Film casting is widely used to produce plastic films. The polymer is extruded through a narrow slit. After the die lip, the material is in contact with the air before reaching the rotating chill roll. The rotational speed of the roll imposes the drawing velocity on the film. Depending upon the material and the operating conditions, different widths and thickness profiles of the film are obtained. The design challenge is to obtain a uniform thickness across the largest width of the film since the non-uniform material along the edges is normally discarded or recycled.

Fluent CFD software has been successfully applied to modeling polymer flows within the die and the film casting process itself, including viscoelastic effects. The flow uniformity across the exit of the die can be studied as a function of die geometry, material properties and operating conditions. The thickness distribution and width of the cast film is also predicted.

Multilayer film casting simulations can also be performed using Fluent CFD software. The thickness distribution for each layer is calculated while taking into account the different rheological behavior, as well as different initial thicknesses for each layer.

Velocity vectors and contours of thickness distribution predicted for a film casting process.