The Bureau of Engraving and Printing prints paper bills 4 across and 8 down on sheets. When the sheets come off the printer they are shingled into a stack. The process is quite fast and keeping the sheets squared up is a challenge.
They have been using straps overhanging the feed point. As the straps wear, their coeffient of friction changes. Then the sheets become maladjusted. Using a model 110024 Super Air Knife, the guide straps were replace with an even airflow from the air knife. This proved to be a superior guide system because of the laminar flow. It also is maintenance free as it is not affected by wear.