Canning and Fish Packaging Technology

Unit 13 - Paper and Board

13.1.5.1.2.Carton making
There are 3 stages in carton making and distribution.

• Carton board is printed mostly in sheet form. The most popular printing technique being offset lithography.
• The next step is cutting and creasing. Here the carton blanks are cut out and the folding lines are made. The outer trim is then stripped off.
• The individual carton which is still flat is then passed through a folding and gluing machine at very high speeds, when a skillet is obtained.

Then the folding cartons (in the form of either blank or skillet) is supplied to the carton user in a lay flat condition.

The carton must be stiff enough to hold the contents without bulging. The bulged cartons are difficult to stack, will have poor appearance and the contents may leak out. The creasing operation is one of the important factors in determining the quality of a carton. The function of a crease is to weaken the structure of the board. Bowed sides are formed by creases that are too stiff compared to stiffness of the board. Sometimes the force with which a stiff crease tries to unfold is enough to force a glued seam open. If creases vary in its strength on one carton, some creases too stiff and some correct or weak, this may cause twisting of the carton, giving poor appearance and the carton easily falls over when stacked.

On the packaging line, cartons must be capable of being formed into shape rapidly and at the correct time. The ratio of crease to board stiffness is critical in this operation. If the main panel bows out side, this will hinder the top flap closure at high speed of the operation and if it bows inward, this can hinder insertion of contents.