Loctite 638 - Retaining Compound - 250 ml

LOCTITE 638 – High-Strength Retaining Compound

LOCTITE 638 is a high-strength, green anaerobic retaining compound designed for securing cylindrical, close-fitting metal components. It is particularly suitable for shafts, bearings, bushes, gears, rotors, pulleys and other cylindrical assemblies where a strong, reliable bond is required.

LOCTITE 638 cures when confined between close-fitting metal surfaces in the absence of air. It fills the clearance between mating cylindrical surfaces, creating a strong connection that helps prevent movement, fretting and corrosion.

Key Features

• High-strength retaining compound

• Green color for easy identification

• Designed for cylindrical, close-fitting metal components

• Prevents rotation and axial movement

• Helps secure bearings, bushes, gears and shafts

• Fills small gaps between mating surfaces

• Provides excellent resistance to vibration and shock

• Helps prevent fretting and corrosion

• Suitable for demanding industrial assembly and maintenance applications

Typical Applications

LOCTITE 638 can be used for retaining:

• Bearings on shafts

• Bushes in housings

• Gears and sprockets

• Rotors

• Pulleys

• Sleeves

• Shafts and hubs

• Keyless shaft connections

• Cylindrical metal assemblies

It is especially useful where conventional mechanical methods such as keys, splines or interference fits may not provide sufficient retention or where additional security is required.

How LOCTITE 638 Works

When LOCTITE 638 is applied between closely fitting cylindrical metal surfaces, the adhesive fills the microscopic clearance between the components. Once the assembly is made, the absence of air between the surfaces allows the product to cure and form a strong polymerized bond.

This creates a more uniform load distribution across the mating surfaces and helps prevent relative movement between the shaft and hub or between a bearing and its housing.

Application Procedure

1. Clean and degrease the shaft and mating bore thoroughly.

2. Apply LOCTITE 638 evenly to the bonding surfaces.

3. Assemble the components with the required alignment.

4. Remove excess adhesive from exposed areas.

5. Allow adequate curing time before applying full operating loads.

For maximum performance, surfaces should be clean, dry and free from oil, grease and other contaminants. On inactive metal surfaces or where faster curing is required, a suitable LOCTITE activator may be considered.

Advantages of LOCTITE 638

LOCTITE 638 can provide several advantages over conventional mechanical retention methods:

• Reduces component movement

• Improves load distribution

• Helps prevent fretting

• Provides additional sealing between mating surfaces

• Can compensate for small surface imperfections

• Helps protect against corrosion in the bonded area

• Suitable for high-performance industrial assemblies

LOCTITE 638 vs Threadlocker

Unlike products such as LOCTITE 242 or LOCTITE 222, which are designed for threaded fasteners, LOCTITE 638 is a retaining compound designed for cylindrical assemblies.

LOCTITE 638 is commonly selected when the requirement is to prevent rotation or axial movement between a shaft and a hub, bearing, bush or similar cylindrical component.