Sticky solutions
Adhesives and sealants virtually touch every
part of our lives. Aditi Gangavkar explores the
basics of these wonder fasteners
Your imagination may fail if you start
tallying the number of day-to-day
applications that use adhesives or
sealants. And once you realise the
potential of these fasteners, you are most likely to get
boggled by the number of options available and of
course, by the tricky task of choosing the right
adhesives for a particular job. Nevertheless, identifying
the right adhesive or sealant for a particular industry
application can be a smooth ride, once its basics are
well understood. Manufacturers while selecting
adhesives should comprehend the fact that every
adhesive or sealant has certain strengths. As such,
design engineers need to carefully examine material
characteristics such as viscosity, adhesion and bond
strength. In addition, they must consider the
manufacturing process, since high-speed, automated
lines have different requirements from low-volume,
manual operations. Thus, adhesive properties such as
assembly rate and cure speed also demand attention.
Frank Schneider, Export Manager, Hernon
Manufacturing give valuable insights on the types of
adhesives available for different industry purposes.
"Adhesives and sealants offer smooth controls,
outstanding fatigue resistance, good bonding strength
and are faster and less expensive. However, the need
for surface preparation could be regarded as one
disadvantage of adhesives," he says.
Moving on to the specifics, Mr Schneider explains
that anaerobic adhesives cure when in contact with
metal and in the absence of air. Often known as
"locking compounds", they are used to secure, seal
and retain turned, threaded, or similarly close fitting
parts. Next in line are the cyanoacrylate (CA)
adhesives, which cure through reaction with moisture
held on the surface to be bonded. Requiring close
fitting joints, they usually solidify in seconds and are
well suited for small plastic parts and rubber. Then
comes the epoxy adhesives and these consist of an
epoxy resin plus a hardener. These materials have
good strength, do not produce volatiles during curing,
and have low shrinkage. Epoxy adhesives are available
in one part, two part and film form and produce
extremely strong durable bonds with most materials.
Yet another kind of adhesive are the UV curing
adhesives, which are widely used in optical lamination
of precision optical lenses, safety windows,
holographic displays, and flat panel displays. In most
of these applications they are being used in relatively
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