Melt pump for plastic woven bag production line
Application Solution for Melt Pumps in Plastic Woven Bag Production Lines
The core processes of plastic woven bag production lines are: raw material extrusion → film stretching → warp and weft weaving → cutting and sewing. The stability of melt pressure and flow rate during extrusion directly determines the uniformity of film thickness, strength, and the consistency of finished woven bag quality. Melt pumps (specifically gear-type melt metering pumps), as high-precision pressure and flow stabilizing equipment, significantly enhance production line process stability and product yield rates. Key application points are outlined below:
Applicable Production Stages and Functions
Plastic woven bag extrusion processes primarily employ two mainstream methods, with slightly differing melt pump application scenarios:
Flat Filament Extrusion Process (Mainstream Method)
Installation Point: Positioned between the single-screw extruder and the die head.
Core Functions
Pressure and Flow Stabilization: Eliminates the inherent “screw pulsation” of single-screw extruders, ensuring melt enters the die head at constant pressure and flow rate. This guarantees uniform film thickness during extrusion and maintains flat yarn strength deviation ≤3% after stretching.
Energy Savings: Reduces extruder backpressure and friction losses between screw and barrel, lowering overall energy consumption by 8%-15%.
Increased Production Capacity: Stable melt delivery prevents die blockages, allowing extruders to operate at higher speeds and boosting output by 10%-20%.
Coating/Laminating Process (Surface Film Coating for Woven Bags)
Application Position: Installed between the extruder and the coating die head.
Core Function: Precisely controls the extrusion volume of the coating melt to ensure uniform coating thickness (deviation ≤ ±0.005mm), preventing wrinkling and uneven thickness that could compromise composite bond strength.
Installation and Maintenance Guidelines
Coaxiality Requirement: The center axes of the extruder, melt pump, and die must be coaxial with deviation ≤0.05mm to prevent increased melt conveyance resistance or pump wear due to misalignment.
Insulation Measures: Equip pump bodies with electric heating rings or thermal oil insulation jackets. Set temperatures to match extruder melt temperatures (±5℃) to prevent melt cooling and solidification within the pump.
Filtration System: Install a screen changer (plate-type recommended) upstream of the melt pump inlet to filter impurities (e.g., carbon deposits, metal particles) from raw materials, preventing gear wear.
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