New Digital Internal Bubble Cooling (DIBC) system from Addex Inc., Stoughton, Mass., is said to deliver the fastest reaction time in the industry to ensure precise bubble control, helping processors to speed product changeovers and significantly reduce scrap. The five-sensor system features a high-speed, servo-controlled air-regulation valve that performs split-second corrections in bubble size (up to 20 adjustments per second). Processors reportedly have switched from a 40-in. layflat to a 60-in. layflat in seconds instead of minutes. Addex also reports that at least one film processor has cut annual waste by more than 60,000 lb.
Patented split sensors enable the airflow intake and exhaust to react to the slightest changes in bubble size at or below the frost line where the bubble size is not yet set, particularly with low melt-strength resins like metallocene PE and LLDPE. Two non-contact ultrasonic sensors aimed at the bubble below the frost line allow for immediate correction by the intake/exhaust blowers via the AC inverter-controlled blowers. For more critical layflats, this is done via the high-speed servo reaction-control valve.
Two more ultrasonic sensors are aimed at the bubble above the frost line, where bubble size is stable, to calibrate the lower sensors and ensure the size is kept constant. The DIBC system includes a fifth ultrasonic sensor aimed at a fixed target in order to calibrate the other four sensors, whose readings can be altered by changes in air temperature.
The 100% digital circuitry eliminates errors caused by interference due to electrical devices like corona treaters or to ultrasonic sensor drift. It also ensures that the DIBC continues to function if one to three of the four ultrasonic sensors fail. However, in split-level set-ups, one sensor must function at each level.
The DIBC system is versatile because it can be used with 100% blower-speed control (recommended for trimmed films) and with air-valve control for the tightest possible layflat control.
User-friendly features include operator alerts that indicate an off-center or “breathing” bubble.The DIBC system can be integrated into any Addex or non-Addex line-control system.