The average thickness of polyethylene films has been gradually decreasing over the years and this has been and it is a cause of various problems to any recycling line as thin films are more difficult to cut and grind,  have relatively higher contamination levels (higher surface areas) need more intensive washing and rinsing and require more energy for drying as they have an higher moisture level. 

On top, they can be made of various polyolefin polymers which are difficult to recognize and sort.


Thickness of film will also affect production rates meaning that, if you feed a 40 micron average thickness film and production is ,let's say, one ton per hour, with exactly the same line the productivity will be 750 Kg/hour with a 30 microns film, 500 Kg with a 20 microns and so on.


A recycling line will include a manual selection, shredding, pre-washing, washing and drying