LOCTITE® 638™ is designed for the bonding of cylindrical fitting parts, particularly where bond gaps can approach 0.25 mm and where maximum strength at room temperature is required. The product cures when confined in the absence of air between close fitting metal surfaces and prevents loosening and leakage from shock and vibration. Typical applications include locking bushings and sleeves into housings and on shafts. LOCTITE® 638™ provides robust curing performance. It not only works on active metals (e.g. mild steel) but also on passive substrates such as stainless steel and plated surfaces. The product offers high temperature performance and oil tolerance. It tolerates minor surface contaminations from various oils, such as cutting, lubrication, anti-corrosion and protection fluids.
FEATURES AND BENEFITS
- Prevents loosening: It fills all gaps between the cylindrical components and cures into a hard thermoset plastic. This unitizes the assembly and prevents loosening and leakage from shock and vibration.
- Works on all metal substrates.
- Tolerant towards minor surface contaminations.
- High temperature resistance.
- High strength on all metals, including passive substrates (e.g. stainless steel).
APPLICATION
Retaining
PRODUCT CHARACTERISTICS
|
Technology |
Acrylic |
|
Chemical Type |
Urethane methacrylate |
|
Appearance (uncured) |
Green liquidLMS |
|
Fluorescence |
Positive under UV lightLMS |
|
Components |
One component – requires no mixing |
|
Viscosity |
High |
|
Cure |
Anaerobic |
|
Secondary Cure |
Activator |
|
Application |
Retaining |
|
Strength |
High |
TYPICAL PROPERTIES OF UNCURED MATERIAL
|
Specific Gravity @ 25 °C |
1.1 |
|
Flash Point – See SDS |
|
|
Viscosity, Brookfield – RVT, 25 °C, mPa·s (cP)
|
Spindle 3, speed 20 rpm 2,000 to 3,000LMS |
|
Viscosity, Cone & Plate, 25 °C, mPa·s (cP) |
Shear rate 129 s -1 1900 to 3100 |
TYPICAL PROPERTIES OF CURED MATERIAL
|
Physical Properties: |
|
|
Glass Transition Temperature ISO 11359-2, °C |
76 |
|
Coefficient of Thermal Expansion, ISO 11359-2, K ^-1 Below Tg Above Tg |
96×10^-06 192×10^-06 |
|
Adhesive Properties |
|
|
After 15 minutes @ 22 °C Compressive Shear Strength, ISO 10123 Steel pins and collars |
N/mm² ≥13.5LMS (psi) (1,960) |
|
After 24 hours @ 22 °C Compressive Shear Strength, ISO 10123 Steel pins and collars |
N/mm² ≥25LMS (psi) (3,625) |
|
After 7 days @ 22 °C |
|
