arf@ddsw1.MCS.COM (Jack Schmidling) (05/06/91)
Foundry Problems This is more of a test then a quest for info. I don't quite know what trial means nor where this will end up. ............... I have a basement foundry and am having problems with switching from aluminum to brass or silver. A pattern that works well in aluminum will have voids when cast in brass or silver. The current example is a small bell (3 in high). I get voids when cast in silver or brass but a perfect bell in aluminum. I have the same problem with a small saucer but none with a similar condiment bowl that is about twice as thick. It would appear that the metal is not hot enough but my 2200 deg pyrometer is pegged when I pour. Any founders out there? arf ps p.s. If response by email.... please send to arf@gagme.chi.il.us arf
okunewck@psuvax1.cs.psu.edu (Phil OKunewick) (05/08/91)
arf@ddsw1.MCS.COM (Jack Schmidling) writes: > I have a basement foundry and am having problems with switching from > aluminum to brass or silver. > > A pattern that works well in aluminum will have voids when > cast in brass or silver. The current example is a small > bell (3 in high). I get voids when cast in silver or brass > but a perfect bell in aluminum. > > I have the same problem with a small saucer but none with a > similar condiment bowl that is about twice as thick. Sounds to me like the metal may be cooling as you pour it. Are you heating your mould enough before pouring? This may solve your problem.
vestal@SRC.Honeywell.COM (Steve Vestal) (05/08/91)
The fact that a thin saucer moulds OK in all three, but a think saucer doesn't, makes me wonder about whether it has something to do with cooling before the flow makes it everywhere. Some other things you might worry about: 1) do you have numerous or large enough risers to provide reserve fluid as the cast cools? 2) if you are sand casting, is your sand dry enough, or your melt not too hot, so that you don't get steam bubbles?