A cleaning mixture comprising polymeric resin pellets having a Rockwell R hardness of 85 to 140, water, and a surfactant salt comprising at least one of sulfonate salts, C.sub.6 to C.sub.36 carboxylic acid salts, or mixtures thereof, is used to purge the mixing device. The cleaning mixture has a pH of 6.0 to 9.0.

The invention relates to a method (100) for supporting the implementation of a process change from a manufacturing process (200) for manufacturing a first film material (201) to a subsequent process (210) for manufacturing a second film material (211) in an extrusion device (10). Furthermore, the invention relates to a computer program product and a system (1).