**6.7 Calendaring**

Calendaring is a process where a large amount of molten plastic is fashioned into sheets by passing the polymer between a set of rollers. The rollers are hot and keep the polymer in its semi-molten state. This allows the molten to be rolled many times until the desired thickness is reached. The sheet is then rolled through cold rollers to enable it to go hard and then wound up into rolls. Calendar for thermoplastics generally operates in four-roll units made up of three banks, each bank being wider than the preceding one. The advantages of calendar over extruder are the possibility of calendar to produce embossed films, sheets and laminates and the higher output than extruder. Examples of the final products are cling film, shrink film, clear, translucent rigid sheets for blister packaging and opaque flexible film.
