3-High Rolling Mill
Three-high rolling mills consist of a large back up roll, small work roll, and another large back up roll. The purpose is to have a very minimum amount of reduction. Three-high mills are commonly used for making bearing material for gasoline and diesel engines.
Three-high rolling mills are also used to reduce costs for high reductions for expanded metals because large roll bend is possible with one of the work rolls. Three-high mills can also be used as a low cost skin pass mill and put into a cut-to-length or slitting line.
Reducing Coil-to-Coil
Theoretically, if you create enough tension to overcome the yield strength of the material within the uncoiler and recoiler tension reels, you can reduce the thickness without a rolling mill. If you apply a rolling mill with substantial tension input and output and hold the thickness accurately, you can make substantial reductions with a minimum amount of separating force. Using a tandem mill, tension can be created in between many stands by going from the first rolling mill to the second rolling mill. Each rolling mill inline creates tension at the next mill. Tension is not only used to reduce the separating force, but it is also very important in tracking the material through the mill. Without tension, the material with not go through the rolling mill straight and true.
Read about 2-high Rolling Mills and 6-high Rolling Mills.