foundry castings

[Richard Brekne]

Stephen Birkett wrote:

> > > ....Foundry castings need time to "cure" for strength....
> >
> >Do you have any technical reference for this? I've been trying to track down
> >solid information on the subject for some time--but to no avail.

I have to echo this experience. I wrote out all kinds of letters to must have
been a couple hundred places about iron used in piano plates and the two kinds of
approaches used most often today. I was really most interested in differences in
hardness  resulting from vacum casts vs wet sand or green sand casting. Couldnt
really nail anyone down on anything specific but there were lots of suggestions
that

1. The vacum process results in a harder iron, tho the "skin" may be harder in
wetsand casting.
2. The internal damping of wet sand is superior to vacum casts
3. Vacum casts are more precise, predictable and much quicker to cure
4. wetcasts can be given very long cool down periods and cure times to insure
that the iron hardens as evenly (without large airholes) as possible. This is
where the strength part comes in methinks.

None of this was clearly substantiated and I was not given any hard copies to
read. A few suggested that if I wanted to really know this stuff I should become
a metalurgist. :)

Interestingly enough... of the piano companies I wrote to about this only Yamaha
refused to answer any questions at all.

Not easy to track stuff down on this subject matter.

Cheers !

Richard Brekne
RPT, N.P.T.F.
UiB, Bergen, Norway
mailto:rbrekne@broadpark.no
http://home.broadpark.no/~rbrekne/ricmain.html