loctite 641

Loctite 641

Loctite 641 Datasheet

Color:Yellow
Fixture time:20.0 min.
Gap fill:0.15 mm
Key characteristics:Strength: medium strength
Operating temperature:-55.0 °C – 150.0 °C (-65.0 °F – 300.0 °F)
Recommended for use with:Metal: steel
Shear strength, Steel:12.0 N/mm² (1700.0 psi)
Viscosity:600.0 mPa·s (cP)

Product Overview

LOCTITE 641 Retaining Compound is a medium-strength anaerobic adhesive designed for the bonding of cylindrical fitting parts, such as bearings, bushings, and sleeves. It provides reliable retention while still allowing for disassembly and maintenance when required.

Formulated to cure in the absence of air between close-fitting metal surfaces, LOCTITE 641 prevents loosening and leakage caused by vibration, shock, or thermal cycling. It’s ideal for assemblies that require a controlled strength bond—secure enough for performance, yet serviceable under proper conditions.

Key Features & Benefits

  • Medium Strength Formula – Allows for disassembly and part replacement during maintenance.

  • Vibration & Shock Resistance – Prevents loosening or fretting under dynamic loads.

  • Excellent Metal Bonding – Suitable for steel, aluminum, and other active or passive metals.

  • Activator Compatible – Use with LOCTITE SF 7471 or 7649 for faster cure on inactive metals.

  • Reliable in Temperature Extremes – Performs from –55 °C to +150 °C.

  • Controlled Viscosity – Medium-low viscosity allows easy application into tight gaps.

  • Easy Disassembly – Apply localized heat (~250 °C) for removal when needed.

What is loctite 641 used for?

  • Bearings that need to be replaced periodically

  • Bushings or sleeves that require controlled retention

  • Shaft-to-hub assemblies subject to vibration

  • Components where later disassembly or adjustment is planned

Technical Data

PropertyTypical Value
TechnologyAnaerobic
Chemical TypeDimethacrylate ester
Color / AppearanceYellow liquid
Viscosity~600 mPa·s (cP)
Fixture Time (Steel)~20 minutes
Full Cure24 hours
Shear Strength (Steel)~12 N/mm² (≈ 1,700 psi)
Gap Fill CapabilityUp to 0.15 mm
Temperature Range–55 °C to +150 °C
Cure MechanismAnaerobic (air-excluded)
DisassemblyHeat to ~250 °C and disassemble while hot

Note: Performance may vary depending on materials, surface treatment, and ambient conditions. Always consult the Technical Data Sheet (TDS) for full details.

How to Use LOCTITE 641?

1. Surface Preparation
Clean all bonding surfaces with a suitable solvent (e.g., LOCTITE SF 7063) to remove oils, dirt, and residues.

2. Activator (if required)
For passive metals such as stainless steel or plated surfaces, apply LOCTITE SF 7471 or 7649 to speed curing.

3. Adhesive Application

  • Slip fit: Apply to leading edge of the shaft and inside the bore. Rotate during assembly to spread evenly.

  • Press fit: Apply to both surfaces before pressing together.

  • Shrink fit: Apply to shaft; heat housing before assembly.

4. Loctite 641 Curing Time
Allow fixture time of approximately 20 minutes at room temperature. Full cure typically achieved within 24 hours.

5. Disassembly & Rework
To remove, heat bonded parts to around 250 °C and disassemble while hot. Clean off cured adhesive before re-bonding.

FAQs

Q1: Can LOCTITE 641 be removed?
Yes. Its medium-strength formula allows for disassembly using heat and hand tools.

Q2: What materials can it be used on?
It’s compatible with most metals, including steel, aluminum, and plated components.

Q3: How thick can the bond gap be?
For best results, keep the gap ≤ 0.15 mm.

Q4: How can I speed up curing?
Use LOCTITE SF 7471 or 7649 activators on passive metals or in cold conditions.

Q5: What is the temperature limit?
LOCTITE 641 performs reliably from –55 °C to +150 °C.

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