One plastic solution in mills that needs to be kept in mind are UHMW conveyor flights. Easily fabricated, these flights replace cast steel and have numerous advantages over the traditional material. To start, they are 50% of the weight of steel, which offers power saving benefits. The UHMW itself offers a much lower coeffecient of friction than steel and this plays into reduced power consumption as well.
Being plastic, they are easy to install and replace. The flights commonly come in 4-5″ heights with 12-36″ widths. They can be fabricated in-house by many distributors. If your mill is still using cast steel this is a proven plastic solution you really need to think about.