Increase in casting yield by use of exothermic riser

Of all the methods known at present for reducing consumption of metals in risers, the most promising is the use of exothermically lined riser. Laboratory scale trials with gray iron castings have shown that an average of 80% yield can be obtained with such risers. The increase in casting yield will be higher with risers of larger diameters and on an average, about 20% increase can be expected. Though a burnt exothermic material has some insulating properties, it is less effective than materials like fly ash insulation purposes. (Shri G.N. Rao, Scientist and Shri P.R. Prasad, formerly Senior Research Fellow, National Metallurgical Laboratory)