Anaerobic adhesives performance problems

The problems associated with threaded fasteners loosening in service are well known and have been investigated in detail. Anaerobic adhesives have been shown over many years to be particularly effective threadlocking materials. This stems from their ability to completely fill the space between threaded components, so preventing movement — whether axial, transverse or rotational. A comparison " of mechanical locking methods and the use of anaerobic adhesives has confirmed the superior performance of adhesively locked joints under shock and vibration loading. 

The retention of studs by conventional methods requires accurate machining, blind holes, and presents potential assembly problems. The use of anaerobic adhesives with free-fitting studs eliminates these difficulties and, as a bonus, gives a better dynamic performance and easier maintenance. 

Anaerobic adhesives have been available for many years in a micro-encapsulated form. Fasteners are coated by deposition from a slurry. When dry the fasteners can be stored until required. Whilst this approach has obvious benefits for on-part inspection these products have had limited success due to shelf life problems and inconsistent locking performance. ... 

Finally, care must be taken, either in the choice of adhesive or in the assembly technique, to ensure that the adhesive is not wiped from the surface as the parts are placed together. This is likely where, for example, one part is slid into position over another the sliding action tends to wipe the adhesive from the joint area, forming pockets and reducing overall performance. In this context, co-axial assemblies must of course be slid together because of the very nature of the joint. This can cause severe problems for some adhesives but presents no difficulties for the anaerobic varieties, which are formulated specifically to cope with this type of work. 

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