Definition - What does Z-Mill mean?
A Z-mill is a machine for rolling steel. It allows the application of a higher roll pressure without bending the work rolls, which would result in poor metal quality.
The Z-mill uses cascaded supporting rolls instead of using a single pair of rolls to apply force on the small work rolls in the center. The Z-mill is designed to make heavy reductions at high speeds and used to roll both ferrous and non-ferrous metals. Very hard and elastic materials can also be rolled by Z-mill.
Z-mills are also known as Sendzimir mills.
Corrosionpedia explains Z-Mill
Z-mills are generally used for rolling of stainless steel and non-ferrous grades. These mills run at speeds ranging from 500MPM to 1000MPM. At such high speeds, it is essential that the material of rolls be of very good quality, clean and free from inclusions and defects.
A Z-mill is comprised of:
- Work rolls
- 1st intermediate rolls
- 2nd intermediate rolls
- Z-High mill rolls
- Back-up bearings
Z-mills operate with a work roll backed up by a number of rolls in a pyramid-shaped stack. This roll setup exerts extremely high forces through the work roll and yet keeps the work roll from flexing. The 2nd intermediate roll on the Z-mill also exerts a tension on the coil as it comes through the mill. The combination of high pressure and tension makes the mill capable of rolling material thin and flat.
A modern Z-mill configuration takes heavier reductions per pass and achieves thinner gauges. Harder materials can be rolled without intermediate anneals, and a better surface can be produced through this mill.