Applications

LOCTITE® 638™ – Retaining Compound – Bonding of Cylindrical Fitting Parts

Item Name: LOCTITE® 638™
Manufacturer: Henkel
Technologies: Acrylic, Urethane Methacrylate
Color: Green
Cure Type: Anaerobic, Secondary Cure with Activator
Package Size: Contact to Techniq VN for details.
Shelf Life: Contact to Techniq VN for details.

1. Product Overview

  • Technology: Acrylic
  • Chemical Type: Urethane methacrylate
  • Appearance: Green liquid
  • Cure Type: Anaerobic (secondary cure with activator)
  • Application: High-strength retaining compound for cylindrical fitting parts
  • Key Features:
    • Works with gaps up to 0.25 mm
    • Resistant to shock, vibration, and oil contamination
    • High-temperature stability
    • Suitable for active and passive metals

2. Applications

  • Retaining bushings, sleeves, and bearings in housings and shafts
  • High-strength bonding of cylindrical parts

3. Typical Properties

Unmixed Properties
Property Value
Specific Gravity @ 23°C 1.1
Viscosity (Brookfield RVT, 25°C, 20 rpm) 2,500 mPa·s (cP)
Fluorescence Yes (under UV light)
Mixed / Cured Properties (after 24h @ 23°C)
Property Value
Glass Transition Temperature (Tg) 76°C
Coefficient of Thermal Expansion (below Tg) 96 × 10⁻⁶ K⁻¹
Coefficient of Thermal Expansion (above Tg) 192 × 10⁻⁶ K⁻¹
Adhesive Strength (ISO 10123)
Substrate Strength (N/mm² / psi)
Steel (cured 72h @ 23°C) 29 / 4,200
Stainless Steel (cured 72h @ 23°C) 28 / 4,000
Aluminum (cured 72h @ 23°C) 17 / 2,710
Torque Strength (ISO 10964)
Condition Value (N·m / lb·in)
Breakaway Torque (M10 bolts) 57 / 510
Prevail Torque (M10 bolts) 22 / 200
Environmental Resistance (Steel Pins & Collars, 5000h exposure)
Chemical Temperature (°C) Strength Retention (%)
Motor oil (5W40) 125°C 165%
Brake fluid 23°C 115%
Water/glycol 50/50 87°C 145%
Ethanol 23°C 100%
Acetone 23°C 105%
Operating Temperature Range
Condition Temperature (°C)
Minimum -75°C
Maximum 250°C

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