General information about the drying process
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Coating dryer
The dryer slide-in unit of a coating dryer contains the
IR radiators and other additional hot air nozzles. Hot
air is blown out of these nozzles and onto the coating
layer. The hot air heats the varnish and evaporates
the water content of the varnish. The hot air also
carries the air that is filled with water vapour away
from the print sheet. The hot air is supplied by an
additional blower which blows air through a heating
element. The heating output is infinitely variable. An
excess temperature switch prevents the temperature
in the heating element from exceeding the specified
limit.
Extended delivery
The extended delivery, unlike the conventional high-
pile delivery, allows a maximum of four dryer slide-in
units of different designs to be used. Therefore, the
extended delivery of the DryStar Combination is
equipped with a second IR dryer slide-in unit in addi-
tion to the normal configuration with hot air for even
faster drying and a circulating blower to increase
ventilation. This area of increased ventilation above
the print sheet is absolutely necessary for processing
dispersion varnishes with a high water content if you
want to achieve maximum drying capacity. An addi-
tional fan row in the sheet ascent reduces the odour
emissions (SM 74). Additional suction devices in the
delivery ensure the constant removal of the air filled
with water vapours and odorous substances from the
delivery.
Pile surface temperature
The pile surface temperature is a measure for the
drying state of the ink or varnish. It is recorded using
the pile surface temperature sensor. Certain set
points for the pile surface temperature must be
defined, depending on the grammage of the print
material, the quantity of ink or varnish and the
desired gloss effect.
The pile surface temperature is controlled at a
temperature b/– 2
C. Fine adjustments
up or down are permitted. This allows the drying
conditions to be optimally adapted to the process.
