Plastic Pelletizer: The Core Equipment for Recycling Waste Plastics

Ⅰ. What is a plastic pelletizer?

Plastic pelletizer is a special equipment that processes waste plastics into uniform plastic particles through melting, extrusion, cooling and cutting. As the core equipment in the plastic recycling industry chain, the pelletizer realizes the transformation of waste plastics from waste to renewable raw materials and is a key link in the plastic recycling economy.

Ⅱ. Why do we need to granulate waste plastics?

1. Standardized processing: convert waste plastics of various shapes into particles of uniform size for subsequent processing and use
2. Increase density: the particle form is smaller than the fragments, which greatly reduces the transportation and storage costs
3. Improve quality: remove impurities through melt filtration to improve material purity
4. Convenient processing: the granular material has good fluidity and is suitable for various plastic processing equipment
5. Value enhancement: the recycled plastic after pelletizing can be sold directly as raw materials, and the economic value is increased by 50-300%


Ⅲ. Working principle of plastic pelletizer

The working process of plastic pelletizer can be divided into six main stages:
1. Feeding stage: pre-treated plastic fragments enter the extrusion system through the hopper
2. Conveying and compression stage: the screw rotates to convey the material forward and gradually compress it
3. Melting and plasticizing stage: the plastic is completely melted by external electric heating and screw shear heat
4. Filtration and purification stage: the melt passes through a multi-layer filter to remove impurities
5. Extrusion molding stage: the molten plastic is formed into strips through a porous die head
6. Cooling and pelletizing stage: After cooling, the plastic strips are cut into uniform pellets by a rotating knife.
In the whole process, temperature control, screw design and pelletizing system are key factors affecting product quality.


Ⅳ. Advantages of using plastic pelletizers for recycling

1. High efficiency: continuous production, processing capacity ranging from 100kg/h to several tons/h
2. Strong adaptability: various plastics can be processed by replacing the screw and die head
3. Energy saving and environmental protection: 70-80% energy saving compared to virgin plastic production
4. Controllable quality: recycled materials with different properties can be obtained through process adjustment
5. Good economic benefits: the equipment investment recovery period is usually 1-2 years
6. High degree of automation: modern pelletizers can achieve full automatic control

Ⅴ. Main types and applications of plastic pelletizers


1. Single screw cutting and compacting pelletizer
Structural features:
- Single screw design, simple structure
- Equipped with compacting silo to increase feed density
- Cutting system and extruder integrated

Working principle:
The material is pre-compressed in the compacting silo, and then evenly enters the single screw system. After melt extrusion, it is directly pelletized by the built-in cutting device.

Applicable materials:
- LDPE/LLDPE film
- Woven bags
- Slightly contaminated packaging materials

Advantages:
- Low investment cost
- Simple maintenance
- Suitable for small and medium-sized recycling enterprises

2. Two-stage single screw cutting and compacting pelletizer

Structural features:
- Two sets of single screws in series
- The first stage is mainly responsible for conveying and pre-plasticization
- The second stage completes the final plasticization and extrusion
- Equipped with compaction silo and strong cutting system

Working principle:
After the material is initially plasticized by the first stage screw, it enters the second stage screw to complete the final melting, and is extruded through the precision die head and then pelletized.

Applicable materials:
- HDPE bottle flakes
- PP strapping tape
- Mixed plastics with a small amount of impurities

Advantages:
- More uniform plasticization
- Large processing capacity
- Can adapt to a certain degree of material fluctuations

3. Single screw hard plastic pelletizer with side feeding system

Structural features:
- Reinforced single screw
- Side feeding system
- High torque drive
- Wear-resistant screw and barrel

Working principle:
The side feeding system is used to directly feed hard plastic fragments into the melting section to avoid feed blockage, and the high torque screw ensures that the hard plastic is fully melted.

Applicable materials:
- PVC pipe profiles
- ABS electronic product housings
- PC sheets
- Engineering plastic waste

Advantages:
- Solve the problem of rigid plastic feeding
- Wear-resistant design prolongs service life
- Suitable for high melting point plastics

4. Two-stage single screw rigid plastic pelletizer with side feeding system

Structural features:
- Two-stage single screw combination
- Side forced feeding
- First stage pre-plasticizing screw
- Second stage high compression ratio screw
- Enhanced filtration system

Working principle:
Rigid plastic enters the first stage screw for pre-plasticization through the side forced feeding system, and then enters the second stage screw to complete the final plasticization, and is extruded and pelletized after multi-layer filtration.

Applicable materials:
- Glass fiber reinforced plastics
- Engineering plastics such as nylon
- Highly filled PVC materials
- Composite plastic waste

Advantages:
- Processing of difficult hard plastics
- Stable product quality
- Modifiers can be added

5. In-plant single screw shredding and pelletizing extrusion system

Structural features:
- Integration of shredder and pelletizer
- Closed design
- Automatic control system
- Compact layout

Working principle:
Plastic waste enters the system directly and is first shredded, and then enters the single screw pelletizer through closed conveying to achieve instant recycling of scraps.

Applicable materials:
- Injection molding scraps
- Extrusion production line waste
- Blow molding product trimming materials
- In-plant clean waste plastics

Advantages:
- Realize instant recycling of production waste
- Reduce pollution and degradation
- Save transportation and storage costs
- Maintain stable material performance

6. Parallel twin-screw pelletizing extruder

Structural features:
- Two intermeshing parallel screws
- Modular screw design
- Precise temperature control system
- High torque transmission

Working principle:
The two screws are intermeshed, producing strong shearing and mixing effects. The material undergoes multiple segmentation and reorganization between the screws to achieve full plasticization and uniform mixing.

Applicable materials:
- Mixed plastic waste
- Filled modified plastics
- Masterbatch preparation
- High-performance composite materials
- Degradable plastics

Advantages:
- Good mixing effect
- Self-cleaning function
- High process flexibility
- Suitable for high value-added products

Ⅵ. Key points for selecting plastic pelletizers

1. Material characteristics: Select according to the type, shape and degree of contamination of the plastic being processed
2. Output requirements: From small 100kg/h to large 5000kg/h
3. Product quality requirements: ordinary recycled materials or high-quality special materials
4. Automation level: From basic control to fully automatic intelligence
5. Energy efficiency: Consider long-term operating costs
6. Site conditions: Equipment size and layout requirements
7. Budget range: From hundreds of thousands to millions

VII. Development trend of plastic pelletizing technology​

1. Intelligent control: Use AI algorithm to optimize process parameters
2. Energy-saving design: Efficient heating system and energy recovery
3. Modular combination: Flexible adaptation to different materials
4. Online monitoring: real-time quality detection and feedback control
5. Large-scale development: improve the processing capacity of a single machine
6. Specialized design: optimized models for specific plastics

With the improvement of environmental protection requirements and the development of circular economy, plastic pelletizer technology is developing in a more efficient, intelligent and professional direction, providing strong technical support for the plastic recycling industry. Choosing the right pelletizer equipment can not only improve recycling efficiency and quality, but also significantly improve economic benefits and promote the sustainable development of the plastic recycling industry.