A 4 mm thick aluminum sheet of width w = 100 mm is rolled in a two-roll mill of roll diameter 200 mm each. The workpiece is lubricated with a mineral oil, which gives a coefficient of friction, μ = 0.1. The flow stress (σ) of the material in MPa is σ = 207 + 414 𝜀, where 𝜀 is the true strain. Assuming rolling to be a plane strain deformation process, the roll separation force (F) for maximum permissible draft (thickness reduction) is _________ kN (round off to the nearest integer).

Use:

$F=1.15\overline{\sigma }(1+\frac{\mu L}{2\overline{h}})$ wL, where $\overline{\sigma }$ is average flow stress, L is roll-workpiece contact length, and is the average sheet thickness