Tiny Induction melting furnace

[Tim Williams]

"Mike Monett" <nospam@spam.com> wrote in message
news:426C02E8.6073@spam.com...

Is there any reason to go to the trouble and complexity? Why not just
pass 100A at 5V to terminals on the crucible and make it act like an
electric stove?

Well for one, fireclay (or alumina, magnesia, zirconia, etc.) needs voltages
a small bit higher than 5V to heat resistively. <BG>

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

 

[Mike Monett]

Tim Williams wrote:

"Mike Monett" <nospam@spam.com> wrote

Is there any reason to go to the trouble and complexity? Why not just
pass 100A at 5V to terminals on the crucible and make it act like an
electric stove?

Well for one, fireclay (or alumina, magnesia, zirconia, etc.) needs voltages
a small bit higher than 5V to heat resistively. <BG

Tim

Earlier, you said

"Absolutely...mind that the crucible is conductive. Moderate
resistivity is best, I wouldn't go with ferromagnetic materials
personally. Something like titanium would be good. Maybe 300 series
annealed stainless."

If the crucible is now changed to an insulator, how does it get hot from
induction?

Mike Monett

 

[Tim Williams]

"Mike Monett" <no@spam.com> wrote in message news:426C87BA.3748@spam.com...

Earlier, you said

:blink:

I changed the subject.

If the crucible is now changed to an insulator, how does it get hot from
induction?

For the application the thread needs (heating something nonconductive), you
need a susceptor. Might as well be the crucible, so make it something
nonreactive and conductive (like graphite or titanium).

Metal melting on the other hand has greater need of a refractory crucible,
especially since the metal is a good enough susceptor on its own. ;-)

Tim

--
"California is the breakfast state: fruits, nuts and flakes."
Website: http://webpages.charter.net/dawill/tmoranwms

 

[Daniel Haude]

["Followup-To:" header set to sci.electronics.design.]
On Sun, 24 Apr 2005 16:34:48 -0400,
Mike Monett <nospam@spam.com> wrote
in Msg. <426C02E8.6073@spam.com>

Is there any reason to go to the trouble and complexity?

Yes. It has been given in my original post but got snipped out of the
quotes.

For higher power we often use electron bombardment, and we might take that
route in this instance as well if inductive heating turns out to be
impractical.

--Daniel

 

[Mike Monett]

Daniel Haude wrote:

["Followup-To:" header set to sci.electronics.design.]
On Sun, 24 Apr 2005 16:34:48 -0400,
Mike Monett <nospam@spam.com> wrote
in Msg. <426C02E8.6073@spam.com

Is there any reason to go to the trouble and complexity?

Yes. It has been given in my original post but got snipped out of the
quotes.

For higher power we often use electron bombardment, and we might take that
route in this instance as well if inductive heating turns out to be
impractical.

--Daniel

OK, I found your original post in google:

"Induction heating (to about 300 C) would be elegant because it would
permit easy transfer of the crucible into and out of the chamber wihout
having to bother about electrical or thermal contacts for resistive
heating."

That makes sense - trying to get reliable contacts at high temperature
might be a problem.

However, your temperature is quite reasonable. How about a small heating
coil around the crucible?

And the next problem - regardless of the heating method used, how do you
monitor the temperature in order to control the heater?

Mike Monett

 

[Dirk Bruere at Neopax]

Mike Monett wrote:

Daniel Haude wrote:

["Followup-To:" header set to sci.electronics.design.]
On Sun, 24 Apr 2005 16:34:48 -0400,
Mike Monett <nospam@spam.com> wrote
in Msg. <426C02E8.6073@spam.com

Is there any reason to go to the trouble and complexity?

Yes. It has been given in my original post but got snipped out of the
quotes.

For higher power we often use electron bombardment, and we might take that
route in this instance as well if inductive heating turns out to be
impractical.

--Daniel


OK, I found your original post in google:

"Induction heating (to about 300 C) would be elegant because it would
permit easy transfer of the crucible into and out of the chamber wihout
having to bother about electrical or thermal contacts for resistive
heating."

That makes sense - trying to get reliable contacts at high temperature
might be a problem.

However, your temperature is quite reasonable. How about a small heating
coil around the crucible?

And the next problem - regardless of the heating method used, how do you
monitor the temperature in order to control the heater?

For 300degC all you need is some halogen lamps of the type used in cookers.

--
Dirk

The Consensus:-
The political party for the new millenium
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