Ovality Control for Extruded Plastic Tubing

Tube ovality refers to the deviation of a tube's cross-section from a perfect circle — meaning the tube's inner or outer diameter is not uniform around its circumference. Ovality is typically caused by inconsistent internal air pressure during free extrusion. Precise air pressure regulation using ultra-low pressure controllers like MicroAir regulators directly minimizes ovality and keeps wall thickness consistent.

MicroAir regulators precisely regulate ultra-low internal air pressure — as low as below 1 inch of water — inside the tube during free extrusion. By maintaining a stable, consistent set pressure, the regulator keeps the tube's outer diameter uniform and prevents collapse or ovality. Models accepting contact closure or 0-10V inputs can respond automatically to signals from an OD gauge.

MicroAir I models use a manual 30-turn adjustment knob with standard response (~2 minutes to full scale). MicroAir II models add contact closure inputs for integration with diameter gauges, while retaining manual control. MicroAir IV models feature a voice-coil linear motor with 0-10V PLC input and high-speed response under 0.1 second, ideal for bump and taper tubing or fully automated extrusion lines.

Yes. Dual, 3-channel, and 4-channel MicroAir configurations provide independent pressure control for each lumen in multi-lumen tubing extrusion. Each channel can be set to a different pressure range with its own display, allowing precise simultaneous control of multiple internal air passages within a single stainless steel enclosure.

MicroAir regulators are available in ultra-low pressure ranges from 0–3 inches of water up to 0–5 psi, depending on the model. Some MicroAir I variants extend up to 0–30 inches of water. All units connect to normal factory compressed air regulated down to approximately 45–65 psi, and deliver precise ultra-low output pressure for free extrusion applications.

MicroAir IV models accept a 0–10 volt analog input, making them directly compatible with PLC systems, diameter gauge controllers, and other automated process control devices. This enables closed-loop diameter control, programmable bump and taper profiles, and full integration into modern extrusion line automation systems with response times typically under 20 milliseconds.