The electrostatic application of powder coating to a part
begins with fluidization. Fluidization is a process where
powder being sprayed mixes with compressed air,
enabling it to be pumped from a container and supplied to
the spray guns. The powder flow is regulated by controlling
the air supplied to the pump. The powder supplied to
the spray gun is charged using either a corona or tribocharging
gun. Charged powder moves to the grounded
workpiece with the help of air supplied to the guns and
the airflow in the booth.
When the powder particles come close to the part, an
electrostatic attraction between the charged powder particles
and the grounded part adheres powder to the part.
The coated part then passes through an oven and is
cured. The oversprayed powder is contained within an
enclosure and drawn into the primary filter cartridges by a
centrifugal fan. Circulating air, now free of powder, is discharged
through high-efficiency final filters into the plant
as clean air. The primary filter cartridges are periodically
reverse-pulsed to remove oversprayed powder. The powder
is then sieved and supplied back to the guns to provide
extremely efficient material for use again. A simple diagram
showing how this process works is shown in Figure