Working Principle of Plastic Extruders Manufactured by Hebei Shuangda
Time：
2017-05-17
The function of a plastic extruder is to convert solid plastics into a uniform, consistent melt through heating, pressurization, and shear, and then deliver the melt to the next processing step. Melt production involves processes such as blending color masterbatches and other additives, compounding resins, and regrinding. The finished melt is homogeneous in both concentration and temperature. High pressure is applied to extrude the viscous polymer. A plastic extruder accomplishes these operations using a screw‑driven barrel equipped with one or more screws. Plastic pellets enter the barrel through a hopper at one end and are conveyed by the screw toward the opposite end. To generate pressure, the depth of the screw’s flight decreases as the distance from the hopper increases.
The function of a plastic extruder is to convert solid plastics into a uniform, consistent melt through heating, pressurization, and shear, and then deliver the melt to the next processing step. Melt production involves processes such as blending color masterbatches and other additives, compounding resins, and regrinding. The finished melt is homogeneous in both concentration and temperature. High pressure is applied to force the viscous polymer through the die. A plastic extruder accomplishes these tasks using a screw‑driven barrel equipped with one or more screws. Plastic pellets enter the barrel via a hopper at one end and are conveyed toward the opposite end by the screw. To generate pressure, the depth of the screw’s flight decreases as it progresses away from the hopper. External heating, combined with internal heat generated by friction between the plastic and the screw, softens and melts the material. Different polymers and applications impose distinct design requirements on extruders. Design options include variations in the die outlet, multiple feed ports, in‑screw mixing devices, melt cooling and heating systems, or even designs without an external heat source (heatless extrusion), as well as adjustments to the clearance between the screw and the barrel and the number of screws. Compared with single‑screw extruders, twin‑screw extruders provide more thorough mixing of the melt. In tandem extrusion, the melt produced by the first extruder serves as feedstock for a second extruder; this approach is commonly used to manufacture extruded polyethylene foam.
Compared with other molding methods, plastic extrusion equipment for producing plastic products features advanced design, high output, excellent plasticization, low energy consumption, and hard-toothed gear drives. It also offers advantages such as low noise, smooth operation, high load capacity, long service life, high efficiency, and low unit cost.
Extrusion is primarily used for molding thermoplastic polymers, but it can also be applied to certain thermosetting plastics. It is widely employed in the processing of PVC, PE, PP, ABS, TPE, and other plastics. When equipped with various auxiliary machines, it enables the direct production of plastic products such as profiles, sheets, pipes, and pellets through plasticization and extrusion. Extruded products are typically continuous profiles, including tubes, rods, filaments, sheets, films, and insulation layers for wires and cables. In addition, extrusion can be used for blending, plasticizing and pelletizing, coloring, and compounding. Extruded products are referred to as “profiles”; those with non‑standard cross‑sectional shapes that differ from conventional profiles are called “special‑shaped profiles.”
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Shuangda
Hebei Shuangda Rubber Machinery Co., Ltd.
Tel：400-0319-386
Landline：+86-319-6017632
Email：shuangdaxiangsu@126.com
Official website：www.shuangdajx.com
Addr：Liyuantun Industrial Zone, Weixian County, Xingtai City, Hebei Province
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