Abstract
A riser equation considering the solid volume solidified during pouring is derived as follows : [Written in non-displayable characters.]where; Fct=Act/Vc2/3, shape factor of casting, Act=total surface area of casting including riser-casting contact area, Vr, Vc=Volume of riser and casting, K=(height of riser) / (diameter of riser), β=Fraction of solidification contruction (0.05 for steel), Vf=solidified volume in the casting during pouring. It is found that the adequate volume of riser decreases as the volume solidified during pouring increases. For a cube shape steel casting, pouring so as to make the ratio Vf/Vc be equal to 0.3, the riser determined from the equation behaved as the optimum riser. A riser equation is derived on a condition of pouring additional melt to fill the shrinkage cavity formed in the riser after the first pouring. The required volume of riser for additional pouring decreases by increasing the volume of solid solidified in the casting befere additional pouring.
