Melt Delivery Tube Geometry Influence on Atomization Vacuum Aspirator Pressure
Melt delivery tube setback and tip taper dictate atomization aspirator pressure, where sub-atmospheric suction prevents melt freeze-off and backpressure blowback.
Melt Mass Flow Rate
Meaning
An empirical measurement of the ease of flow of a thermoplastic polymer through a defined orifice under controlled conditions determines the suitability of materials for separator films or casings. In battery assembly and plastic extrusion, the melt mass flow rate tells engineers how easily a resin will flow during high-speed molding. This measurement represents the mass of polymer extruded in ten minutes at a specified temperature and load.
Material Selection
Molecular weight distribution and chain branching are the main internal factors that govern the viscosity of a polymer melt. A high melt mass flow rate indicates a lower molecular weight resin that flows easily.
Process Optimization
Controlling the temperature of the extrusion barrel allows operators to manipulate the flow rate of the material during manufacturing. When the melt mass flow rate is too low, the high pressure required to move the polymer can cause shearing and degrade the polymer chains. Adjusting the process settings to achieve the optimal viscosity ensures that the extruded film has uniform thickness.
This consistency is necessary for the reliable performance of the separators used in lithium-ion cells.
Quality Assurance
Standardized testing in accordance with ASTM D1238 provides a reliable method to verify consistency. This test ensures that the melt mass flow rate of incoming batches meets factory standards.