Some Basics of Rolling and Rolling Mills | ispatguruMay 30, 2013 . Three high mills for rolling heavy sections were introduced in 1853. Hot strip mill were developed in America in the first half of the twentieth century. Basic concept of the rolling. The arc of contact between the rolls and the metal is a part of a circle. The coefficient of friction is constant in theory, but in reality it.roller mill an understanding of components,Roller mill - WikipediaFive- and six-roller mills Six-roller mills have three sets of rollers. When using this type of mill on grain, the first set of rollers crush the whole kernel, and its output is divided three ways: Flour immediately is sent out the mill, grits without a husk proceed to the last roller, and husk, possibly still containing parts of the seed, go to.