glossary of terms
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When the world thinks of plastic films, it thinks of PET.

Polyester Film Manufacturing and Technology

Below is a brief explanation of the standard extrusion process used in manufacturing polyester film.

  • Polyester polymer grades (made in continuous process or batch reactors) are extruded onto casting drum (gives ultra smooth surface to plastic film).
  • Film is stretched in forward and transverse directions.
    • Sequential Draw process: the film's forward draw is over a series of precision motorized rollers; transverse or sideways draw uses diverging clips in a multiple zoned oven with tightly controlled temperatures.
    • Simultaneous Draw process: the film is drawn using precision controlled simultaneously diverging, and accelerating clips through a multiple zoned oven with tightly controlled temperatures.
    • In all processes, tension and temperatures are critical to final quality of the film.
  • Sophisticated scanners and control systems maintain process conditions at optimal point.
  • Advanced structures are made by extruding layers of polymer simultaneously and coating film as it is stretched.
  • Film is wound into large master rolls (can be slit to precision widths before delivery to customer).
  • Film thicknesses typically range from 1 micron to 350 microns.
  • Each asset usually designed for narrow range of thicknesses.
    • Offering complete range of films requires heavy investment in multiple lines (from $50 million up per line).


process flow illustration

polymer structure