LOCTITE® 638 High Strength Retaining Compound
Features and Benefits
- Ideal for shafts, gears, pulleys and similar cylindrical parts
- High strength on all metals, including passive substrates (e.g. stainless steel)
- High temperature resistance
- Fluorescent under UV for quality control
- Hydrogen gas approval for sealing threaded metal fittings according to KIWA GASTEC QA AR 214
Documents and Downloads
Looking for a TDS or SDS in another language?
Technical Information
Agency approvals / certificates / specifications | DVGW (EN 751-1): NG-5146AR0619, NSF P1 Reg. No 123010, WRAS (BS 6920): 0511518 |
Application method | Dispense system, Manual |
Applications | For close fitting cylindrical parts, For slip fitted parts, Retaining |
Color | Green |
Cure type | Anaerobic cure |
Fixture time | 4.0 min. |
Gap fill | 0.15 - 0.25 mm |
Key characteristics | Fluorescent, Oil tolerant, Strength: high strength, Temperature resistant, Viscosity: high viscosity |
Operating temperature | -55.0 - 180.0 °C (-65.0 - 355.0 °F ) |
Physical form | Liquid |
Recommended for use with | Metal: steel |
Shear strength, Steel | 31.0 N/mm² (4500.0 psi ) |
Viscosity | 2500.0 mPa·s (cP) |
How to
Step by Step Guide
1. Preparation - Cleaning
Use LOCTITE® SF 7200 or LOCTITE® SF 790 to remove any old adhesive from parts. Use LOCTITE® SF 7063, SF 7064 or SF 7070 to degrease and clean surfaces prior to applying adhesive. For gaps larger than 0.5mm or worn out shafts, bearing seats or keyways, use LOCTITE® metal-filled compounds to rebuild the surfaces.
2. Preparation - Activation
If cure speed is too slow due to passive metals or low temperature (below 5°C), use activator LOCTITE® 7240 or LOCTITE® 7649 (see cure speed vs activator graph in the TDS). Allow to dry.
3a. Application - For Slip-Fitted Assemblies
Apply adhesive around the leading edge of the male component and the inside of the female component and use a rotating motion during assembly to ensure good coverage.
3b. Application - For Press-Fitted Assemblies
Apply adhesive thoroughly to both bond surfaces and assemble at high press on rates.
3c. Application - For Shrink-Fitted Assemblies
Apply the adhesive onto the shaft; heat the collar to create enough clearance for free assembly.
4. Disassembly
Apply localized heat to approximately 500°F/260°C; disassemble while hot. For corroded or seized parts, use LOCTITE® 8040 Freeze and Release.
Equipment
For manual assembly of adhesive the use of LOCTITE® Pro Pump or LOCTITE® Peristaltic Hand Pump is recommended to ensure a consistent application volume. For semi-automatic or fully-automated dispensing options contact our technical service team for advice.