The sheet extrusion process is a continuous operation of melting and conveying a polymer in a heated screw-and-barrel assembly (an extruder). The homogenous melt is forced to flow through a flat sheet die from which it exits at the desired width and thickness. The molten sheet is wound through the nips of a three-chill-roll stack for thickness sizing and cooling. The solid sheet is then cooled further on a cooling conveyor while the edges are trimmed to final desired sheet width. The sheet is either rolled or sheared into sections for later use. For profile extrusion, the process is the same except that the homogenous melt is forced to flow through a specially shaped profile die from which it exits at the desired shape and thickness. It is later cut to a desired length or rolled for later use.

LyondellBasell offers both polyethylene (PE) and polypropylene (PP) resins for use in sheet and profile extrusion applications.