An Air Classifier Mill (ACM) can grind material into a particle size range of roughly 150 microns (100 U.S. mesh) and 40 microns (400 U.S. mesh). Similar to the Fitzmill and Pulva mill, the ACM uses a high-speed hammer / rotor assembly to perform the milling, but differs in the way it controls the outgoing particle size.
In the ACM, an air classifier is installed into the grinding chamber, which allows the appropriate particles to pass through and returns any larger particles back into the grinding chamber.