THE PROCESS

Cold Rolling is the process of reducing the thickness (guage) of a hot rolled pickled steel coil through pressing and application of tension.

The reduction process is achieved through several passes in a reversing mill with an application of 800-1000 metric tonnes of roll force through hydraulic jacks.

The rolling is done to specified thicknesses as per customer requirements. The strip is oiled throughout the rolling process with rolling mill lubricants.

THE MILL

A 4–Hi reversing combination mill from Hitachi in Japan was set up in technical collaboration with Yodogawa Steel Works in 1982 bringing in a sophisticated and advanced state-of-the-art technology
to Kenya.

With this mill MRM pioneered the ultra thin gauge rolling for galvanised steel, extra deep drawing material for enamelling, deep drawing materials for tube making and drum manufacturing.

Strip thickness is measured by radioisotope gamma ray gauges and deviation signals corrected by actuating roll load control, adjusting back tension and roll gap with a set of protocol.

ANNEALING

In order to produce extra deep drawing and enamelling grade materials, it becomes necesary to anneal the cold rolled coils. This is done by heating the cold rolled coils to a temperature range of 600-7000C in an electric bell annealing furnace in a protective gas environment which imparts brightness and cleanliness to the strip surface.
The annealed coils are skin passed to supress yield point elongation and to prevent the material from stretching stains. Annealing also creates the desired surface finish to the product.

APPLICATIONS

With a production capacity of 100,000 tonnes per annum, this plant is the biggest producer of flat steel products in the region. cold rolled steel products are the most familiar and indispensable products for modern living. They are used in manufacture of galvanised, Aluminum coated, Aluminiun-Zinc coated and prepainted roofing sheets. Other common applications include interior partitioning and decorating, steel furniture, enamelware, drum manufacturing, tube making, automobile bodies and a host of other applications.