The cast film process involves the extrusion of polymers melted through a slot or flat die to form a thin, molten sheet or film. This film is "pinned" to the surface of a chill roll (typically water-cooled and chrome-plated) by a blast of air from an air knife or vacuum box. The film quenches immediately and then has its edges slit prior to winding.
Because of the fast quench capabilities, a cast film generally has much better optics than a blown film and can be produced at higher line speeds. However, it has the disadvantage of higher scrap due to edge-trim, and very little film orientation in the cross-direction.
Cast films are used in a variety of markets and applications, including stretch/cling films, personal care films, bakery films, and high clarity films.
As in blown film, co-extrusion is also a growing process technology, which can provide additional functional, protective, and decorative properties.