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Paper
Making Process
The Process of paper making at Khanna Paper Mills involves
various phases & steps of converting Raw Material into a Finished
Product. The various phases involved during this process could
be summarized as:
- RAW
MATERIAL
- PULP
PREPARATION
- FORMING
SECTION
- THE
PRESS SECTION
- THE
DRYER SECTION
-
CALENDARING AND REELING
- WINDING
Applications: Paper of different QUALITY, different
GSM and GRADE can be used for various purposes like:
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For all Commercial Printing Business Communication,
Publications, Diaries, Books and Stationary. |
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For Calendars, catalogues, Annual Reports, Advertising,
Brochures & Pamphlets. |
1. RAW MATERIAL: The good
printing and writing paper require a source of long fiber pulp
for web strength. It is either purchase or produced on site.
Short fiber pulp is also needed for fiber bonding and to enhance
printability and paper formation. The combination of good long
fiber and short fiber pulp can be achieved by latest state of
the art dinking technology. In India getting good long fiber
from forest resources are very much scarce. Therefore to have
a good fiber blend, use of recovered fiber collected from imported
sources (containing soft wood long fiber) is the best long-term
option. KPM is making their own recovered fiber pulp by most
sophisticated dinking technology. The recovered paper is dinked
to achieve pulp of high quality. The dinked pulp is made by
removing ink and impurities by mixing and processing through
different equipments. After drinking, multistage bleaching is
done to get required level of brightness.
2. PULP PREPARATION: Pulp produced after bleaching
is being supplied to paper machine. Dyes are added along with
other paper making additives to achieved desired visual appearance.
The end result is "furnish" pulp prepared for paper machine
use. The exact mix of various pulp, depends on the grade of
paper being produced.
3.
FORMING SECTION: The conventional system of sizing
of writing and printing paper is to use Rosin and Alum at 4-5
pH range. This type of sizing is called "acid" sizing which
adversely affect the paper quality in terms of paper age, longitivity
and paper shade as well as strength and optical properties.
In order to overcome these problems, KPM has adopted alkaline
sizing in the line of World's latest development of paper sizing.
In alkaline sizing, as the name suggests the sizing of the paper
is done under alkaline conditions resulting improved paper quality,
KPM paper is much better in optical, physical properties along
with more permanence and better bulk, because of alkaline sizing
and good recycled pulp use. The forming section is where the
fibers are formed into a web. Furnish is diluted with water
to a consistency of 1% fiber to 99% water. Delivery system spread
the dilute mixture on revolving belt-like screen, referred to
as "wires " or "forming fibers" by Paper Makers. Many details
such as the speed of the wire and the speed at which the pulp
is delivered, are critical and closely controlled. The Pulp
fibers in the presence of water bond to other fibers. The tendency
of these fibers to form together in group is called "flocculation".
A great deal of sophisticated engineering is devoted to keeping
these fibers evenly dispersed until they are on the wire (screen)
and set is place. Success in doing this results in superior
web "formation". Excess water is removed to increase the consistency
of fiber mat from approximately 1% to 20% solids by the time
it leaves the forming section. Drainage is increased by using
a variety of "de-watering elements". This takes place in less
than 2 seconds on modern paper machines. Cultural grades of
paper are generally manufactured at a final moisture target
of 4% to 6% range. As paper moves through the machine, water
is removed by pressing after the web leaves the forming section.
4. THE PRESS SECTION:
Pressing is done to remove water, compacts the web and improves
strength. A press section works by using felts and vacuum devices
to remove water.
5. THE
DRYER SECTION: The dryer section of paper machine is
composed of one or more separately driven and pressurized sections
of dryers, which allow control over dryer temperature and web
tensions. Dryer felts support the sheet and maintain the close
contact between the sheet and the dryers to rapidly transfer
heat from the dryers to the web. The web enters the dryer sections
containing approximately 60% moisture and usually leaves at
4% to 6% moisture content. The moisture varies depending on
the efficiency of the press section (going into the dryers)
and specifications for the finished product (leaving the dryers).
6. CALENDARING & REELING:
The calendaring section of the paper machine gives the desired
finish to the web. Calendaring compacts the sheet and increases
smoothness. A higher degree of smoothness usually results in
better printability. Calendar stacks consists of smooth rolls
of varying configurations. Items such as roll compositions,
whether or not steam is used in the rolls, the number of rolls
and the types of control over these rolls all vary from paper
machine to paper machine. The paper leaving from the calendar
stack is wound into a large roll of paper referred to as the
"parent roll". Parent rolls are wound to the specific diameter
needed to produce subsequent "sets" of smaller diameter reels
to satisfy customer requirements.
7. WINDING: Winders convert parent rolls into customer
requested reels of specific width and diameter. They also make
the removal of defective paper possible, and are designed to
control the amount of tension wound into rolls. |
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