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are 5 key stages in the manufacture of powder coatings. |
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Formulation:
The
formulation of powder coatings involves the use of 4 basic raw material types:
resins, pigments, curing agents and additives. Resins provide strength, durability
and adhesion; pigments add colour; curing agents cause the resins bond to the
substrate and harden; additives are used to enhance the coatings properties, such
as improving flow-out or application properties.
All raw materials used in Synthatec products have been carefully selected
and thoroughly tested to ensure that they meet the rigorous demands of the architectural
market.
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Artificial
weathering testing at Valspars in-house facility.
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Cooled extrudate
entering the 'kibbler'.
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Premix:
Once
a product has been formulated and is ready for manufacture, raw materials are
carefully weighed and measured. These raw materials are then blended together,
either by high-speed mixing or tumbling, to ensure a consistent dispersion of
raw materials throughout the mixture.
Extrusion:
The
mixed raw materials are then fed into an extruder. The extruder applies pressure
and heat to melt the resins and thoroughly incorporate the pigments, curing agents
and other ingredients into a homogenous substance.
The extrudate is cooled and chipped, reading for quality checking and micronising.
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Micronising:
Once
the extrudate has been cooled, chipped and quality checked it is ready for micronising.
Micronising grinds the chip into a fine powder. This powder is sieved and classified
to ensure an even particle size distribution. Particles which are under 10 micrometres
or above 120 micrometres in size can cause application problems and are removed
by the sieving and classification process.
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Valpars
automated micronising and box filling system.
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Spraying test
panels in the QC department
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Quality
Control:
Quality control checks are made at both the extrusion and micronising stages
of the manufacturing process.
Extrusion
stage: Chip from the extruder is ground and the resulting powder applied to
test panels. The following tests must be passed before production continues:
- Film Thickness
- the thickness of the cured coatings is checked to ensure that it meets the appropriate
specification for further testing.
- Colour
- colour is checked both visually and by computer against the standard and the
last batch to ensure that there is no colour variation.
- Gloss -
panels are tested to ensure that the gloss level meets the specification for the
product.
- Mechanical
Impact - Test panels are subjected to a 20"/lb mechanical impact with no
cracking or loss of adhesion.
- Visual
surface inspection - panels are inspected visually for contamination and inclusions
in the coating.
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Micronising
stage:
Finished powder from the microniser is applied to test panels. The following tests
must be passed before product is placed into stock:
- Film Thickness
- the thickness of the cured coatings is checked to ensure that it meets the appropriate
specification for further testing.
- Colour
- colour is checked both visually and by computer against the standard and the
last batch to ensure that there is no colour variation.
- Gloss -
panels are tested to ensure that the gloss level meets the specification for the
product.
- Mechanical
Impact - Test panels are subjected to a 20"/lb mechanical impact with no
cracking or loss of adhesion.
- Erichsen
Cupping - A ball bearing is mechanically forced into the surface of the panel,
creating a 'cup' on the surface, testing the flexibility and adhesion of the coating
under sustained pressure. Products must pass this test with a 7mm cupping and
no cracking of the coating.
- Particle
size - particle size is important to ensure consistent, high quality application
of the product. A computerised laser scanning particle size measurer is used to
ensure that less than 10% of particles < 10 microns, less than 3% > 120
microns, and the majority are between 34 and 42 microns.
- Visual
surface inspection - panels are inspected visually for contamination and inclusions
in the coating.
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Mechanical
impact testing
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