Cutter Mill

Cutter mill is a size reduction equipment consisting of a series of uniformly spaced knives (2 to 12 in number) attached to a horizontal rotor (rotating knives) which act against a series of stationary knives attached to the mill casing. The bottom of the mill has a screen attached to control the residence time of the particles inside the mill head.

Size reduction process involves successive mechanical sheering of the feed material with the help of sharp knife. Cutter mills produce coarse particles from

1. Dried granulations before tableting and

2. Fibrous crude medicinal/roots, barks prior to extraction

Particles size are determined by

a. Rotor size

b. The gap between the two (2) sets of knives

c. Screen/sieve

Although cutter mill may differ from one another in whether the knives are movable or fixed and in classifier’s configuration, two cutting mill subclasses have been identified:

1. Double runner disc mill

2. Single runner disc mill

Pharmaceutical uses of Cutter Mill   

1. It is used for milling tough materials

2. It is used to mill fibrous materials prior to extraction

3. It is also used to produce coarse particles from dried granulations before tableting.

Advantages of Cutter Mill

1. It is the best option of size reduction when impaction, attrition, or compaction type milling is not effective especially for tough, fibrous, or resilient materials.

2. It is easy to install, operate, and maintain.

3. The equipment is not expensive

Disadvantages of Cutter Mill

1. Cutter mill is not suitable for most pharmaceutical applications due to the formation of wide particle size.

2. It is not easy to clean after use.

References

• Ahmed F. Abdel-Magid, and Stéphane Caron (2006). Fundamentals of Early Clinical Drug Development: From Synthesis Design to Formulation. John Wiley and Sons, Inc., Hoboken, New Jersey.
• http://www.pharmainfo.net/book/pharmaceutical-machines/cutter-mill
• Martin J. Rhode (2008). Introduction to Particle Technology. John Wiley and Sons Ltd, Chichester, West Sussex, England.
• Sarfaraz K. Niazi (2009). Handbook of Pharmaceutical Manufacturing Formulations: Semisolid Products. Informa Healthcare USA, Inc., New York.
• Sud Sushant and Kamath Archana (2013). Methods of Size Reduction and Factors Affecting Size Reduction in Pharmaceutics. International Research Journal of Pharmacy. 4(8): 57-64.