Friday, 30 December 2011

Principle of Risering


Riser:
-          A riser or feeder head is a passage of sand made in the cope (mold) during ramming the cope.
-          The molten metal rises in the feeder head (or riser) after the mold cavity is filled up.
-          This metal in the feeder head (or riser) compensate the shrinkage as the casting solidifies.

Function of riser:
a)      The primary function of the riser (attached with the mold) is to feed metal to the solidifying casting so that shrinkage cavity is get rid of.
b)      A riser permits the escape of air and mold gases as the mold cavity is being filled with the molten metal.
c)      A riser full of molten metal indicates that the mold cavity has already been completely filled up with the same.
d)     A casting solidifying under the liquid metal pressure of the riser is comparatively sound.
e)      Riser promotes directional solidification.

Types of riser:
a)      Open riser
b)      Blind riser

No comments: