What are the different types of plastic extruders? Let us break it down: A plastic extruder is the primary piece of equipment on a plastic extrusion production line. Its main functions are to deliver uniformly plasticized molten material for extruding plastic products, ensure that the raw materials are thoroughly mixed and fully plastified within the process‑required temperature range, and supply the forming die with a steady flow of molten material at consistent pressure, thereby enabling smooth and efficient extrusion operations.

Plastic extruders can be classified into twin-screw extruders and single-screw extruders. Below, we will examine the differences between these two types of extruders.

The differences between twin-screw extruders and single-screw extruders:

Single-screw and twin-screw machines: one has a single screw, while the other has two. Both are driven by a single motor, with power varying depending on the screw configuration. The 50‑mm twin‑screw model typically requires about 200 kW, whereas the 65‑mm version needs around 37 kW. Production capacity depends on the material and the screw design; the 50‑mm twin‑screw can produce roughly 100–150 kg/h, while the 65‑mm twin‑screw delivers approximately 200–280 kg/h. A single‑screw machine, by contrast, achieves only about half that output.

Extruders can be classified according to the number of screws into single-screw, twin-screw, and multi-screw extruders. At present, single-screw extruders are the most widely used and are well suited for the extrusion processing of common materials. Twin-screw extruders, on the other hand, offer advantages such as reduced heat generation from friction, more uniform shear on the material, greater screw conveying capacity, more stable extrusion output, and longer residence time of the material within the barrel, which promotes better mixing.

Twin-screw extruders feature forced extrusion, high product quality, broad process adaptability, long service life, low shear rates that minimize material degradation, excellent mixing and plasticizing performance, and the capability to directly mold powdered materials. They are equipped with temperature auto‑control and vacuum degassing systems, making them well suited for producing pipes, sheets, profiled sections, and other molded products.

Single-screw extruders occupy a pivotal position whether used as plasticizing and pelletizing equipment or as molding and processing machinery, and in recent years they have undergone significant advancements. San’ao’s 3D‑printing‑filament single‑screw extruder features a screw diameter of 45 mm and delivers a throughput of 20 t/h.

The primary hallmark of the development of single-screw extruders lies in the advancement of their key component—the screw. In recent years, extensive theoretical and experimental research has been conducted on screws, resulting in the design of hundreds of distinct screw profiles. Common types include the separating type, shear type, barrier type,分流 type, and wave‑type screws.

From the perspective of single-screw extruder development, although single-screw extruders are already quite mature, the continuous advancement of polymeric materials and plastic products will continue to give rise to novel screw designs and specialized single-screw extruders. Overall, single-screw extruders are trending toward higher efficiency.

Twin-screw extruders exhibit excellent feeding characteristics, making them well suited for processing powdered materials. Compared with single-screw extruders, they offer superior mixing, degassing, reaction control, and self‑cleaning capabilities. Their advantages are particularly evident when processing thermally unstable plastics and polymer blends. In recent years, twin-screw extruders have undergone significant advancements abroad; a wide variety of designs have been standardized and commercialized, and the number of manufacturers has grown considerably. They can be broadly classified as follows:

(1) According to the relative positions of the two axes, they are classified as parallel or conical;

(2) According to the meshing sequence of the two screws, they are classified into meshing-type and non-meshing-type.

(3) Based on the rotational direction of the two screws, there are co-rotating and counter-rotating types; among the counter-rotating types, there are further distinctions between inboard and outboard configurations.

(4) Based on the screw rotation speed, there are high-speed and low-speed types;

(5) Based on the structure of the screw and the barrel, they are classified as either integral or modular.