Question

Riser aids in establishing proper temperature gradient so that __________ solidification takes place. both progressive and directional directional uniform progressive

Answer 1

Answer : directional solidification

riser aids in establishing proper temperature gradient so that
$\bold{directional}$ solidification takes place .
Manufacturing casting with high density is possible only when the solidification process in the casting is directional towards riser. directional solidification is a rule that solidification of the molten metal in a casting should occur in such a way that liquid feed metal is always available for that portion that is just solidifying