In silicone tube extrusion lines, melt pumps serve as both precision pressure stabilizers and guardians of constant flow. By leveraging core advantages such as stable pressure delivery, precise metering, and melt homogenization, they significantly improve the dimensional accuracy, surface finish, and overall production efficiency of silicone tubes. As a result, they are essential standard equipment for the mass production of high-end silicone tubes and medical-grade silicone catheters.
Silicone raw materials generally exhibit characteristics such as high viscosity, strong thermal sensitivity, and shear sensitivity. Traditional single-screw extrusion processes are easily affected by fluctuations in feed rate, temperature drift, and backpressure changes, leading to pressure pulsations. This results in issues such as uneven wall thickness, eccentricity, rippling, poor surface appearance, and high scrap rates. Installing a melt pump addresses these common pain points in silicone extrusion at the source, enabling stable production, high-quality output, energy savings, and improved efficiency.
The Core Role of Melt Pumps in Silicone Tube Extrusion
1. Isolating Fluctuations and Stabilizing Melt Pressure for Smoother Extrusion
Melt pumps feature a positive-displacement, forced-feed design that isolates pressure fluctuations from the extruder upstream of the pump, delivering a stable and continuous flow of silicone melt to the die. Outlet pressure fluctuations can be controlled within **±1%**, effectively eliminating pulsations, striations, and wall thickness variations, resulting in improved product concentricity and higher batch consistency.
2. Precise Flow Metering and Locking for Strict Control of Dimensional Deviations
The output flow rate of the melt pump is linearly proportional to its rotational speed. By adjusting the pump speed, the extrusion volume can be locked, enabling closed-loop online control of wall thickness. Compared to traditional extrusion, silicone tube wall thickness deviations are optimized from **±5% to ±8% to ±1%**, significantly improving yield rates and material utilization. This makes it ideal for the production of thin-walled, high-precision, medical-grade silicone tubing.
3. Secondary homogenization of the melt to enhance transparency and mechanical strength
During the forced conveyance via gear meshing, the silicone melt undergoes further dispersion, homogenization, and degassing to eliminate bubbles. This reduces the presence of crystalline spots, air bubbles, and agglomerated impurities, resulting in products with improved light transmission, smoother inner walls, and enhanced tensile and pressure resistance. These products meet the stringent requirements of high-barrier applications such as medical, food, and water purification industries.
4. Reduced Load and Stress, Extending the Service Life of the Extruder
With the addition of a pump, pressure build-up is handled by the pump, allowing the extruder to focus solely on plasticization and mixing. The extruder operates at low pressure over extended periods, resulting in reduced wear on the screw and barrel, lower overall load, and an overhaul cycle extended to 1.5 to 2 times the original duration, leading to lower overall operating and maintenance costs.
5. Excellent high-temperature and high-viscosity compatibility, suitable for demanding silicone applications
The entire machine is constructed from high-temperature-resistant, wear-resistant, and corrosion-resistant materials, capable of withstanding operating conditions up to **400°C**. It is suitable for the continuous extrusion of high-temperature, high-viscosity, filled, and modified silicones, ensuring stable operation, minimal downtime, and excellent continuity.
6. Reduced Energy Consumption, Increased Line Speed, and Enhanced Production Capacity
Following process optimization, the line’s overall energy consumption has been reduced by 15%–20%. At the same time, maximum extrusion speed has increased by over 30%, making the line more suitable for powder-blended, color-matched, and co-extruded filled silicone applications. The longer it runs, the more energy-efficient and faster it becomes.
