In cast film production, polymers are melted through a slot or flat die (extruded) to form a thin molten film. This film is attracted towards the surface of a chilled roller using the force of an air knife or vacuum box, where it immediately solidifies. The film then passes through a series of chill rollers before being edge-trimmed and typically wound on a roll. Some machines will extrude a number of films for a laminated final product.
Detection of die "bolt heater" problems is necessary to ensure uniformity of the die temperature, control roller temperatures and to detect film breakages.
- Linescanner facilitates control of temperature of the melt curtain.
- Temperature measuring using spot sensor for downstream film temperature measurement optimizes final product quality.