Extrusion Line Pressure Control for High-Speed Production

Back pressure in extrusion refers to the resistance to melt flow within the extruder barrel and die, generated by the screw design, die geometry, and melt viscosity. It influences mixing quality and output consistency. For tubing extrusion, the internal air support pressure downstream of the die is separately regulated by precision instruments like MicroAir controllers to maintain dimensional accuracy.

Pressures inside an extruder barrel typically range from hundreds to thousands of psi, depending on material type, screw speed, and die design. However, for the internal air sizing cavity within extruded plastic tubing, pressures are ultra-low — often 0–3 inches of water to 0–5 psi — and require specialized regulators like OLC's MicroAir series to maintain consistent tubing diameter.

MicroAir regulators are available in a wide range of ultra-low pressure settings, from 0–2 inches of water up to 0–5 psi. The MultiAir 3-channel MicroAir I also supports extended ranges including 0–5, 0–10, 0–15, and 0–30 inches of water. Each channel can be configured with a different range to suit complex multi-lumen or profile extrusion requirements.

MicroAir regulators support three primary control interfaces: manual control via a precision 30-turn adjustment knob (MicroAir I), contact closure input from diameter gauges or external controllers (MicroAir II), and 0–10V analog input for PLC or automated system integration (MicroAir IV). The MicroAir IV also supports Dual State, Linear, and Manual operating modes.

MicroAir IV series regulators achieve a response time of less than 0.1 second — typically around 20 milliseconds for 50% of full scale — making them ideal for high-speed bump and taper tubing applications. MicroAir I and II series operate at standard response rates of approximately 2 minutes to full scale, suited for steady-state pressure regulation applications.

Yes. OLC offers dual-channel, 3-channel, and 4-channel MicroAir configurations specifically designed for multi-lumen tubing extrusion. Each channel independently regulates air pressure for a separate lumen, with each channel able to carry a different pressure range and its own digital display. This enables precise dimensional control of complex medical catheter and multi-lumen tubing profiles.