New auto gauge controls transverse direction film thickness

A five-year development project involving Mississauga, Ont.-based Techflow Design & Manufacturing Inc. has resulted in what’s being called a “re-envisioned approach” to controlling transverse direction film thickness in blown film extrusion lines, ensuring an on-time and uniform film gauge and up to a 50 per cent improvement in gauge variation.

The new TDK-500 Insta Gauge Automatic Air Ring – which draws on 40+ years of air ring design experience from Techflow; 30+ years of internal bubble cooling (IBC) controls design experience from D.R. Joseph Inc. of Arlington, Tex.; and 30+ years of thickness measurement experience from Kündig Control Systems of Ruti, Switzerland – has a tool-less access method for cleaning the narrow primary lip exit after process residues build-up, which helps to avoid partial air flow blockage.

Photo Credit: D.R. Joseph Inc./Techflow Design & Manufacturing Inc.

The TDK-500 improves on the implementation of airflow modulation for gauge control by using secondary lip air modulation where the velocity changes are more effective – leading, firstly, to a quicker reaction time and higher control resolution than primary lip air modulation; and secondly, permitting the primary lip to achieve its job of holding a stable bubble by isolating the primary lip cooling from the gauge control air adjustments.

The air flow from each control zone is constrained in an independent channel that extends to just before the secondary lip exit, eliminating eliminates zone cross-mixing and providing a more direct and effective control response to the film. Internal components are specified to the highest degree for consistent and reliable performance, even in harsh running conditions; and built-in safety features prevent damage and costly downtime.

The primary lip adjustment has been redesigned to facilitate set-up and reduce the intimidation factor of adjusting an air ring. The TDK-500 features a single adjustment point with a reference lever to adjust the primary lip. With the lower lip InstaSet control, operator anxiety is eliminated as they can quickly correlate the setting to bubble stability. Now, they can adjust air flow from minimum to maximum and back to mid-range in about five seconds, without concern of losing the bubble.

The unit was designed for easy component swap-out, and the entire lip set can be removed and replaced in a matter of minutes while the air ring remains installed on the extrusion die. Additionally, the TDK-500 control system can be integrated with the DRJ 3G IBC Control System for a single point of control for all bubble cooling.

Optional weight reduction is available for easier lifting from a patent pending 3D-printed polycarbonate cooling collar.