Canadian Finishing & Coatings Manufacturing - May/June '24 - 15

INDUSTRIAL FINISHING: LIQUID GUN TECHNOLOGY
beta testing the new guns and customers are saying that
they've never been able to spray a product so well and are
able to reduce the flow rates. With this new technology,
we're able to control the atomisation process, get a more
uniform particle size throughout the spray pattern and
achieve a better spray pattern density. Because of that
there's an inherent increase in transfer efficiency of about
three to five per cent. "
" And we don't have to take as many passes across a
surface to get good hiding, " says Owed. " What we saw with
the DV1 and what we're seeing with the new gun is that not
only do we have improved TE due to the new technology,
but we get a better application and, in some cases, we're
seeing a 20 per cent reduction in the amount of material
that needs to be sprayed to get hiding or coverage. "
The new generation gun is air atomised, low volume,
medium pressure (LVMP)-under 300psi-and can be
fed from a pressure pot or gravity fed. And in the future,
Carlisle Fluid will be taking this gun to an electrostatic
platform.
Rotary atomisers provide the best atomisation and the
most uniform droplet size of all the technologies. With
proper air shaping controls, a pattern can be adjusted in
process to help with the penetration of complex parts,
according to Tellitocci. These applicators will also provide
the best transfer efficiency and the highest finish quality.
Sames recently introduced its range-eight series of
rotary atomizers. Following the launch of its Nanobell
801-the company's first non-electrostatic bell atomiser
designed for general industry-the Nanobell 803 is its
latest electrostatic bell applicator with a significant TE
compared to the 801.
" The rotary atomisers give you a higher transfer
efficiency not only because of electrostatics, but because
you have a lower particle velocity. It uses centrifugal force
and mechanical shearing in creating the droplets, " says
Owed. " With air spray, you have a fluid column, and you
use air to create the droplets. But with that you put a lot of
forward energy into it and that's what creates overspray. "
Air spray technology creates a fan or elliptical pattern,
whereas rotary guns produce a round pattern. And when
you put a rotary atomiser on a robot, it doesn't have to
articulate as much to coat a part, and you'll see about a 10
to 15 per cent TE because the cup is constantly spinning,
which also allows you to trigger directly on the part.
When you add electrostatics to a liquid spray technology,
transfer efficiencies are improved even more, but it is more
of an investment.
Tellitocci says, " There are fire protection requirements
with electrostatics. High-speed deluge and spark detectors
are required when electrostatics are used. This greatly
increases the cost of a project if these systems are not
previously in use. Additionally, good grounding of the parts
to be sprayed is mandatory. "
Owed says that when you add electrostatics to air spray
technology you can usually cut material usage in half. And
when you transition from air spray to rotary technology
you can reduce material usage from a half to a third.
" A good rule of thumb is that Airless and Air mix guns
can provide a TE of up to 60 to 70 per cent, with air spray
a TE of 30 to 50 per cent is not unusual. Rotary atomisers can
provide up to 80 to 90 per cent TE. Keep in mind that these
numbers are under ideal conditions, " says Tellitocci. " Once
electrostatics are added to different technologies an increase of
20 to 30 per cent in TE can be expected. "
For shops that initially invested in entry level technology
for a finishing process, investigating these advancements
in technology and working with your equipment suppliers
to improve coating processes will not only advance overall
efficiencies, but also significantly cut material and energy
costs.
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800.573.5554 USA * 800.450.0655 CAN
marketing.us@sames.com * sames.com
May/June 2024
15
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Canadian Finishing & Coatings Manufacturing - May/June '24

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