Canadian Finishing & Coatings Manufacturing September/October Issue - 18

INDUSTRIAL FINISHING: POWDER COATING
FLYING
COLOURS
Advancements in automation make quick colour change a breeze
and coating complex geometries more dynamic
F
or the powder coating market, colour change has been
and will continue to be a key focus of the business.
The need for colour variety has infiltrated a number
of industries in recent years-consumers demand a
spectrum of shades for vehicles, appliances, outdoor equipment,
and even complex rugged equipment-and colour is the way
manufacturers differentiate their products. With such complex
demands, powder
coating equipment manufacturers have
answered with not only more flexible and automated colour
change technology, but also advancements in spray application
equipment.
Traditional technology such as cartridge/modular booths,
which require a collector per colour, works well and delivers
powder reclaim capabilities at a low cost, but it does have some
inefficiencies and requires highly experienced operators. " The
cartridge booth technology separated everything from the
airstream, whether it was good powder or powder fines, which are
small particulates that won't charge, are difficult to fluidise, and
tough to pump. And in a closed loop system those powder fines
build up over time and you have to get rid of them by dumping the
hopper and start with new virgin powder, " says JR Rogers, North
American engineered systems sales manager for Wagner.
Dave Szymczak, powder coating specialist at PPG Industries,
agrees. " With colour modules the particle size on the reclaimed
powder will be lower, and you need to mix the reclaim with the
virgin material at a certain ratio. This is all related to first pass
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efficiency (FPTE). If you're coating something simple like a
flat tabletop you might get a 50 to 60 per cent FPTE, but if it's
something more complex like a bike frame that FPTE will be
much lower. With standard modules it's very important to control
that virgin/reclaim ratio because that ratio is going to be a higher
percentage of reclaim versus virgin. "
" And if you're not using that reclaimed material as it's produced,
there is more potential for contamination, and film build control
is going to suffer or vary in the standard modules because the
particle size distribution is going to change throughout the day,
and the operator will be constantly adjusting settings or they're
running scrap parts because the film build is too low. The powder
booths are essentially a vacuum cleaner-whatever is in that
environment can be airborne contaminants that can make it into
the reclaim system, " says Szymczak. " But now there are cyclone
booths that run cleaner and automate the transfer of the reclaim
through the cyclone and back into the feed hopper. Some of those
contaminants might be in there, but they're not in there long. "
The industry's focus has certainly shifted to cyclone booth
technology in recent years. These highly automated booths use
cyclone technology to separate the powder from the air, classify
the fines and only pull good, reclaimed powder back into the
hopper or feed system.
" By classifying the powder, we can maintain consistent and
uniform coverage, " says Rogers.
This technology also offers a drastic reduction in colour change
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Canadian Finishing & Coatings Manufacturing September/October Issue

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