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The Paper Machine
Making paper is a complex process
and while the process itself depends on the desired final product,
the process is basically the same for all paper grades. The
paper machines basically have seven sections:
Headbox -- This is a machine that distributes
stock solution evenly onto the wire section.
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Wire Section -- This section is really a
woven plastic mesh conveyor belt up to 35 meters long
and is as wide as the paper machine itself.
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Press Section -- This section is made up
of heavy cylinders which squeeze out most of the water
that is in what is by this time almost a complete
sheet of paper.
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Dryer Section -- This section is a series
of pairs of cylinders which are at high temperature(just
above the temperature of boiling water) that the paper
is woven around until it is dry.
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Size Press(not shown in above diagram) --
This is a section that adds either a sizer(a solution
of water and starch), for printing paper, or a coater,
which is used to produce papers such as those found
in magazines.
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Calenders -- This section consists of hot,
polished iron rollers mounted in vertical pairs which
smooth the paper and give it its polished and glazed
finish.
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Reel Up -- This is sometimes called a parent
reel and is where the paper is rolled up so that the
paper can be cut into sheets.
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The first step in producing paper
involves the process of mixing water with wood and other fibers
in a stock preparation system. The resultant mixture is then
taken through a screening process, whereby the fibers are separated
from the stock solution and are transported to the headbox,
which in turn deposits the fiber matrix onto the wire section.
Here, the excess water is drained away to be recycled and used
later to produce more stock solution as well as to be used in
the screening process. By the time the fiber matrix reaches
the end of the wire section, it is paper, though it is of little
use at this point, and it is passed on to the press section,
where water is further pressed and sucked out. After this, the
paper moves to the drier section of the machine, where it passes
through a series of hot, steam heated cylinders, and is carried
by synthetic drier fabrics which help to completely dry the
paper. The paper exits the drier section and is then moved through
to the calender, where it is given a smooth finish, and then,
finally, the paper is reeled up, ready to be cut into seperate
sheets.
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