Loctite 641 Retaining Compound 50ml

Loctite 641 is a one-component, yellow, medium strength anaerobic retaining compound. It is a methacrylate ester that cures anaerobically, so there is no mixing.

It retains cylindrical fitting parts, especially where the assembly has to be taken apart for service. Where cure is slow or the gap is large, an activator speeds it up.

Where this product is used

• Cylindrical fitting parts that need disassembly for service
• Assemblies where cure is slow or the bond gap is large (activator recommended)
• Parts exposed to motor oil, unleaded petrol, brake fluid or water/glycol
• Assemblies that can be released with localised heat to about 250 °C

Features

• Medium strength, for parts that need disassembly for service
• One component, no mixing
• Yellow liquid, fluorescence negative, so it cannot be checked under UV light
• Anaerobic cure, with activator as the secondary cure
• Retains about 90 % of initial strength after 1,000 hours in motor oil at 125 °C
• Retains 100 % of initial strength after 1,000 hours in brake fluid at 22 °C
• Hot strength tested from 0 to 150 °C, heat ageing tested at 120 and 150 °C

Key specifications

Choosing the right option

Loctite 641 is the medium strength grade, for parts that have to come apart again. For high strength retaining compound see Loctite 680 High Strength Retaining Compound 50ml, or Loctite 648 High Strength, High Temperature Retaining Compound 50ml for a high strength grade, which offers high temperature performance.

Where cure is slow or gaps are large, see Loctite 7471 Primer T Surface Preparation Activator Aerosol 133g and Loctite SF 7649 Activator for Anaerobic Adhesives 133ml.

See also: Loctite 638 Retaining Compound 50ml, Loctite 680 High Strength Retaining Compound 50ml, Loctite 648 High Strength, High Temperature Retaining Compound 50ml, Loctite 7471 Primer T Surface Preparation Activator Aerosol 133g.

Using it

Parts should not be disturbed until sufficient handling strength is achieved. Cure speed depends on the materials, the gap and the temperature. Test gaps of 0.05, 0.15 and 0.2mm on steel pins and collars.

Where cure is slow or the gap is large, use Activator SF 7471 or SF 7649.

To disassemble, apply localised heat to about 250 °C and take the parts apart while hot.

Storage and handling

Store unopened in a dry location, optimally between 8 °C and 21 °C. Storage below 8 °C or above 28 °C can adversely affect the properties of the product.

Limits and safety

Not recommended for pure oxygen or oxygen-rich systems, or as a sealant for chlorine or other strong oxidisers. Not recommended on plastics, particularly thermoplastics. Check compatibility with aqueous washing systems.

Cure speed depends on the materials, the gap and the temperature, and the cure-speed graphs are in the data sheet.