A single-screw extruder is commonly used for HDPE pipe production because it provides steady melting and smooth material flow. In the HDPE pipe manufacturing process, HDPE granules are heated and melted inside the extruder before being pushed through the die head to form the pipe. An HDPE pipe extrusion machine usually includes the extruder, die head, temperature control, cooling, and sizing systems. A complete HDPE pipe manufacturing machine can also include a haul-off unit, cutting machine, coiler, and printing system. In an HDPE pipe extrusion plant, these machines work together as one continuous production line. Twin-screw extruders can be used for other plastic processing applications, but single-screw extrusion is commonly used for standard HDPE pipe production.