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LOCTITE 638 High Strength Retaining Compound

Features and Benefits

TDS Download
LOCTITE 638 is a high strength, fast curing, general purpose retaining compound.
LOCTITE® 638 is designed for the bonding of cylindrical fitting parts, particularly with narrow bond gaps approaching 0.25 mm. The product cures when confined in the absence of air between close-fitting metal surfaces and prevents loosening and leakage due to shock and vibration. It not only works on active metals but also on passive substrates, exhibiting robust cure performance. The product offers high-temperature performance and good oil tolerance, and tolerates minor surface contaminants.
  • Tolerates minor contaminants, including industrial oils
  • High strength on all metals, including passive substrates (e.g. stainless steel)
  • High temperature resistance
  • Ideal for shafts, gears, pulleys and similar cylindrical parts
  • DVGW Approval (EN 751-1): NG-5146AR0619
  • P1 NSF Reg. No.: 123010
  • WRAS Approval (BS 6920): 0511518
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Documents and Downloads

Safety Data Sheets and RoHs
LOCTITE 638, 250ml 1835925 en-US
IDH: 1835925
EAN: 079340006409

Size Case: 250 ml Bottle

Quantity: 10.0/case

LOCTITE 638, 50ml 1835936 en-US
IDH: 1835936
EAN: 079340006393

Size Case: 50 ml Bottle

Quantity: 10.0/case

LOCTITE 638 Retaining Compound 1835937 en-US
IDH: 1835937
EAN: 079340006386

Size Case: 10 ml Bottle

Quantity: 10.0/case

No documents found

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
Shear strength, Steel 31.0 N/mm² (4500.0 psi )
Substrates Metal: Steel
Viscosity 2500.0 mPa·s (cP)

How to

Step by Step Guide

1. Preparation - Cleaning

Use LOCTITE® SF 790™ to remove any old adhesive from parts. Use LOCTITE® 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 (stainless steel, aluminum and plated metals) or low temperature (below 5°C), use LOCTITE® SF 7649™ activator. 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. Assemble parts with a rotating motion to ensure good coverage. Wipe off excess adhesive.

3b. Application - For Press-Fitted Assemblies

Apply 360 degree beads of adhesive to both bond surfaces at the leading edges of insertion or engagement, and assemble at high press-on rates. Wipe off excess adhesive.

3c. Application - For Shrink-Fitted Assemblies

Apply the adhesive onto the male component; heat the female component to cause expansion for free assembly. Assemble components and allow temperatures to equilibrate. Wipe of excess adhesive.

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.


For manual assembly of adhesive the use of LOCTITE® Pro Pump or LOCTITE® Peristaltic Hand Pump is recommended to ensure a conistent application volume. For semi-automatic or fully-automated dispensing options contact our technical service team for advice.

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LOCTITE 638 is a high strength, fast curing, general purpose retaining compound.

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