Hot rolled coils pass through a pickling line, where scale breaker machines and hydrochloric acid solutions are used to remove any surface scale and/or oxide film that which causes surface flaws during the final stage of cold rolled steel processing.
Pickled coils are cold rolled in 4HI Cold Rolling Mill to a specified thickness, typically 40 to 90%, of original material dimensions. Fully automated shape adjustment is ensured through state of the art process machinery.
This is a highly productive manufacturing method whereby steel products with extra deep drawing qualities and high tensile strength can be produced. Two annealing methods are commonly used, batch annealing and continuous annealing.
This final rolling process is performed in order to remove minor surface defects such as stretch marks and to produce a smooth, lustrous surface. Skin Pass results in a further thickness reduction of about 10% maximum.