PAPER RECKONER

PROPERTIES OF PAPER:

A. MACHINE AND CROSS DIRECTIONS

Paper has a definite grain direction due to greater orientation of fibres in the direction of travel of the paper machine. This grain direction is known as machine direction. The cross direction is the direction of paper at right angles to the machine direction

Long grain and short grain:

The sheet is in long grain if the larger dimension is parallel to grain (MD) direction. The sheet is said to be in short grain if the larger dimension is parallel to cross direction (CD).

2.BASIS WEIGHT (GRAMMAGE)

The Basis weight of paper is the weight per unit area. This can be expressed as the weight in grams per square metre(gsm of g/m²)

3.SIZING/COBB

Resistance towards the penetration of aqueous solution/water is measured by sizing or cobb values.
The Cobb size tester measures the weight, in grams, of water absorbed in a given length of time, normally one minute (GSM/Minute)

4. CALIPER:

Thickness or Caliper of paper is measured with a micrometre as the perpendicular distance between two circular, plane parallel surfaces under a pressure of 1kg/cm²

5. BULK

Bulk is the volume of the paper per unit weight and is expressed as cc/gm. It is the reciprocal of density (weight per unit volume), It is calculated from caliper and basis weight. Bulk = Caliper in microns / Basis weight in GSM

6. TEARING RESISTANCE

It is the amount of work done in tearing the paper through affixed distance after an initial out. Tearing resistance is more in cross direction than machine direction.

7. BURST STRENGTH/BURST FACTOR

The bursting strength is the resistance to puncture by a blunt object. The results are reported in pounds per square inch or kgs. Per square centimetre or kilo pascals required to take the sample to rupture. Bursting strength indicates a composite of strength and toughness. Hence, it is useful in testing for bag, wrapping papers and box boards where the paper is subjected to a stress similar to that exerted in the bursting tests.

8. TEARING STRENGTH /TEAR FACTOR/TEAR INDEX

Tear is the determination of the average gram force/milli newton required to tear a single sheet of paper through a specified distance after an initial tear has been introduced.

9. TENSILE STRENGTH/BREAKING LENGTH/TENSILE INDES:

Tensile strength is a measure of the force per unit width required to break a specimen in either the machine or cross machine machine direction.

10. CRUSH TEST::

The crush test is used to determine the compression strength of a material. The crush test also detects poor adhesive penetration spotty adhesion, and carton board with low bond strength.

B. PAPER BOARD PULP AND RELATED TERMS

1. machine direction:

That direction in a paper or a board corresponding to the direction of the flow of the stock.

2.Cross Direction

That direction in the plane of a paper at right angles to the machine direction.

3. Top Side:

The face of a web or sheet of paper or board opposite to the wire side.

4.Wire Side

The face of a web or sheet of paper or board which was in contact with the forming wire during manufacture.

5.Machine –finished (M.F) PAPER OR BOARD

Paper or board treated mechanically onthe making machine to improve the smoothness and uniformity of appearance on both sides.

6. Machine-glazed (M.G.) paper or board:

Paper or board which has had one side made smooth and glossy by dying in contact with a heated, polished metal cylinder which forms part of the drying section of the machine. The other side of the paper or board remains relatively rough).

C. USEFUL CALCULATIONS

1. To calculate the weight (in kilograms) of a ream containing 500 sheets of a give size in inches and gram weight (substance).

Ream wt= Length (inches) x Breadth (inches) x gram weight (gsm)/ 3100

2.To calculate the weight (in kilograms) of a ream containing 500 sheets of a given size in centimetres (cm) and gram weight (substance).

Ream Weight = (Length cm) x breadth (cm) x gram weight (gsm)/ 20000

3. To calculate the equivalent weight of different sizes of sheets; Multiply known ream weight by length and breadth of sheet, the weight of which is required, and divide the result by length and breadth of sheet the weight of which is known.

Ream Weight = {Length cm) x breadth of sheet of unknown weight / Length x breadth of sheet of known weight

4. To calculate the length of paper in reel in metres.

Length of paper= (Weight of reel kg) x 100000(metres) / Reel Width (cm) x gsm

5. To calculate the approximate number of sheets of a particular size

No. of sheets=Weight of reel(kg)x 100,00,000 / Substance(gsm) x width(cm)xlength(cm)

NEPTUNE IMPEX:

(IMPORTED PAPER DIVN AND EXPORT HOUSE)