Gasketing applications, anaerobic

In the Automotive industry there is a trend towards complete automation of production lines. In the application of adhesives/sealants for gasketing, the principles of dispensing have normally been to use a pressure-time system, or alternatively a cartridge system with a robotic head. However, a faster system is to screen print an anaerobic on to the surface of a component. 

Appropriate forms of anaerobic composition make very successful gasket replacements - particularly because they are virtually incompressible. Furthermore, the same material may be used to seal several different assemblies unlike the conventional gasketting techniques which are very application specific. 

Joint sealing and retention of co-axial components - often both in the same application - are prime examples. Components can be threaded (screws or pipes), or splined or smooth (eg bearings). Special versions of these adhesives (often not truly anaerobic - in that primers may have to be used) give much higher levels of effective adhesion than the normal materials and so may be used in lap joints. Other versions are formulated as gasketting media. 

Other important applications for anaerobics include the sealing of threaded pipe joints, gasketing, structural adhesives and the bonding of slip fitted cylindrical parts (often called retaining compounds). 

Two major application areas in whch anaerobic sealants have had a profound impact are porous metal impregnation and liquid gasketing. Although the physical properties of the products directed at these areas are extremely dissimilar in the uncured state, the cured materials share common features which render them uniquely suitable as sealants. Both types of product cure to form materials which resist attack by most industrial fluids, counterbalance the effects of surface imperfections, and do not shrink or crack during cure. 

There are altogether at least thirteen different ways in which anaerobic adhesives, sealants and gasketing compounds may be used. The more important applications are discussed below. 

The great benefit of anaerobic compounds, when they are used as gasketing media, is that they allow metal/metal contact between the surfaces being sealed, which means that dimensional stability is immediately obtained and retained. This is particularly important in the application illustrated in Fig. 7.28 where correct alignment is clearly important. 

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