Extrusion is a processing method for manufacturing products with a consistent cross section shape and of inﬁnite length. The resin arrives from the feed hopper to the extruder, undergoes compression, heating and homogenization, and advances while rotating until it becomes melt at the end of the extruder. The thermoplastic melt gets its directionality and design from a die with a consistent cross section shape, located at the end of the extruder. It then ﬂows over cooled metal calenders and rolled onto cylinders suited for packing. The extrusion process takes place continuously, with no cessation.