Head Pressure and Output Stability

摘要

In my June and July columns, I discussed how to use drag-flow and pressure-flow equations to analyze the performance of an extruder. Those same equations can be used to analyze certain output stability problems. If the output has a rhythmic surge, the cause is almost always a partially filled metering section. A specific length of fill in the metering section is required to provide stability. That length depends on the polymer viscosity, screw design and the head pressure.