What are the different pelletizing methods in a plastic pelletizer?

A plastic pelletizer is a major auxiliary device in extrusion pelletizing equipment. Pelletizing auxiliary equipment can be divided into two parts according to its working method and function: hot cutting and cooling. Hot cutting can be further divided into dry cutting, water ring cutting, and underwater cutting, etc. Their specific working methods and application characteristics are as follows:

1. Dry Cutting: Dry cutting pelletizing refers to the process where the extruded strip material is immediately cut into uniformly sized pellets by rotating blades. The pellets are then transported to a cooling and screening device by a fan through pipes. This pelletizing method is suitable for the compounding and pelletizing of polyvinyl chloride (PVC) materials.

2. Water Ring Cutting: Water ring cutting pelletizing refers to the process where the extruded strip material is immediately cut into pellets by rotating blades and thrown against a high-speed rotating water ring attached to the inner wall of the pelletizing ring. The water flow then carries the pellets to a water separator for dehydration. After drying, the pellets are sent to a material cooling device for further cooling, resulting in the finished product. This production method is suitable for the compounding and pelletizing of polyolefin materials.

3. Underwater Pelletizing: Underwater pelletizing involves immediately immersing the extruded strip material in water for cooling, then cutting it into pellets. The pellets are then transported by circulating water to a centrifugal dryer for dehydration and drying. This pelletizing method is suitable for twin-screw extruders for pelletizing compounded raw materials and is used for large-volume production.

4. Cold-Cut Pelletizing: Cold-cut pellets refer to materials that have been compounded and plasticized by an extruder. After being formed into sheets from the die in front of the plastic pelletizer barrel, the sheets are first cooled in a water tank, then wound up, and finally pelletized using a dedicated pelletizer. This extrusion pelletizing method is suitable for pelletizing raw materials such as polyethylene, polypropylene, ABS, and polyethylene terephthalate.