WPC extrusion line, with new process of co extrusion in 2024, is mainly used to produce the hollow or solid wood plastic composite profiles with two or three kinds of WPC material mixture from wood powder, HDPE plastic and processing additives. By the WPC and WPC co extrusion technology, the WPC plants can use cheap WPC materials for inner layer extrusion of WPC profiles, and high quality WPC mixture mateiral for extruding the outer layer of WPC profiles, but the required material quantity is less for outer layer of WPC.