LOCTITE® 638 is a high-strength retaining compound designed for bonding close-fitting cylindrical components with gaps from 0.15 mm to 0.25 mm (0.006" to 0.01"). Its high-viscosity, single-part formulation performs across active and passive metals, including stainless steel, while tolerating minor surface contamination from industrial oils. Typical applications include shafts, gears, pulleys, and comparable cylindrical assemblies where durable retention and resistance to movement are required.
The compound offers a fixture time of approximately four minutes, operating capability from -55°C to 180°C (-65°F to 355°F), and fluorescence under UV light to support inspection and quality-control procedures. LOCTITE® 638 may also be used for high-strength threadlocking and thread sealing. In select countries, it is certified to KIWA GASTEC QA AR 214 requirements for metal threaded fittings used with admixtures containing up to 100% hydrogen gas.
