Compared to other molding processes, plastic extrusion molding has a low cost and is more efficient. The extrusion molding process uses thermoplastics and they undergo repeatedly melting and hardening, this allows the waste to be reused rather than be discarded. Raw material and disposal costs are lowered. According to the number of screws, it is divided into single-screw extruder, twin-screw extruder and multi-screw extruder.
1. Raw plastic is fed into a hopper - along with any colorants or additives - that feeds down into the extruder.
2. The beads flow from the hopper down through the feed throat, which dispenses them onto a large spinning screw operating within a horizontal barrel.
3. The beads pass through the barrel on the screw while being heated to the melting temperature specific to that type of plastic. By the time it reaches the end of the screw, the plastic is thoroughly mixed and has a consistency like thick bubble gum.
4. At the end of the screw, the extruded plastic flows across a screen and a breaker plate, which serve two functions. The screen removes any contaminants or inconsistencies in the plastic, and the breaker plate changes the motion of the plastic from rotational to longitudinal. Now its ready for die.
5. The die for an individual plastic profile is more than just a hollowed-out shape of the final product.