Edge runner mill/Roller stone mill

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The edge runner mill is also called as roller stone mill which crushes the materials into fine powders by the rotating stones. The mill edge runner mill consists of two large rotating grinding wheels or stones turning slowly in a large bowl.

An electric motor in the basement provided power for the mill to start the device and used in flour mills.


An object for the invention of edge runner type or machine for crushing or grinding various substances or materials without the danger of clogging or jamming of the machine by accumulation of the ore with greater efficiency and in high comparative quantities.

Another object of the invention of edge runner type in which material can be crushed or ground in a continuous operation and in which the crushing is done by the heavy roller wheels or stones. This are roated in opposite to the direction of rolling of wheels and in which the material is fed into the chamber . so that due to the stones or wheels rotation the crushing of the materials takes place. The crushed powder is discharged through outlet. 1


The edge runner mill mainly works on the attrition and impaction by which the crushing or grinding of the powder material take place.

The crushing and the grinding of the materials takes place by the stones or the wheels present in the chamber.


Basic parts

It consists of two heavy rollers which are used for the grinding of the materials.

It rotates mainly on central shaft.


It consist of two heavy rollers and a bed made of stones or grainte. The roller have a central shaft and they revolve on its axis. The roller are mounted on the horizontal shaft and move around the bed. 1


The size reduction is done by crushing due to heavy weight of the stones and the shearing force which is involved during the movement of these stones.


The material to be grounded is put on the bed and with the help of the scrapper it is kept in the path of the stone wheels.

The material is ground for a definite period and then it is passed through the sieves to get the powder of the required size. 1


  • Very fine particles sized materials can be obtained by this edge runner mill.
  • Edge runner mill is used for grinding most of the drugs to fine powder, but it requires more floor space than the other commonly used mills.
  • It is used to crush or grind all types of the drugs


  • It is mostly used for all types of the drugs.
  • Very fine particle size is produced.
  • The major advantage of this mill is that it requires less attention during operation.
  • The various groups of elements and combinations of such elements produce a machine which operates with greater efficiency.
  • Utilizes less power, does not require any frequent clean up, it does not require any particular adjustment, it is simple in structure. 2


  • It is not use for sticky materials.
  • Noise pollution.


  1. Mehta RM, Pharmaceutics-I: Size reduction (1996), Page no: 117-118.
  2. http://link.springer.com/article/10.1007%252FBF02238723

About the Author

Saraswathi.B's picture
Author: Saraswathi.B

Assistant Professor in St. johns college of pharmacy

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