[TheForge] Microwaving Metals From the Virtual Junkyard

Mon Jan 5 18:10:08 2004

Microwave ovens work by generating power, and something absorbing the
microwave power (for example food) and turning the "radiation" into =
heat.
Water or food absorbs well, as it's resistive (essentially).  Metal is
conductive.  Though it is possible to heat metal in a microwave, it is =
not
very resistive, will likely offend the magnetron, make it snap and pop, =
and
eventually the magnetron likely will die.  On the other hand, if there =
is a
crucible is being used.  And something resistive is a component of the
crucible (like graphite, a form or carbon, which makes a nice resistor =
to
absorb the power), then the crucible would heat up, and then heat up the
metal.  Still, watch it carefully and try not to offend the magnetron.  =
Any
kind of arcing sound is a not so good thing<G>.

I have found that if items are spaced up about 1-2 inches above the =
floor of
an oven, then the oven is much happier in life.

I repair microwave ovens at lunch for fun, and work with magnetrons =
(radar)
as a part of my work. =20

Side note:  The way that ovens give you partial heating is by turning =
the
magnetron on and off.  10 seconds on, 10 seconds off gives you half =
power.
While it is possible to use a lamp dimmer to lower the power out of a
magnetron, the filaments would also be lowered and it would suffer in =
the
long run.  The on/off sequence is much easier to do<G>.

Holler off line if you need details about magnetrons.

-----Original Message-----
From: [email protected] =
[mailto:[email protected]]
On Behalf Of James Binnion
Sent: Saturday, January 03, 2004 11:15 AM
To: [email protected]
Subject: Re: [TheForge] Microwaving Metals From the Virtual Junkyard

If you are interested in working in very small amounts (under 10 oz=20
of bronze) of metal it works. The first person to talk about this on=20
the web is a sculptor from either Australia or New Zealand 5 or 6=20
years ago he used a combination of refractory clay and a proprietary=20
mixture of ferrite and magnetite to make crucibles that would absorb=20
the microwave energy. He was melting bronze. In the past year Bill=20
Roberts over on Artmetal list did some experiments with it and melted=20
aluminum. There is no reason it will not work if you are willing to=20
screw around with the development. Microwave radiation is not=20
something to be careless with you can't see, smell, or taste it and=20
by the time you feel it you are already burned. You can get very=20
badly burned or even kill yourself  by being exposed to the microwave=20
energy put out by a 1 kw oven magnetron. The amount of heat you are=20
putting into the oven cavity can easily warp the box and break the=20
seals letting the microwaves out so be careful.
--=20
Jim Binnion

James Binnion Metal Arts
Phone (360) 756-6550
Toll Free (877) 408 7287
Fax (360) 756-2160
http://www.mokume-gane.com
[email protected]
Member of the Better Business Bureau
_______________________________________________
http://mailman.qth.net/mailman/listinfo/theforge
theforge mail list group photo site is http://www.photoaccess.com
Login:  [email protected]
password:  anvil
___________