The benefits of significantly faster startups and production rates both come from the ability to move significant amounts of air into and out of the blown film bubble.  A die designed to support IBC provides airflow passages for cold air coming into the bubble and hot air going out of the bubble.  A specially designed air distribution chamber sits on top of the die to deliver the cold air to the bubble surface.  The cold air contacts the bubble and transfers heat from the bubble to the air.  The hot air rises to the exhaust pipe, which provides the passage for the hot air to be removed from the bubble.  Two separate blowers provide the energy to move air into and out of the bubble.  A control system is required that measures the bubble size and adjusts the flow of the cooling air or the hot exhaust air in order to maintain the proper bubble size.  The IS-IBC1 control system uses an ultrasonic non-contact sensor to sense bubble position relative to the sizing cage.  Using a non-contact sensor eliminates gauge bands that result from using mechanical arms to sense the bubble position.  When the bubble is not the same size as the cage, the system adjusts the positive pressure inside the bubble to cause it to match the size of the cage.  When the bubble is sized properly, the system continuously adjusts the positive pressure to maintain the required size of the bubble.  The system also has a fine-tuning adjustment (cage contact) that allows the operator to make very small adjustments to the bubble size.  This feature is helpful in eliminating marks caused by the cage and also in making very small layflat adjustments. While the system is controlling the positive pressure to maintain size, approximately 300 to 3000 cubic feet of air per minute pass in and out of the bubble, which allows the film to cool more quickly and uniformly (the actual amount of air depends on the die size).  This dramatically improves production rate and quality.  It is like adding a turbocharger to your car; you will notice the difference.