Retaining adhesives go from strength to strength

16 June 2014

Loctite retaining adhesives are a proven method of securing bearings, bushes and cylindrical parts into housings or on to shafts but following 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 to conventional assembly methods these Loctite retaining adhesives provide 100% 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.

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 -55°C to +150°C. This latest generation version boosts the maximum temperature to 180°C and tests confirm that it also has superior heat ageing properties than its forerunner. It now offers higher temperature resistance and can be used effectively at service temperatures of 200°C.

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.
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.

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