Plastic particles, also known as plastic granules, serve as semi-finished products in the plastic molding and processing industry and are raw materials for molding processes such as extrusion, injection molding, blow molding, and foam molding. The manufacturing process of plastic particles, or the pelletizing process, indeed follows the steps outlined below: feeding, extrusion pelletizing, strip cooling, and strip cutting. Here’s a detailed explanation of these steps in English:
Feeding
In the modification production process, the primary component of plastic particles is resin, with the remainder being additives to achieve different functionalities. These materials are fed into the barrel of the pelletizing machine through a feeder. The feeding process requires precise control of material proportions and reduction of material layering to ensure the quality of the final product.
Extrusion Pelletizing
Extrusion pelletizing is a crucial step in the production of plastic particles. Within the barrel, the materials are conveyed forward, sheared, mixed, plasticized, and finally extruded through the rotation of the screw. This step determines the quality of the final product, as the mixing and plasticizing effects of the materials within the barrel directly impact the properties of the particles.
Based on the number of screws, extrusion can be classified into single-screw extrusion, twin-screw extrusion, and triple-screw extrusion. Different screw configurations are suitable for different materials and production needs. For example, twin-screw extruders are suitable for materials requiring high shear and mixing effects, while triple-screw extruders offer higher mixing efficiency and better material adaptability.
Strip Cooling
After mixing, the molten resin emerges in the form of strips resembling noodles through the die opening. These strip-shaped materials need to be cooled in a water tank. The cooling process is vital because the cooling speed and uniformity affect the shape and size of the final particles. Rapid or uneven cooling may lead to particle deformation or cracking.
Strip Cutting
The cooled strip-shaped materials are then cut into small particles, which is the cutting step. There are various cutting methods, broadly classified into cold cutting and hot cutting.
Hot Cutting: Cutting in the molten or semi-molten state. This method is suitable for materials with high melt viscosity, as they are easier to cut in this state. Water-cooled hot cutting is a common hot cutting method that uses a water cooling system to reduce material temperature while maintaining its molten state for cutting.
Cold Cutting: After being pulled into strips and cooled in a water tank, the materials are then cut into particles. This method is suitable for materials with low melt viscosity, as they maintain a stable shape and size after cooling.
Different cutting processes have different requirements for production line design and products. Therefore, the choice of cutting process needs to be considered comprehensively based on material characteristics and production needs.
Apart from the aforementioned steps, the production process of plastic particles may also include preparatory steps before formulation (such as cleaning, screening, drying, etc.), formulation weighing, kneading, and other procedures. These steps are equally important for ensuring the quality and performance of the final product.
In summary, the production process of plastic particles is a complex and precise one, requiring strict control of conditions and parameters in each step to ensure the quality and performance of the final product.
