History
In the 1950s and 60s, the term air doctor was first used to refer to the non-contact method of debris blow-off using compressed air. The printing and textile industries were some of the largest users of air doctors at that time. They often needed wide paths of air from a compressed air system to control the thickness of liquids on a surface, or to blow debris off the surface of materials prior to the next process. Other terms used were air bar, air squeegee, air curtain, air jet, air blast, air blow off, air nozzle, air comb, air blade and air doctor blade. Today the most commonly used term is simply, air knife.
Although air knives powered by compressed plant air are used in a wide variety of industrial applications, industrial blower powered air knives have proven to reduce the energy usage versus compressed air knives by 50-75% for most applications. Blower powered air knife systems really came of age with the advent of the 1987 Montreal Protocol which started the clock on the worldwide phase-out of atmospheric ozone depleting CFC’s (chlorofluorocarbons) then used as cleaning agents in most industries.
Most of these solvent based cleaning agents simply evaporated which required no blow off or other drying methods. Although the printed circuit board industry was still in its infancy, it was among the first to initiate the conversion to aqueous and semi-aqueous based parts cleaning systems.
With nearly every existing and all future circuit board factories using the new environmentally friendly cleaning technology, they also needed a new method of drying the p.c. boards following their water-based cleaning to remove the solder fluxes and other contaminants. The trend away from other types of solvent-based parts cleaning to water-based cleaning for all other industries began soon thereafter. Additionally, the conversion to water based inks, paints, coatings, adhesives and other solutions used in all manufacturing sectors has resulted in the need for air knife dryers where none had previously existed. As a result of the Montreal Protocol and the worldwide industry compliance to meet its environmental stewardship mandates, the former niche business of air knives became an industry.
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