only is reported to be an industry first.
With the high-power output of LEDs,
the primary limiting factor of the technology is the coating itself.
Akzo Nobel was the designated
coating supplier for this project. Akzo
Nobel agreed to a cooperation to develop a UV-LED curable process with
as much UV-LED as possible, without
affecting the coating price or properties. Efsen has been working with Akzo
Nobel, sharing not only the technical
expertise, but also using the chemical expertise of David Ivarsson, Efsen
chemist, who specializes in UV-LED
In direct contact with Akzo Nobel,
it was possible to develop a new curing
process, replacing all conventional UV
systems with the exception of mercury
lamps at the end of the production
line. A key decision to make this a reality was the choice of 365 nm LED for
the sanding position.
The normal coating process starts
with sealing of the surface with two
clearcoats, following up with sanding
the surface, and then proceeding to
build the color with multiple layers
of basecoats, and finally finishing it
off with a topcoat. The challenge has
been to find a process with only one
LED unit in each position, replacing
multiple conventional UV lamps on
The biggest difficulties to be considered have been the surface cure in
front of the sanding station. According
to Efsen, the coating must cure well
enough so it doesn’t clog the sanding.
Also, Freda will run both white and
dark gray base coats, which include ti-
tanium dioxide pigment that absorbs a
lot of the UV irradiation up to 400nm.
Efsen solved these challenges
together with Akzo Nobel by defining
the optimal LED wavelength on each
station, ensuring an optimum match
with the chemistry for optimal curing.
The final setup also uses height adjust-
able LEDs to adjust the gloss level of
the top coat.
With the low temperature of an
LED-cured process in combina-
tion with the full control of the UV
uniformity with Efsen’s proprietary
Efsen’s conventional UV lamp system, the WoodCure, provides guided cooling and
ICAD sensor recognizes deviations of the emitted UV power and adjusts the individual UV LED
arrays to produce a homogeneous UV-distribution.