Material can be reduced accurately while skin passing. Hot rolled steel coming from a steel mill or pickle line may need to be reduced 1% to 2% in thickness. This can be done on a coil-to-coil temper pass mill or in line on a cut-to length line.
There are many large rolling mills, including rolling mills that roll hot steel slabs 16” thick x 160” wide down to steel plate. When we think of reducing, we think of at least 20% thickness reduction per pass or many passes. In all cases, by reducing hot or cold metals, you improve its grain structure.
There are many types of coolants. Water is a good coolant, but is a poor lubricant. By adding extreme pressure soluble oil to water, you can have a very good coolant. However, this type of coolant can leave stains on the strip, which is not acceptable for many products.
In older rolling mills, a flying micrometer was used for gauge control. A flying micrometer is rollers in a C-frame. The rollers operate an encoder, which tells the position of the gap between two rollers. The micrometer is held perpendicular to the surface of the moving strip.
