Mikro-ACM Air Classifying Mill

Mikro ACM® - Air Classifying Mills were invented by HMPS in the late 1960’s and are one of the most versatile types of size reduction equipment available in the market. These units while being capable of producing fine, medium and coarse grinds for a wide variety of materials for Food, Pharmaceutical, Chemical and Mineral industries, require very little maintenance over their life span. The basic design of these mills is the 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.

There are seven main factors which determine particle size distribution for the Mikro-ACM® 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. And lastly, the airflow governs the throughput as well as top size and fines generation. With the endless available options a machine can be configured to process just about any material that is below MOH’s hardness of 5.

Capacity: 20 grams to 20 tons/hour, D97 = 20 microns

Design & Options:

  • Grinds and Classifies in one machine
  • Laboratory (1 HP) to Production (600 HP) models available
  • Simple to clean, maintain and operate
  • Pressure Shock Resistant models available
  • Special Easy Access ACM design available for easy cleaning
  • Use with hot air for flash drying
  • Wear options: Stainless Steel, Ceramic or Tungsten Carbide
  • Compact and space-saving design
  • Cool and gentle grinding
  • Steep particle size distributions
  • Economical, efficient recovery of fine powders
  • Special Carbon Black Grit Reduction ACM available
  • Suitable for Chemical, Mineral, Food, Pharmaceutical & Cosmetic Materials

Watch a Video


See the New Easy Access Mill


Principles of Operation
The feed material is fed pneumatically to the Mikro ACM® Air Classifying Mill. Size reduction is a result of the feed material impacting against the rotating grinding elements and against the stationary liner. The beater edge speeds of up to 130 m/s make fineness values of d97=10 µm possible.

The feed material gets caught up in the air sucked through the mill by the downstream fan and is routed along the baffles of the shroud ring into the classifying zone. Here, separation into a coarse and a fines portion takes place on account of the two opposing forces and the different mass of the particles. The coarse material is rejected by the classifying wheel and is returned to the grinding zone, where it is ground again. The fines pass through the classifying wheel and exit the grinding chamber. The cut point is set as a function of the classifying wheel speed and can be adjusted even during operation.


Mikro ACM System