To review the latest developments in application
technology, these advancements have been delineated
into the various components of a powder spray system
including guns, delivery devices (e.g. hoppers, pumps,
hoses, etc.), reclaim systems and gun movers. Color
change technology and equipment specifically designed
for non-traditional substrates is also included. Some
really cool developments have emerged, ranging from
something simple and perhaps obvious, like an LED
light attached to a manual gun body, to sophisticated
electrostatic charging systems.
Gun Design
One innovative advancement focuses on powder
application technology with a unique rotating electrostatic
powder bell applicator. The rotating bell sprayer reportedly
delivers high performance, excellent finishing quality and
easy integration. It also provides high transfer efficiency
rates with easy maintenance. This unique technology will
be showcased at the FABTECH show in November.
Undoubtedly the most fun innovation is the integration
of an LED light atop a manual spray gun. It’s so popular
that it is now a standard feature for some manufacturers.
Manual handguns with LED lights allow an operator to
better see what he is painting. The LED light receives
power from the multiplier residual field around the gun,
requiring no additional power source. The light can be
kept on for an additional 15 seconds after the trigger is
released. This new innovation is said to have reduced
reject rates and increased line speeds.
Some powder applicator equipment suppliers have
focused on the efficiency of a gun’s charging mechanism,
continuing to improve upon technology for high efficiency,
advanced corona charging. The technology lets users get
the full benefit of high voltage (high transfer efficiency)
and low gun current, simultaneously using the latest
modulation technology (same as used in motor speed
controllers, welding equipment, plating lines, and light
dimmers). In addition, electrostatic scientists are finding
ways to optimize duty cycles and frequencies for a wide
range of powder coating conditions.
Another interesting development utilizes light weight
combined with low current operation which minimizes
the generation of excessive heat in the cascade, making it
much more efficient and less likely to breakdown due to
high temperatures. Furthermore, these types of guns are
well suited for use in dry-on-dry powder systems where
back ionization and Faraday cage penetration are problems
because they minimize high excess free ions on corners
that can lead to powder pull back.
Delivery Systems
Dense phase pumping systems debuted about 10 years
ago and continue to evolve. Today’s newer models have easier serviceability, featuring one screw disassembly
and longer pinch valve life. Repeatability in dense phase
pumps without having to adjust for wear of a venturi style
pump throat drives user acceptance of this technology.
The ability to have effective flow rate outputs, with higher
transfer efficiency up to four times that of a traditional
pumping system, make coating large and difficult parts
more time efficient. Low air output at the front of the guns
prevents powder from being blown out of Faraday areas.
Spraying and cleaning performance have improved with
new application pump and electrostatic gun designs. This
technology enhances powder application uniformity and
consistency, boosting transfer efficiency and reducing the
amount of powder that is sprayed. All of this increases
material utilization and makes for easier and faster color
changes.
In addition, there have been developments in advanced
powder feed technology that features full, closed loop,
real time feedback on powder flow to the gun. This
technology allows users to “dial in” a powder flow and
maintain that flow throughout all types of operating
conditions in real time.
Advances in application technology have improved powder
application and consistency, transfer efficiency and has made
color changes easier and faster.
Color change
The issue of quick color change technology is nothing
new to the powder industry. The difficulty of executing
a swift color change in a powder booth has haunted
application engineers for decades. Thankfully, major
powder system designers have continued to bolster this
technology, resulting in the ability to change color in as fast
as 20 seconds (spray to non-reclaim) and five to 10 minutes
in reclaiming systems. The limitation is in the payback
based on volume of powder sprayed, not on the various
equipment available to customers. Additional approaches
center around sophisticated powder management as
a key element of quick color change systems. Powder
management centers and the latest booth designs work in
conjunction to minimize the amount of powder that is in
process, which enables the user to perform a color change
quickly and easily with no risk of contamination.
Reclaim Systems
Innovations in reclaim systems have augmented quicker
color changes. Time to change color is minimized with the
use of automation and the elimination of as much powder
in process as possible. This includes technology that
automatically cleans the application system (pump, hose,
gun), booths that constantly return overspray powder to
the feed system, and feed systems that have small powder
reservoirs to allow for faster, more automated cleanup at
color change.
Gun Movers
Gun movement technology is not standing still. Gun
oscillators and reciprocators are becoming as “smart” as
possible by tying them to vision systems that can identify
the part geometry and adjust on-the-fly based on size, shape
and line speed. The use of robotics continues to grow with
over 200 systems now in use in North America, mainly due
to a significant reduction in price. The cost of installing a
fully functioning robot is approaching that of traditional
gun mover systems. Robots are easily reprogrammed as
customer part configurations change, making them a more
desirable solution than traditional gun mover systems with
limited ability to access tight recessed areas.
Systems for non-traditional substrates
Interestingly, systems for non-traditional substrates
such as MDF (medium density fiberboard) and plastic
substrates are not a focal point for equipment suppliers.
Not surprisingly, most electrostatic equipment that works
for traditional metal substrates can work for application
to more exotic substrates, including MDF, composites and
plastics. The key to acceptable application is preparation of
the surface to be coated. Non-conductive substrates require
a conductive agent or coating to be applied prior to the
powder application. MDF can be preheated to facilitate the attraction and deposition of
electrostatically-charged powder. The
reality is systems required for coating
non-metal substrates are generally the
same from an application and booth
supplier standpoint. The limitation is
in the prep and cure of the substrate,
not in the application and recovery
end. The question one must ask is
how many resources should be spent
on a science project that nets the same
revenue as a traditional metal coating
application. Exotic coating needs to be driven by the material supplier; the
application and equipment suppliers
can coat it if the material can produce
the desired end user result.
The Biggest Unmet Needs
in Powder Application
Technology Today
Depending on who you talk to,
opinions on where powder application
technology needs remain unmet can
vary widely. Some feel that First Pass Transfer Efficiency (FPTE) requires
additional attention as less overspray
means less clean-up, making any
color change easier and faster to
perform. Others believe that measuring
the film build on parts before they
enter the cure oven is a technology
space ripe for advancement. Current
models can tell what is being applied
in a general range, but there is no onthe-fly
adjustment to the application
equipment. Technology that allows
accurate reading of pre-cure parts to
compare to specification for final cure
as well as a feedback loop that then
makes changes to the appropriate
application devices to correct deviations
real time would provide more efficient
powder use and a significant reduction
of reject and/or rework parts.
It’s no surprise that a march toward
achieving Industry 4.0 is evident on
a number of fronts. Improvements
will continue to be made in material
handling, allowing for better control
and management of the powder
while spraying and cleaning. This
includes incorporating automation
controls linking machines together
and enhanced communication and
data sharing for the emerging trends
associated with Industry 4.0.
Integral to Industry 4.0 is the
gathering and using of information
that allows for remote information
collection which avails intervention.
Currently, apps exist to monitor the
equipment, but the ability to make
remote adjustments —e.g. if KV is
low or flow rates are off set points—is
only available on a limited basis. Some
manufacturers recently introduced
this function. Question also remains in
terms of information overload. Asking
for information is easy but doing
something with the output is often not
achieved.
Industry 4.0 improvements continue to be made by linking machines together
through automation controls and improved communication and data sharing.
Not all unmet needs in the industry
are tied to technological advancements.
A somewhat obvious, less technical
challenge is the importance of ground
for successful powder coating. Often
overlooked if not completely ignored
in the field, we need to find a way to
quantify the cost of bad ground. Until that is done, investments required
for improving ground path will not
happen.
Another ongoing issue in the
industry is education. We could have
the best technology in the world, but it
is useless without a skilled workforce
that understands it and knows how
to operate it at an appropriate level.
Simply stated, we need to find a better
way to communicate and deliver
training. There seems to be a lot of
turnover when it comes to painters
and too often training of new painters
consists of handing them a gun and
telling them to spray the part.
Opportunities for Growth
Interestingly, one of the most
prevalent growth areas in the powder
coating industry continues to be
the traditional conversions from old
paint technology to powder. Liquid to
powder conversions are still happening
and each of these conversions is a great opportunity for growth within
the powder market. Hands down,
powder coatings are the best solution
for companies looking for “green”
coating solutions. Any company
that is considering a conversion
to waterborne coatings as a finish
solution should strongly consider
converting to powder coatings.
The economic, environmental, and
performance advantages make powder
coatings an excellent choice.
Service, training and technology
may be the next growth areas in the
powder industry according to some
experts. With unemployment in the
U.S. at historic lows, the employable
workforce has jobs and they have
options to jump to other jobs.
Turnover creates an endless need
for suppliers to provide constant
training and service packages to keep
equipment running. In some cases,
technology has to fill the gap when
there aren’t employees to maintain the finishing line. Therefore, the
need for robotics and intuitive
equipment that pushes information
to management in real time between
failures continues to grow.
Forecasting the Future
Gazing into the crystal ball,
powder application experts appear to
see evolution rather than revolution.
Most are working on technology that
addresses the challenges above and
approaching markets that make sense
for powder without tying up resources
chasing science projects. The focus
is on products that we believe will
lead the industry in technological
advancements and application
performance which are demanding
process solutions that spray less
powder, create fewer rejects, use less
labor, and increase productivity.
It is clear that innovation is alive
and well in the powder coating
application technology sphere. The
engineering stalwarts in the industry
are busy working away at incremental
advances in part visibility, powder
pump design, improved electrostatic
control and real time, remote feedback
loops. The industry is in good
hands with the strong commitment
of spray equipment designers and
manufacturers.
Kevin Biller is technical editor of Powder
Coated Tough and president of The
Powder Coating Research Group. He can
be reached at kevinbiller@yahoo.com.