Automated Powder Coating
Pretreatment (General)
Pretreatment is the most
important step in the powder coating process. It is this process that
ensures adhesion of the coating to the substrate and also provides
maximum long term performance of the final finish. The surface finish can
be visually examined to ensure a quality finish, however what’s underneath
the surface only your powder coater knows.
Mechanical metal pretreatment
is any process where the surface is prepared mechanically such as,
sanding, grinding, media tumbling, sandblasting, shot or glass bead
blasting. This process provides good bonding of the coating to the
substrate due to the surface profile left by the process. The big
disadvantage of using only this process
is that it does not provide any corrosion protection.
Tortoise Pretreatment
TORTOISE
POWDER COATING uses state of the art power washing system. It is a five
step, four stage IRON POSPHATE system. The initial stage contains a heated
chemical that serves a dual function, corrosion resistance and coating
adhesion. The phosphate coating is a porous transition layer between the coating
and the substrate and can absorb the
coating material. Upon curing, the coating solidifies, locking into the phosphate
pores. This action provides the excellent adhesion properties of
powdercoating. The Iron
Phosphate also helps prevent flash rust during the cleaning cycle and
prevents rust creepage in the event the coating is ever chipped during
use. In
order to ensure the integrity of the IRON POSPHATE solution, a daily
titration of the solution is examined. The final D.I. water stage
with low solid water improves the final pretreatment quality by
eliminating any mineral deposits on the parts.
Tortoise also has a state of
the art sandblasting facility to provide mechanical pretreatment where
required. After pretreatment, the product is dried in a dry-off oven
at approximately 400 degrees F to ensure all moisture is evaporated and
the part is ready for coating.
Line Coating
The parts are coated is a self contained powder booth, with the latest
state of the art electronic powder guns. The guns provide the charge
for the powder particles which attach themselves to the grounded parts.
Parts are coated from opposing sides by a minimum of two guns to ensure
accurate dispersal of powder on complex three dimensional parts.
Line Curing
A 30 x 30 foot convection oven is used to cure the parts.
Temperature and time vary depending on the powder chemistry, part material
and part density. The powder goes through a gell and hardening stage
that ensures a uniform, drip free surface.
Final
After the
parts leave the oven, they are air cooled and removed from the conveyor.
The parts receive a final quality inspection and are immediately packed
for shipment.
