Kraft paper is produced on paper machines with moderate machine speeds. Kraft paper has many specifications as per requirement of consumer. paper must have tear resistance and water resistance properties so that it can be used in printing and packaging industries. Most important specifications of paper are GSM, BF, Cobb, RCT.
Following properties of paper are tested & verified in Gayatri Paper Mill
1 GSM Testing : GSM Testing Machine is used to conveniently calculate (grams / square Meter) of paper. GSM Testing consists of 2 instruments combination:
- GSM CUTTER: GSM Cutter is used to cut the fabric sample into exactly 100 Square cm piece as per Standards
- GSM WEIGHING SCALE: GSM Weighing Scale is used to measure weight of cut sample cut from Instrument no.1 – GSM CUTTER
2. Burst Factor : It is defined as the maximum pressure on the paper surface or paperboard in a perpendicular direction, required to rupture the paper. It is the strength characteristic of paper and estimates the behaviour of the packing in the process of transit like handling, loading and unloading. The bursting strength is one of the prime factors that determine the quality of the packing. There is always a quality stamp on the cartons to define the strength.
The formula to calculate the bursting factor of the paper or cardboard = Bursting strength (gf/cm2) / Grammage (gf/m2)
3. Cobb Testing: The Cobb test determines the amount of water absorbed into the surface by a sized paper, paperboard, and corrugated fibreboard paper or paperboard sample in a set period of time, usually 60 seconds (Cobb60). Water absorbency is quoted in g/m2.
The water absorbency of a material can have strong influence on printability and the setting rate of water based adhesives.
4. Ring Crush Test: The ring crush test (RCT) is used to determine the ring crush resistance of a paper strip formed into a ring with a standardized length and width.Ring crush testing is used to measure the edgewise compression of paper and board materials.
Results are quoted in kN/m.