Re: FW: [ATM] re Aluminium casting

[Woodchuck <djv@bedford.net>]

On Mon, 16 Aug 2004, Charles Mitchard wrote:

> Yes, you can check here http://home.c2i.net/metaphor/mvpage.html
> Use a silicon-carbide crucible to adsorb the microwaves, this heats up and
> melts the metal.
> Cant find anything about aluminium but dont see why not.

yeah, but I was asking about powder metallurgy, you don't actually
melt the powder, it just sinters together.  Done right it's as
strong as a casting. (Things like connecting rods in engines are
made with this process, I believe).  In this process, the powder
is loaded into the mould or die at room temperature, then that
is heated.

I've done a little reading and it seems a little too "high tech"
for backyard use.  Chiefly it's the need for pressure to pack the
die and possibly controlled atmosphere.

http://www.mpif.org/technology/whatis.html

Melting aluminum or brass and pouring it is a lot more within reach.

> >   Could it be done by microwave?  I would
> >like nothing better than to "cast" various parts (focusers, mirror
> >mounts, whatever) from powdered metal, if the heating part is
> >uncritical.  Surely it doesn't need a long soaking heat for small
> >(1", say) cross-sections?  Clearly the heat is below the m.p. of the
> >metal in question.
> >
> >Frankly, I'm scared of making a big cupola furnace and of handling
> >fifty pounds of molten metal at once.
>
> Why 50lbs?
> Thats a lot of metal for telescope making.

I was thinking of mount parts, and "infrastructure" stuff like
turntables of grinding machines.  (A 16" cast iron lathe faceplate
weighs in at 60 lbs.)  I'm sort of a fan of inertia, I guess.

Dave

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