Paper Technology Journal 17 - Voith

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PM 6 – Excellent Performance
from the Very Beginning
In the mid-1990s, Kappa Zülpich took a
decisive step to face the ever increasing
international competition by investing
in a new paper machine. Voith delivered
the PM 6 with a wire width of 5,600 mm
and a maximum production speed of
1,000 m/min at that time.
The machine concept comprises a horizontal
DuoFormer CFD with a high
drainage capacity, even at high basis
weights and speeds. The press concept
includes a tandem NipcoFlex press with a
single-felted second nip. The dryer section
was designed in close cooperation
with the customer and has some special
features, such as dryers with a diameter
of 2.20 meters and a ropeless tail transfer
system. At the time, Kappa Zülpich
was the first customer to use this type of
ropeless system for packaging papers
with higher basis weights, which had
been used exclusively for graphic papers
17/04
until then. A conventional size press is
used for surface treatment. A fully automatic
reel rounds off the well-tuned machine
concept.
The Long-Term Optimization
of PM 6
Together with Voith, the first strategic
optimization measures were taken in the
year 2000. Installing a double doctor at
the first dryer and coating several dryers
to prevent stickies or other sticky impurities
from adhering to the surface were
the first effective steps to be realized. In
line with the long-term optimization concept,
web stabilizers and ventilating doctors
were installed in the after-dryer section
in the following year, thus significantly
improving both web run and CD
moisture profile.
Another measure was to upgrade tail
transfer with optimized blow nozzle systems
in the pre-dryer section.
In September 2003, the most extensive
rebuild so far was carried out, with the
target to increase machine speed from
the previous maximum of 1,050 m/min to
1,200 m/min in the future, without impairing
technological sheet properties.
One of the key measures was to rebuild
the DuoFormer CFD to improve drainage
capacity and to adapt it to increased machine
speeds. The existing forming roll,
with a diameter of 1,260 mm, was replaced
with a new vacuum-augmented
forming roll with a diameter of 1,760 mm.
Because of the new, much larger forming
roll, the top wire suction box and its water
discharge channels on drive side, as
well as the bottom wire deflectors, were
modified.
In the press section, a new double doctor
system was installed at the plain bottom
roll of the second press nip which can be
pivoted completely for maintenance purposes.
Absolutely reliable doctoring is
now guaranteed in this critical area where