Loctite retaining adhesives are a proven method of securing bearings, bushes and cylindrical parts into housings or onto shafts, but thanks to continuous development their performance is now better than ever. Two of the company’s most popular products in this range, Loctite 638 and 648, have been re-launched with improved temperature resistance and greater oil tolerance. They also have the ability to cure well on passive metal surfaces such as aluminium or stainless steel.
When compared with conventional assembly methods, these Loctite retaining adhesives offer many advantages. They provide 100 per cent contact over the entire bond surface. This allows stress to be distributed evenly over the joint which, in turn, enables higher loads to be carried. The bond also prevents moisture from entering the joint and eliminates fretting that commonly leads to corrosion, accelerated wear and premature failure.
Loctite retaining adhesives are also beneficial when used in combination with shrink or press fit assemblies. Higher load transmission and performance can be achieved with existing designs and geometries. Alternatively, they allow a similar level of performance to be maintained by lower interference or lighter constructions.
The original Loctite 638 was introduced as the best class for resistance to dynamic, axial and radial loads. It was, however, only suitable for operating temperatures between -55degC to +150degC. The latest generation version boosts the maximum temperature to 180degC, and tests confirm that it also has superior heat ageing properties than its forerunner.
For applications requiring increased temperature resistance, Loctite 648 has always been recommended but its performance has also been improved. It now offers significantly higher temperature resistance at 180degC and can even be used effectively at service temperatures of 200degC.
Both new products will also cure effectively even if the mating surfaces are not perfectly cleaned. They will tolerate light contamination of oils, cutting and cleaning fluids commonly found in the factory environment.
Importantly, these attributes have been achieved without compromising any of the key properties such as cure speed and bond strength. In fact, both products show faster strength development on both mild steel and aluminium. Chemical resistance is another area where the new Loctite products demonstrate greater tolerance.
Available now, both the upgraded Loctite 638 and 648 retaining adhesives carry WRAS approval for the UK water industry and are currently undergoing certification from DVGW and NSF. For further information please visit www.loctite.co.uk.