Characteristics and Applications of Plasticizing Pelletizers

A plasticizing pelletizer is a single-screw extruder that processes solid polymeric materials. In the polymer processing industry, the majority of single-screw pelletizers are plasticizing pelletizers.

The primary function of a plasticizing pelletizer is to melt and plasticize polymers while simultaneously performing pumping, pressurization, and thorough mixing and homogenization. To achieve melting and plasticization of the polymer, two common sources of thermal energy are employed: one is heat supplied by heaters that transfer thermal energy to the material through the barrel.

Another mechanism involves the conversion of mechanical energy generated by screw rotation into thermal energy in the material.

A plastic pelletizing machine that does not incorporate a heater is referred to as a self‑heating plastic pelletizer. In this type of pelletizer, the thermal energy required to melt the polymer is entirely supplied by the mechanical energy transmitted through the rotating screw. Such machines are characterized by a low length‑to‑diameter ratio of the screw and high rotational speeds. At present, self‑heating plastic pelletizers…

The number of pelletizing machines is limited, and they remain in the prototype development and pilot-production stages.

There are many types of plastic pelletizing machines, a reflection of their wide range of applications.

Based on their intended applications, plastic pelletizing machines can be classified into three types: pelletizing, fiber‑spinning, and molding.

1. The purpose of a plastic pelletizing machine is to convert polymer powders or irregularly shaped bulk materials into uniformly sized and shaped pellets through melt plasticization. After pelletizing, the material exhibits increased density, improved flowability, and a significant reduction in air content and volatile substances, with…

This helps reduce bubbles in the finished product. Furthermore, when extruding directly colored products, a two‑stage pelletizing process is also employed to minimize color variation and enhance color uniformity. The virgin polymer pellets and color masterbatch are remelted in a plastic pelletizing machine, thoroughly blended, and then formed into colored pellets.

Pelletizing. This method is suitable for products that require strict control of color variation, such as colored textile filaments. Depending on the requirements, the screw diameter of pelletizing extruders can be quite large; currently, some exceed 400 mm.

2. The purpose of a spinning‑plastic pelletizing machine is to melt, plasticize, and blend spinning polymers into a polymer melt that meets the requirements for spinning, which is then supplied to the spinning unit to produce filaments. This type of pelletizing machine is suitable for both short‑fiber and continuous filament melt spinning in synthetic fibers. Short fibers

For applications requiring higher output, the screw diameter is typically larger, generally ranging from 75 to 200 mm. Plastic pelletizing machines for filament production prioritize melt quality and therefore use relatively smaller screw diameters, usually between 45 and 90 mm. Spinning machines commonly employ large-diameter screws, with diameters ranging from 75 to 150 mm. The length-to-diameter ratio of spinning screws is…

Large, typically 25–32.

3. The purpose of a plastic pelletizing machine is to process thermoplastic polymers.

After being melted and plasticized, it is directly formed into plastic products with specific shapes and dimensions, such as pipes, sheets, films, tapes, monofilaments, coatings, laminates, profiled extrusions, and hollow articles. This processing method is characterized by its continuous operation and high production efficiency. Depending on the intended application, within a relatively broad…

Select the screw within the specified range. The screw diameter is 30–300 mm, with an L/D ratio of 20–40.