Classification of Plastic Pelletizing Lines

1. Classification by Feeding Method

2. Classification by Number of Extruders

3. Classification by Pelletizing Method

Some customers prefer water-ring pelletizing lines because they require less floor space.

The final configuration depends on the customer's requirements and 

raw material conditions. We recommend the most suitable solution 

based on these factors.

I. Introduction to the Compactor Feeding Pelletizing Line

The compactor feeding pelletizing line is a semi-automatic continuous production line 

mainly consisting of a belt conveyor, compactor, extruder, screen changer, water-ring 

pelletizing (or strand pelletizing) system, dewatering machine, pneumatic conveying 

system, and storage hopper.

Belt Conveyor

The belt conveyor continuously feeds materials into the compactor, ensuring a 

steady material supply while reducing the need for manual feeding.

Compactor (Similar in Function to an Agglomerator)

After plastic materials are fed into the compactor chamber, the high-speed rotating 

blades work together with the stationary blades to cut the materials into smaller pieces.

Under the centrifugal force generated by the rotating blade disc, the shredded 

materials move along the inner wall of the chamber. At the same time, the materials 

are continuously circulated and turned over by the rotating blades, moving from the 

outer edges toward the center of the chamber.

High-speed friction between the materials themselves, the chamber wall, and the 

blades generates a large amount of heat. As the temperature rises rapidly, the 

materials reach a semi-plasticized state and begin to stick together into small 

agglomerates.

Before the materials form large lumps, the guide plate directs them into the extruder 

for further melting, plasticization, and pelletizing.

The discharge outlet of the cutting compactor is directly connected to the extruder 

feed inlet. When the materials reach a semi-plasticized state through the shearing 

action of the rotating and stationary blades, they enter the extruder barrel through 

the feed opening.

Extruder

The rotating screw pushes the material forward through the barrel, where it is melted, 

plasticized, and finally extruded.

The screw rotation compresses, melts, and thoroughly mixes the plastic in pellet or 

powder form.

The barrel houses the screw and the plastic material. Its inner surface undergoes 

heat treatment to provide good wear resistance and a certain degree of corrosion 

resistance.

Heating elements are installed on the outer surface of the barrel, transferring heat 

to the plastic to facilitate melting and plasticization. Temperature sensors installed 

along the barrel allow automatic temperature control within a range of 0–300°C to 

meet different plastic processing requirements.

Water-Ring Pelletizing

The water-ring pelletizing system is primarily used for cutting molten plastic into 

pellets. The main shaft drives the blade holder at high speed, keeping the blades 

close to the pelletizing die.

The shaft speed can be adjusted according to the required pellet size, allowing 

pellets of different sizes to be produced.

After cutting, the pellets enter the circulating water ring, where they are cooled. 

The water and pellets then flow together through the water collection tray into 

the dewatering machine.

This process provides rapid cooling and helps prevent the pellets from sticking 

together due to insufficient heat dissipation.

Dewatering Machine

The dewatering machine is mainly used to remove water from freshly produced 

plastic pellets.

The high-speed rotating shaft generates centrifugal force, throwing the mixture 

of plastic pellets and water toward the screen. Water passes through the screen 

and is discharged, while some fine particles may also be carried out with the 

water.

The plastic pellets are conveyed by the dewatering rotor and discharged through 

the outlet for the next processing stage.

The bearings feature a water-cooling structure that improves heat dissipation, 

reduces bearing temperature rise, and significantly extends bearing service life.

II. Introduction to the Conventional Feeding Pelletizing Line

The conventional feeding pelletizing line is a semi-automatic continuous 

production line mainly consisting of a screw feeder, extruder, screen changer, 

water-ring pelletizing (or strand pelletizing) system, dewatering machine, 

pneumatic conveying system, and storage hopper.

Screw Feeder

The screw feeder is an auxiliary machine used in plastic processing. It 

automatically conveys crushed rigid plastics, powdered materials, or 

granular plastic raw materials directly into the extruder hopper.

Downstream Equipment

The extruder, water-ring pelletizing system, and dewatering machine 

work in the same way as those described in the compactor feeding 

pelletizing line above.

Extrusion

The upstream equipment remains the same as that used in the 

water-ring pelletizing line. The main difference is in the pelletizing 

section.

The water-ring pelletizing system, dewatering machine, pneumatic 

conveying system, and storage hopper are replaced with a cooling 

water trough, air blower, strand pelletizer, pneumatic conveying 

system, and storage hopper.

Cooling Water Tank

The cooling water trough is used to cool the plastic strands extruded 

from the extruder.

The trough is filled with water through the water inlet and is equipped 

with four nylon support rollers. The first three rollers should be 

submerged in the water, while the fourth should be positioned above 

the water surface.

These rollers mainly guide the plastic strands. Each roller has circular 

grooves that help distribute the strands evenly and prevent them from 

sticking together during rapid cooling.

Air Blower

The air blower removes some of the surface moisture from the plastic 

strands after they pass through the cooling water trough, allowing 

them to enter the next piece of equipment more smoothly.

Strand Pelletizer

The strand pelletizer cuts the cooled plastic strands into small pellets.

It mainly consists of two sections: the rotary cutting section and the 

drive section. The machine uses a variable-frequency drive (VFD) to 

control the cutting speed, enabling stepless speed adjustment.