Types and Advantages and Disadvantages of Screen Changers

A screen changer is a manual or automatic switching device consisting of one or more filters. It is used to remove foreign particles and impurities as the plasticized material flows through the filters. It can be used to filter any type of polymer, rubber, or ceramic melt. A screen changer can be installed on any existing extruder, melt pump, reactor, or other extrusion line.

I. Core Functions and Applications

Screen changers are critical filtration devices in industrial production. Their core functions are as follows:

Impurity Filtration: Impurities (such as aging materials and non-plastic foreign matter) are intercepted by the filter in polymer, rubber, or ceramic melts to ensure product purity.

Ensuring Continuous Production: Supports manual, hydraulically automatic, or fully automatic screen changing modes, allowing filter switching without stopping the machine, avoiding production interruptions.

Process Optimization: The pressure generated by the material passing through the filter helps improve plasticization uniformity. Some models also feature a backwash function to extend filter life.

Intelligent Control: Precise screen changes are achieved through servo motors or pressure sensing systems. Some models can automatically trigger screen changes based on melt pressure or time thresholds.

Economic Benefits: Reduced downtime and material waste. Hydraulic automatic screen changers can achieve replacement speeds of as fast as 1-3 seconds, significantly reducing scrap rates.

Wide Application: Primarily compatible with equipment such as extruders and melt pumps, they cover over 20 industrial processes, including pelletizing, pipe forming, and film production. They are widely used in the plastics, chemical fiber, and ceramics industries.

II. Screen Changer Types and Features

1. Manual Screen Changer:

As the name suggests, this type relies on manual operation to change the screen.

Advantages: Small size, simple structure, easy installation, low cost, energy-saving and environmentally friendly, and no need for an additional power source. Easy operation and maintenance make them suitable for small businesses or production environments with low automation requirements.

Disadvantages: Screen changers generally require shutdown, impacting production efficiency. Slow screen change speeds and manual operation require high labor costs.

2. Hydraulic Screen Changer:

Advantages: Highly automated and easy to operate. Screen changes can be completed simply by controlling the hydraulic system. Screen changers can be performed without downtime, improving production efficiency. Disadvantages: Complex structure, high cost, requiring a dedicated hydraulic station, high requirements for hydraulic oil cleanliness and stability, and relatively high maintenance costs.

3. Plate Screen Changer:

Plate screen changers are divided into single-plate and double-plate screen changers.

Single-plate, double-station screen changers have two filter plates, enabling non-stop screen changes and improving production efficiency. Melt pressure remains relatively stable during screen changes, making them suitable for production lines requiring high production continuity, such as large-scale plastic product production.

Kitech Single-plate, Double-station Screen Changer: Features fast screen changes, large filtration area, high pressure tolerance, and easy operation. Its high-precision filter design allows for rapid, non-stop screen changes at temperatures around 300°C without compromising performance. It is an indispensable supporting equipment for extrusion lines for plastic sheets, plates, films, pipes, and pelletizing.

4. Column Screen Changer:

Column screen changers include single-column and double-column types. KiTech Double-Post Screen Changer: This screen changer features a dual-post cartridge structure with an extra-large filtration area, reducing screen change frequency and enabling non-stop screen changes. Its compact structure, easy operation, and minimal footprint allow for larger filtration areas and greater material flow rates, making it suitable for high-capacity, high-efficiency, and continuous operation of large-scale extrusion equipment.

Applications:

This dual-post cartridge screen changer is suitable for high-volume recycling and pelletizing of dirty materials, especially waste materials with high impurity content, such as PP, PE, PS, PA, and AB. Its high filtration accuracy, high production flow rate, and excellent stability make it suitable for medium- and large-scale production lines with high automation levels.

5. Kitech Laser Filter

KiTech's fully automatic laser screen changer eliminates the frequent screen changedowns associated with traditional manual screen changers, significantly reducing labor costs and ensuring uninterrupted factory production.

Utilizing advanced laser processing technology (with an accuracy of 80-800 microns), it effectively intercepts contaminants and eliminates the need for filter screens. Assisted by a dedicated scraper for thorough scraping, this high-frequency cleaning mode maintains high throughput even when granulating highly contaminated raw materials. Its core component, the laser screen, is constructed of 1.5mm thickened alloy steel, ensuring an exceptionally long service life and significantly reducing the frequency and cost of filter replacements.

Stable Constant Pressure Intelligent Operation:

The speed of the scraper and discharge screw automatically adjusts in real time based on melt pressure, ensuring constant pressure throughout the entire filtration process. This "constant pressure" operation enables the system to process highly contaminated materials stably and efficiently.

Extremely Low Melt Loss:

Only a minimal amount of melt is carried away during impurity discharge, keeping melt loss to an extremely low 1%-3%. Compared to traditional filters, this significantly reduces material waste and improves production efficiency.

III. Conclusion

When selecting a screen changer, you must comprehensively consider multiple factors, including production capacity, process requirements, and user preferences. Considerations include potential downtime, pressure fluctuations, and price. With the expertise and guidance of KiTech Machinery professionals, we can help you find the most suitable product, ensuring the continuity and efficiency of your production line.

IV. Upgrade Your Recycling Workflow Now!
As a leading manufacturer of plastic recycling machinery, Kitech Machinery offers end-to-end expertise. Contact our team for a free consultation or request an on-site demo to experience the KCP Series Pelletizer in action.

Our professional sales, technical, and overseas teams provide comprehensive support throughout the entire lifecycle—from pre-sales planning to post-sales maintenance.

Email: remond@kitechpm.com

Send an Inquiry: www.kitechrecycle.com/contact-us