To extrude a thermoplastic polymer, granules are fed into a heat-regulated cylinder inside which an endless screw is turning. Due to the combined effect of the kneading action and heat, the granules are turned into a homogenous mix looking like a paste which is then given the desired shape by the die.

Cast film extrusion is a continuous operation of melting one or more polymers through a slot die to form a thin film that will be conveyed to successive rollers with different functions such us cooling, film finishing, etc., and finally wound onto a roll.

Comparing with blown film, cast films perform better for thermoforming applications. Typical film thickness ranges are between 20-400 μm and width of 400-3,000 mm. 

Conventional materials, such as PE, PP or PS, have traditionally been used by the industry to produce containers and other plastic films that are obtained from fossil resources that, in many cases, due to multimaterial mixtures, cannot be easily recycled.

Dr Bio polymers, plastic waste can be valued as compost.