LOCTITE 641

Harmonization Code : 3907.30.00.40 | Epoxy Mold Compounds containing by weight more than 70 % silicon dioxide

LOCTITE 641 LOCTITE 641 LOCTITE 641 LOCTITE 641

Main features

  • Serviceable Medium-Strength Retention
  • Controlled Medium-Viscosity Flow
  • Anaerobic One-Part Metal Cure

Product Description

LOCTITE 641 is a yellow, medium-viscosity one-component anaerobic retaining compound for cylindrical metal parts that may require later service disassembly. It cures between close-fitting metal surfaces after air is excluded and is commonly used to retain bearings on shafts or in housings. The shear-thinning viscosity profile supports controlled coverage during assembly. After 24 hours at 22 deg C, the cured compound develops at least 6.5 N/mm^2 compressive-shear strength on steel pins and collars. Medium-strength retention balances secure positioning with removal using appropriate service methods.

Key features

  • Serviceable medium-strength retention: The cured joint retains cylindrical parts while supporting later disassembly with appropriate methods.
  • Controlled medium-viscosity flow: Brookfield viscosity data support coverage without excessive run-off during assembly.
  • Anaerobic one-part processing: The compound cures in confined metal fits without mixing.

Applications / Suitable for

  • Retaining bearings on shafts
  • Retaining bearings in housings
  • Bonding cylindrical metal parts requiring service disassembly
Product Family

LOCTITE 641

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TDS, SDS & Technical Documents

Technical Specifications

General Properties
Chemistry Type
Methacrylate ester
Color
The color
Yellow liquid
Component System
Describes the number of components that must be supplied, mixed, or activated before application or cure.
One component
Specific Gravity
Specific gravity (SG) is the ratio of the density of a substance to the density of a reference substance; equivalently, it is the ratio of the mass of a substance to the mass of a reference substance for the same given volume. For liquids, the reference substance is almost always water (1), while for gases, it is air (1.18) at room temperature. Specific gravity is unitless.
1.07
Thermal Properties
Linear thermal expansion
80×10^-6 K -1
Specific Heat Capacity
Specific heat capacity is the amount of heat energy required to raise the temperature of a substance per unit of mass. The specific heat capacity of a material is a physical property. It is also an example of an extensive property since its value is proportional to the size of the system being examined.
0.3 J/(g⋅°C)
Thermal Conductivity
Thermal conductivity describes the ability of a material to conduct heat. It is required by power packages in order to dissipate heat and maintain stable electrical performance. Thermal conductivity units are [W/(m K)] in the SI system and [Btu/(hr ft °F)] in the Imperial system.
0.1 W/m.K
Physical Properties
Viscosity
Viscosity is a measurement of a fluid’s resistance to flow. Viscosity is commonly measured in centiPoise (cP). One cP is defined as the viscosity of water and all other viscosities are derived from this base. MPa is another common unit with a 1:1 conversion to cP. A product like honey would have a much higher viscosity -around 10,000 cPs- compared to water. As a result, honey would flow much slower out of a tipped glass than water would. The viscosity of a material can be decreased with an increase in temperature in order to better suit an application
400 to 800 mPa.s

Additional Information

Technical properties

As-supplied / before-processing properties

Typical values and characteristics for the product before cure, application, or assembly.

PropertyValueUnitMethod / condition
AppearanceYellow liquid-As supplied
Chemical typeMethacrylate ester-One-component material
Specific gravity1.07-25 deg C
Viscosity1,215 to 2,750mPa sBrookfield RVT, spindle 2, 2.5 rpm, 25 deg C
Viscosity400 to 800mPa sBrookfield RVT, spindle 2, 20 rpm, 25 deg C
Viscosity90 to 180mPa sEN 12092-MV, 277 s^-1, 25 deg C
Cure mechanismAnaerobic-Confined between close-fitting metal surfaces
Technical properties

After-processing / final-state properties

Typical values for the cured, bonded, treated, or in-service product under the listed conditions.

PropertyValueUnitMethod / condition
Compressive shear strength>=6.5N/mm^2Steel pins and collars, cured 24 h at 22 deg C
Coefficient of thermal expansion80 x 10^-6K^-1Cured material
Thermal conductivity0.1W/(m K)Cured material
Specific heat0.3kJ/(kg K)Cured material

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