Pass design for channel section in rolling mill?

All depends on the channel size, 7 or 9 passes required to reduce from a rectangular or square starting section. The bar is almost completely enclosed by the top roll in a "closed pass" sequence of grooves and the thickness of the web and flanges is progressively reduced. A control or edging pass before the finishing pass regulates the final flange length, area reduction in the last pass is minimal to avoid excessive pass wear.