Ch. 5 Risering Flashcards
what are the three stages of shrinkage?
Liquid, solidfiaction, and solid
what is the function of the chill.
promotes directional solidification within certain areas of the mold using heat transfer( cooling down) the metal helps reduce shrinkage
what part of the mold will solilidify first.
part with the lowest cross-sectional area.
what is the function of the riser. also what is it’s alternative name
a resoiver of molten metal used to supply the mold cavity with metal during solidification in order to reduce shrinkage.
what material should external and internal chills be made of .
external material with higher thermal conductivity than casting alloy. internal same material
metal in chill should solidify
last
when making your gates cut to this part of the mold cavity
the thickest part
what should you add to your sprue to make it flow better? and have a wider target for pouring metal.
funnel
what usually happens in metal during solidification. when it cools down
the metal tends to shrink or contract
what happens to metals when they are heated up
the metal tends to volumetrically expand.
directional solidification
solidification that works from the farthest end of the casting to the sprue
in large cavities what happens with solidification
it takes longer
What is difference between open and blind riser
Open is on top of mold and in contact with atmosphere, blind is inside the mold
metal in the mold cools down relative to the blank
the thickness of the casting
what do risers do in cast iron castings vs nonferrous castings
risers easily compensate for the shrinkages in cast irons. in nonferrous casting due to the slower cooling rate making large shrinkage and also dispersed shrinkages it is more difficult for the riser to feed it. riser tends to evenly distribute the metal instead of eliminating the shrinkage.
