ROLLER MILL Roller mills are also known as reduction mills. Roller mills are mills that use cylindrical rollers, in opposing pairs or against flat plates, to crush or grind various materials, such as grain, ore, gravel, plastic, and others. Roller mills consist of two to five smooth rollers running at different speeds, so the grain size is done by the combined action of compression and shear. The grain size occurs mainly due to the pressure between the two or more rollers present in the mill. By the friction of the rollers the size is reduced and shows free flowing properties. Various rolling mills HISTORY The invention of the rolling mill is attributed to Leonardo da Vinci. The first rolling mills were shear mills, introduced from what is now Belgium to England in 1590. These passed flat bars between rolls to form an iron plate, which was then passed between slotted rolls (cutters) to produce iron bars. Subsequently this began to be re-rolled and tinned to produce tinplate. The shear mill was adapted to the production of hoops (for barrels) and iron with half-round or other sections by means which were the subject of two patents in 1679. Some of the early literature on rolling mills can be traced back to Christopher Polhem in 1761 in Patriotist Testament, where he mentions the History of using a hammer to tilt a single bar. Thomas Blockley of England was granted a patent for polishing and rolling metals in 1759. Another patent was granted in 1766 to Richard Ford of England for the first tandem mill. A tandem rolling mill is one in which the metal is rolled in successive stands, the Ford tandem rolling mill was for hot rolling of wire rods. Rolling mills...... at the center of the paper...... DISADVANTAGES: If the temperature of the workpiece is not uniform, material flow will occur more in the hotter parts and less in the colder ones. If the temperature difference is large enough, cracks and tears may occur. Roller deflection Maintain a Uniform spacing between rollers is difficult because the rollers deflect under the load required to deform the workpiece. Little or no effect on fiber materials.REFERENCES:1. Lieberman, Herbert A, Lachman, Leon (2009), Industrial Pharmacy: Milling Pharmaceutical Dosage Forms. Banglore, Pune. ISBN: 978-81-239-1679-8.2. Mehta RM, Pharmaceutics-I: Downsizing (1996), Page No: 90.3. http://www.feedmachinery.com/glossary/equipment/roller_mills.4. http://en.wikipedia.org/wiki/Rolling_(metalworking).5. http://www.directindustry.com/prod/neuhaus-neotec/roller-mills-pharmaceutical-industry-3759.