Co Mill In Pharma

Co mill is one of the most important equipment used in pharma industries for  manufacturing of oral solid dosage forms.Co mill is also known as cone mill or conical mill.

Purpose Of Co Mill

The co mill is used for many purposes in pharmaceutical industries & some are given as below,

  • For sieving of dried granules.
  • For sieving of wet mass.
  • For crushing of tablets.
  • For breaking the lumps.

Co mill

For Sieving Of Dried Granules

The granules manufactured by wet granulation are dried & after drying the step of dry sieving is completed by the co mill to get uniform sized dry granules.

For Sieving Of Wet Mass

When the product is granulated the wet mass formed is passed through the co mill to reduce the size of wet mass.

For Crushing Tablets

Co mill is also used for crushing of the tablets during troubleshooting.

For Breaking The Lumps

Co mill or cone mill is also used to break the lumps in a granulated blend formed on long storage.

Material Of Construction (MOC)

The co mill is made of stainless steel grade 316L.

Principle Of Co Mill

Co Mill works on the principle of shearing & attrition.

Working Of Co Mill

The working of a co mill is very simple.The granules to be sieved are supplied to the sieving chamber from the storage tank fitted above the sieving chamber.

The particle size is reduced with the help of rotating impeller blades & this  material passes through the mesh installed in the sieving chamber.

The sieved material is collected in a container for further processing.

Components Of Co Mill

Following are the main components of co Mill

  • Product Holding Container
  • Sieving Chamber
  • Impeller Blades
  • Rotating Shaft
  • Mesh

Product Holding Container

Depending upon the model of co mill the feeding of material to the milling chamber is done through the product reservoir.

Product to be sieved is supplied to the reservoir or product holding container.

Fom this reservoir the material to be sieved is fed to the sieving chamber.

For some models the reservoir tank is not available & product is manually fed to the sieving chamber.

Sieving Chamber

The sieving chamber is the place where the process of screening takes place.It contains impeller blades, rotating shaft and sieve.

Impeller Blades

The co mill usually consists of three impeller blades.These impeller blades break down the particles which then pass through the mesh.The impeller blades may be of two shapes,

  • Square Bar Shaped 
  • Round Shaped 

Rotating Shaft

It is the main shaft which is connected to the motor.The impeller blades are rotated by this shaft.

The rotation of this shaft is variable & can be controlled from the operating panel.


A suitable sized mesh or sieve is attached around the impeller blades.The product after size reduction is passed through this mesh.

Advancement In Co Mill

The latest models of co mill are equipped with a pneumatic & lifting system.

The pneumatic system delivers granules directly from the fluid bed dryer or from any container to the product holding container & ensures operator & product safety.

The lifting system enables the co mill to lift it at any suitable height.

The lifting function is used to place a blender below the co mill after lifting it to a required height & sieved product is directly collected into the blender.

Advantages Of Co Mill

  • The noise level is very low.
  • Dust generation is prevented due to the close system.
  • Easy to operate.
  • The sieve change process is very easy.
  • It has high output.
  • It provides uniform particle size.

Image Credit

Image Source – Google | Image By – SaintyCo

Also Read 

  1. Oscillating Granulator
  2. Vibro Sifter 
  3. Pharmaceutical Questions and Answers.
  4. Potency calculation of Active pharmaceutical Ingredient.
  5. Easy Steps to calculate Double cone blender capacity.