In PP and PE plastic cast film extrusion lines, melt pumps and dual-column screen changers form a synergistic core equipment combination that enhances production efficiency and product competitiveness by stabilizing process control, improving product quality, and ensuring continuous operation.
I. Melt Pumps: The “Heart Component” for Process Stability and Quality Enhancement
Precise Flow and Pressure Control
Through gear meshing or screw rotation, melt pumps maintain extruder melt pressure fluctuations within ±1% and achieve flow accuracy of ±1%. For instance, in biaxially oriented polypropylene (BOPP) film production, melt pumps reduce film thickness deviation from 5% in traditional processes to below 1%, significantly improving product uniformity.
Eliminating Upstream Fluctuation Interference
The melt pump's buffering effect substantially mitigates melt supply instability caused by uneven extruder feeding, temperature fluctuations, or screw pulsation. Its stable delivery ensures continuous melt flow into the casting die, preventing film breaks or abrupt thickness variations.
Energy Savings and Efficiency Enhancement
By shifting the extruder's pressure reduction function to itself, the melt pump enables the extruder to operate at lower pressure and temperature. This reduces mechanical energy conversion into heat, cutting energy consumption by 30%-50%.
Precise flow control eliminates additional energy consumption caused by pressure fluctuations while increasing extruder screw speed, shortening production cycles.
Broad Material Compatibility
Capable of processing thermoplastics (e.g., PE, PP) and high-performance engineering plastics, accommodating melts of varying viscosities (e.g., glass-fiber reinforced plastics with fillers exceeding 40%) while preventing melt fracture issues common in traditional screw extruders.
II. Dual-Column Screen Changer: The “Guarantee Shield” for Continuous Production and Filtration Efficiency
Non-Stop Screen Changing Technology
Featuring a dual-channel, dual-station design, one screen operates while the other is replaced. Melt pressure fluctuations during screen changes are controlled within ±1%, eliminating material interruptions and speed reductions caused by traditional single-screen changes. Production efficiency increases by over 50%.
High-Efficiency Filtration & Extended Lifespan
Filtration area exceeds traditional single-screen changers by over 30%, accommodating greater impurity loads. Filtration cycles extend by 30%-50%, reducing change frequency.
The main body utilizes high-strength alloy steel (e.g., H13 tool steel) with nitrided or coated surfaces, resisting wear from highly filled materials. Service life exceeds 5 years.
Multi-Material Compatibility
Suitable for conventional plastics like PE, PP, PVC, PC, PA, as well as specialty materials including fluoroplastics and bio-based plastics. Compatible with high-filler (filler rate ≤60%), high-temperature (operating temperature ≤400°C), and high-pressure (operating pressure ≤35MPa) conditions.
Flexible Filter Precision Adjustment
Quickly switch filtration levels by replacing mesh screens (20-300 mesh) to meet diverse requirements from coarse filtration (recycled material impurity removal) to fine filtration (optical-grade products).
Melt pumps and dual-column screen changers play irreplaceable roles in PP/PE plastic cast film extrusion lines:
The melt pump is central to process stability and quality enhancement, precisely controlling extrusion fluctuations and energy consumption;
The dual-column screen changer ensures continuous production and filtration efficiency, reducing maintenance costs through non-stop screen changes and high-efficiency filtration;
Their synergy enables large-scale production of premium cast films, meeting market demands for quality, efficiency, and environmental sustainability.
