it's engineered to lock cylindrical assemblies securely against shock and vibration while still permitting controlled disassembly when maintenance is required. The one-component formula needs no mixing, has a medium viscosity (400–800 mPa·s at higher shear rates), and cures anaerobically when confined between close-fitting metal surfaces, eliminating air-dependent set times. This retaining compound performs across slip-fit, press-fit, and shrink-fit assembly methods, adapting to multiple manufacturing processes.

Performance Data

After 24 hours of cure at 22°C, LOCTITE 641 achieves compressive shear strength of ≥6.5 N/mm² on steel pins and collars. Cure speed and final strength vary with substrate (steel cures fastest, followed by aluminum, then zinc dichromate) and with bond gap, with tighter gaps (0.05 mm) curing significantly faster than wider gaps (0.2 mm). The product retains good strength through heat aging at 120°C, with more pronounced softening at 150°C over extended exposure. Chemical resistance testing shows strong retention of properties in motor oil, unleaded petrol, brake fluid, water/glycol mixtures, and ethanol, with somewhat reduced resistance in acetone at extended exposure.

Applications

LOCTITE 641 retaining compound is the standard choice for bearing-to-shaft and bearing-to-housing retention in motors, pumps, gearboxes, and rotating equipment where periodic service access is built into the maintenance schedule. It's also effective for bushings, sleeves, and other cylindrical fits in general industrial machinery. Because it allows for heat-assisted disassembly, LOCTITE 641 is preferred over high-strength alternatives whenever a component is expected to be serviced, replaced, or rebuilt over its lifecycle.

Directions for Use

Clean all bonding surfaces with a LOCTITE cleaning solvent and allow to dry before application. On inactive metals or for faster cure, spray with LOCTITE SF 7471 or SF 7649 Activator. For slip-fitted assemblies, apply adhesive around the leading edge of the pin and the inside of the collar, using a rotating motion to ensure even coverage. For press-fitted assemblies, coat both bond surfaces thoroughly and assemble at high press-on rates. For shrink-fitted assemblies, coat the pin and heat the collar to create assembly clearance. Avoid disturbing parts until adequate handling strength develops. Disassembly requires localized heating to approximately 250°C.

Why Buy From Tapemart

Tapemart stocks genuine LOCTITE 641 medium-strength retaining compound as part of our comprehensive LOCTITE retainer and bearing-mount adhesive lineup. As an authorized LOCTITE distributor, we support manufacturers and maintenance teams with the right retaining compound strength for serviceable rotating assemblies. Order LOCTITE 641 from Tapemart for reliable bearing and bushing retention that balances strength with maintainability.