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Powder
coating is a relatively new metal coating technique and was first
introduced in the early 1970's. In this process, powdered resins
along with coloured pigments are applied to metal products using
an Electro-static charge. The product is then "baked" in a high
temperature oven causing the powder to melt, flow, and then cure,
forming a molecular fusion bond. The result is a surface - to- coating
bonding unlike any other.
Over recent years the application of thermosetting powder coatings
on Aluminium has increased dramatically. The wide variety of powder
types now available allow the engineer or architect to specify powder
coating with confidence.
As with solvent based paints thermosetting powders can be formulated
to produce high and low gloss decorative coatings , Metallics as
well as textured & hammered finishes. The standard colour range
gives customers ample choice and if need be, special colour matches
and finishes can be made.
The
Process.
Aluminium components are cleaned and to improve adhesion they can
be primed. It is very important that during the priming stage the
component is kept clean, for this reason Anodising although expensive
is an ideal pre-treatment for painting .
Zinc chromate can also used, but over the last few years a number
of problems have arisen with this form of pre-treatment.
The components are then suspended on a jig or wire and passed through
the spray booth where the powder is applied by Spray Guns . Powder
spray guns can be adjusted for powder and air volume, after spraying
the paint is cured in an oven. Time and temperature vary in accordance
with paint types but 200°C for 20minutes is an average.
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