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:: Production and Quality Assurance System

Rolls are tailormade products and therefore need careful production planning. Rolls are cast in chiller mould with a controlled allowance for contraction and machining. It is therefore necessary to have a mould of the desired size. A new mould is required to be made if oue is not available. After obtaining a order from a customer and a drawing for the reequired rolls, a method drawing for casting is made, according to which the mould for casting of the rolls is made. Melting of metal is carried out in any of the several induction melting units available as per requirement of metels. The melting charges are selected as per required chemistry of metal. Upon melting, samples are analyzed and necessary adjustments for various alloying elements made through additions of Ferro-alloys. Fracture tests are made and temperature measured to control the same through Immersion Pyrometeres. Metal is poured in the moulds through geared ladles of various capacities in pre-determined time to ensure clean metal in the mould.

After casting, the mould in alowed to cool for a pre-determined period of time before removing the cast roll from the mould. Then the cast roll is examined for casting defects and dimensional deviations, before sending the same for machining.

 
     

During machining, samples are taken for examination of microstructure and machining is allowed to proceed only if the microstructure is found propser. Hardness of the Rolls is checked on the Barrel surface as well as the fact of barrel ot check the depth of useful hardness. The machined surfaces are also examined for any surface defect like blowholes, inclusions, dross and cracks etc. Stage inspection of dimensions is carried out. A final diminsional check is carried out at the end of all machining operations. Once clearance is obtained from the Q.A. department, Rolls are ninally painted with anti-corrosive paint and packed for shipping.

Samples are also taken out preriodically from barrel of some Rolls to test the mechinical properties of Roll materials. All alloy steel rolls are ultrasonically tested for flaws and double poured Rolls checked for proper bonding between the Shell and the Core.