Typically, the manufacture of flat sheet film involves mixing three or more components with a single or twin extruder. The melt exits the extrusion head (flat film extrusion dye) as a thin, flat sheet. Multilayer extrusion heads are used when different raw materials are transformed into composite-layer film during the co-extrusion process.

The extrudate is fed immediately to the casting or cooling roller where it is processed into a flat film with the desired properties. The cooling roll rotates faster stretching the extrudate making it thinner and wider. An airbrush ensures contact with the cooling roll while the neck is held to preset limits through various electrodes and air nozzles.

If the surface must be embossed, an embossing roller is used instead of the casting roller to acquire the desired results. A cooled silicone roller presses against the embossing roller to produce the desired design effect.

After casting, the film is measured for thickness. The extrusion head and speed of the extruder, melt pump or various rollers can be adjusted automatically or manually if necessary. For sheets needing higher tear strength or greater transparency, the sheets can be stretched to orientate the molecular structure to one direction (machine direction) or to two directions (bi-axle). This step is carried out either simultaneously or consecutively.

During orientation of the machine direction, the cooled and stabilised film is heated to optimal temperature and stretched by passing through a series of closely located rollers. The stretching effect can be precisely varied by adjusting the speed settings. When necessary, additional rollers can be mounted prior to discharge.

For orientation in the cross direction, a process is used in which the film is pre-heated and stretched in the pinch and tempered in various applications. Because several sheets must be pre-treated for later printing, coating, laminating, etc., a Korona discharge system is sometimes installed at this point.

Finally, the film passes through a cutter and is coiled onto a core. To minimise loss of material, waste produced from cutting is ground and fed back into the extrusion system. This is also one of the major areas of operation for the twin screw application because the operation mode vastly facilitates "fluff" processing. This leads to a percentual higher incidence in fluff relative to comparable single screw processes.