As the name suggests, they work in seconds and are ideal for bonding close fitting parts made from a variety of materials. They offer advantages over other forms of joining, such as plastic welding, two-part or heat-cured adhesives and mechanical fasteners. The benefits include faster assembly times, better appearance, less outlay for capital equipment and these adhesives can also be used to repair metal, plastic, rubber or ceramic components which might otherwise be scrapped.
Instant adhesives are available for the following applications:
(a) General purpose adhesive for plated metals, composite materials, wood, cork, foam, leather, paper - all surfaces which were once considered 'difficult' - can now be bonded quickly and permanently.
(b) A special rubber and plastics adhesive ensures fast-
fixturing of elastomers and rubbers, especially EPDM rubber. Bonds polyethylene, polypropylene and polyolefin plastics.
(c) A gel-type adhesive can be used for fabrics, paper, phenolic, PVC, neoprene and nitrile rubber and bond them in 5 seconds; ceramic, leather, and balsa wood in 10; mild steel in 20; ABS and pine in 30. The gel form prevents absorption by porous materials and enables it to be applied to overhead and vertical surfaces without running or dripping.
(d) A low odour, low bloom adhesive has been developed where application vapours have been removed with no possibility of contamination. A cosmetically perfect appearance can be obtained. The absence of fumes during application means that it can be safely used close to delicate electrical and electronic assemblies, alongside optics and in unventilated spaces.
(e) A black rubber toughened instant adhesive gives superior resistance to peel and shock loads. Tests show bonds on grit blasted mild steel can expect a peel strength of 4 N/mm at full cure.
All adhesives can be applied direct from bottle, tube or standard automatic application equipment on to surfaces which require very little pretreatment.
In most cases, just one drop of instant adhesive is enough to form an extremely strong, virtually
unbreakable bond. There is no adhesive mixing, and cure takes place in seconds to give a joint with maximum surface to surface contact.
Four typical production applications are shown in Fig. 29.12.
The illustration in Fig. 29.12(c) shows an operator using a semi automatic dispenser. The bonding product is contained in a bottle pack and dispensing regulated by an electronic timer controlled pinch valve mounted on the unit. The dispense function can be initiated in a variety of ways, including a footswitch. The point of application is controlled by hand.
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