Mikro ACM® Air Classifying Mills were invented by Hosokawa Micron Powder Systems (HMPS) in the late 1960’s and are one of the most versatile types of size reduction equipment available in the market. These air-swept mechanical impact mills have a dynamic air classifier designed to grind an extensive range of materials down to a D97 < 20 µm.
These units require minimal maintenance and are capable of producing fine, medium, and coarse grinds for a variety of materials for food, pharmaceutical, chemical, and mineral industries. The basic design incorporates impact size reduction that is coupled with an internal dynamic classifier which controls the outlet (product) particle size via recirculating the coarse particles back into the grinding zone.
Seven factors determine particle size distribution for the air classifying mill: When varied, the rotor type and speed combined with the liner and hammer count affects the production of fines. The separator type and speed affects the top size of the product. Lastly, the air flow governs the throughput as well as top size and fines generation. With a range of options, the machine can be configured to process just about any material that is below MOH’s hardness of 5.
Range of models and options
Mikro ACM® Air Classifying Mill is available in 15 model sizes from 1 HP up to 600 HP for small batches and large production systems. They offer narrow particle size distributions and wear options including stainless steel, ceramic, or tungsten. Due to the mill’s air-to-material ratio requirement, heat-sensitive materials can be handled without product degradation. When milling hygroscopic materials, conditioned inlet air can be used to reduce moisture in the system. In high-temperature drying applications, the bearing housing can be insulated and air purged to protect the bearings. The mill can also operate with chilled air for heat-sensitive materials to prevent build up and for more efficient grinding.
This video briefly discusses how to disassemble and reassemble the Easy Access version of the Mikro ACM. First, remember to disconnect all power sources. Open the mill and remove the inlet stub, the baffle shroud assembly, and liner with backing ring. Then remove the nut and washer to remove the rotor disc. The liner support ring is taken out and finally the classifier wheel is taken off the shaft. The operator now has full access to the internals of the mill. Wet (drain and plug available) or dry cleaning options are available.
To assemble, the classifier
wheel is installed first followed by the liner support ring and the rotor disc
assembly. Install the liner with backing ring, then the baffle shroud, and the
inlet stub. Close the mill and re-attach all bolts and connections.