The fluoroplastic extrusion melt pump is a precision device specifically designed for processing high-temperature, high-viscosity, and highly corrosive melts. Its core advantages lie in the corrosion resistance of fluoroplastic materials and the pump's precise conveying capability, making it widely applied in fields such as chemical engineering, fluoroplastic processing, and high-end pipe/film manufacturing. Below is an analysis from four dimensions: structural principles, performance characteristics, typical applications, and selection recommendations.
I. Structure and Working Principle
The fluoroplastic extrusion melt pump typically consists of a pump body, gears (or screws), shaft seals, a heating/cooling system, and a drive unit. Its core components are made of fluoroplastics (e.g., PTFE, PFA, PVDF) or metal structures lined with fluoroplastics to ensure superior corrosion resistance in areas contacting the melt. The working principle is based on volumetric metering: gears or screws rotate within the pump chamber, conveying the melt from the suction end to the discharge end through precise meshing gaps, achieving stable flow output. Some high-end models are equipped with a pressure feedback system that can adjust the rotational speed in real time to compensate for pressure fluctuations during extrusion.
II. Key Performance Characteristics
Corrosion Resistance
Fluoroplastic materials can withstand corrosion from most acids, bases, organic solvents, and oxidizing agents, making them particularly suitable for conveying melts of fluoropolymers (e.g., PVDF, PTFE), chlorinated polymers (e.g., PVC), and engineering plastics (e.g., PEEK).
High-Temperature Stability
The equipment can operate continuously at high temperatures ranging from 250°C to 400°C, with some models supporting instantaneous temperatures up to 450°C, meeting the demands of high-temperature melt processing.
High-Precision Metering
Through precise gear/screw design, flow control accuracy can reach ±0.5% to 1%, significantly improving the dimensional stability of extruded products (e.g., film thickness deviation <1%).
High-Pressure Output Capability
The discharge pressure can reach 30–50 MPa, suitable for long-distance conveying of high-viscosity melts or filling complex molds.
Low-Shear Characteristics
The gentle conveying method reduces melt degradation, making it particularly suitable for thermally sensitive or easily decomposable polymers (e.g., biodegradable plastics).
III. Typical Applications
Fluoroplastic Pipe/Film Extrusion
In the extrusion molding of fluoroplastics such as PVDF and PTFE, melt pumps eliminate pressure fluctuations from screw extruders, improving the uniformity of pipe wall thickness and film light transmittance.
High-Performance Engineering Plastics Processing
Used for the precise extrusion of high-viscosity, high-wear-resistant engineering plastics like PEEK and PPS, ensuring consistent mechanical properties of the products.
Cable Insulation Layer Extrusion
In the production of cross-linked polyethylene (XLPE) cable insulation layers, melt pumps stabilize melt pressure control, reducing surface defects such as "sharkskin."
Composite Material Co-Extrusion
By combining multiple melt pumps, laminated co-extrusion of different materials (e.g., fluoroplastics + engineering plastics) is achieved, meeting the stringent material performance requirements of industries such as aerospace and medical devices.
IV. Selection and Usage Recommendations
Material Matching
Select fluoroplastic types based on melt composition:
PTFE: Best chemical resistance but poorer wear resistance, suitable for low-wear conditions.
PFA: Balances corrosion resistance and wear resistance, suitable for melts containing particles.
PVDF: High mechanical strength and excellent temperature resistance, suitable for high-temperature and high-pressure scenarios.
Flow and Pressure Verification
Calculate the required pump displacement (unit: cc/rev) and maximum pressure based on extruder output, melt viscosity, and mold resistance. It is recommended to select models with a displacement margin ≥20%.
Shaft Seal Design
Prioritize double mechanical seals or magnetically driven seal-less structures to avoid the risk of melt leakage.
Temperature Control System
Equip with electric heating or heat transfer fluid circulation systems to ensure uniform pump body temperature (temperature difference ≤±5°C), preventing local melt solidification.
Maintenance Key Points
Regularly inspect gear/screw wear and recommend replacing wear parts every 2,000–5,000 hours. Use solvents compatible with the melt during cleaning to avoid cross-contamination from residues.
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