Induction Furnace Overview - Revision history

ChuckH: /* Resonating Capacitors */

2018-10-15T21:10:52Z

Resonating Capacitors

← Older revision		Revision as of 21:10, 15 October 2018
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	If these high-power capacitors are to be made of local materials, the DIY Tesla coil community (e.g. [http://4hv.org/e107_plugins/forum/forum_viewtopic.php?60477], [http://wiki.4hv.org/index.php/Rolled_foil_capacitor_-_60_kV,_3.5_nF]) may have useful experience.		If these high-power capacitors are to be made of local materials, the DIY Tesla coil community (e.g. [http://4hv.org/e107_plugins/forum/forum_viewtopic.php?60477], [http://wiki.4hv.org/index.php/Rolled_foil_capacitor_-_60_kV,_3.5_nF]) may have useful experience.
	For oil-filled-paper designs, castor oil has a long history in HV pulse applications and canola[http://www.petroferm.com/datasheets/357_TDS.pdf] oil has become commercially accepted for power frequency applications. ([[Vegetable_Oil_Production \|Canola oil]] is also a likely candidate for [[Hydraulic_Fluid \|hydraulic fluid]].) Oil/paper may have dielectric loss factor ~1% (as opposed to polypropylene ~0.05%) so ~~pay attention to~~ internal heating.		For oil-filled-paper designs, castor oil has a long history in HV pulse applications and canola[http://www.petroferm.com/datasheets/357_TDS.pdf] oil has become commercially accepted for power frequency applications. ([[Vegetable_Oil_Production \|Canola oil]] is also a likely candidate for [[Hydraulic_Fluid \|hydraulic fluid]].) Oil/paper may have dielectric loss factor ~1% (as opposed to polypropylene ~0.05%) so internal heating is a major concern and effective cooling is important. Thermal runaway is possible as loss factor increases with dielectric temperature.

	===Melt Chamber===		===Melt Chamber===

ChuckH: /* Power Supply */

2018-10-15T20:52:32Z

Power Supply

← Older revision		Revision as of 20:52, 15 October 2018
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	*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is a vertical-shaft one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]		*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is a vertical-shaft one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]
	*** [https://patents.google.com/patent/US2451954A Westinghouse high-frequency generator patent] for induction heating, 3kHz, 10kHz examples		*** [https://patents.google.com/patent/US2451954A Westinghouse high-frequency generator patent] for induction heating, 3kHz, 10kHz examples
	*** [https://patents.google.com/patent/US1583809A 15kHz generator patent] (not targeted to induction heating); magnetic structure similar to modern hybrid stepper motor		*** [https://patents.google.com/patent/US1583809A 15kHz generator patent] (not targeted to induction heating); magnetic structure similar to modern hybrid [[Stepper_motor \|stepper motor]]
	*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]		*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]
	*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs		*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs

ChuckH: /* Power Supply */

2018-10-15T20:49:12Z

Power Supply

← Older revision		Revision as of 20:49, 15 October 2018
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	*** up to ~1kHz with slightly-modified conventional automotive alternator [http://www.venselenterprises.com/techtipsfromdick_files/alternators.pdf][http://www.delcoremy.com/Documents/Electrical-Specifications---Selection-Guide.aspx] (e.g. Delco 30SI 16 pole @ 10000 rpm = 1333Hz), perhaps adequate for crucible melting applications. [http://www.thebackshed.com/windmill/FPRewire.asp Fisher Paykel washing machine motors] are 48- or 56-pole permanent magnet designs often converted to generators and might operate into the low kilohertz range.		*** up to ~1kHz with slightly-modified conventional automotive alternator [http://www.venselenterprises.com/techtipsfromdick_files/alternators.pdf][http://www.delcoremy.com/Documents/Electrical-Specifications---Selection-Guide.aspx] (e.g. Delco 30SI 16 pole @ 10000 rpm = 1333Hz), perhaps adequate for crucible melting applications. [http://www.thebackshed.com/windmill/FPRewire.asp Fisher Paykel washing machine motors] are 48- or 56-pole permanent magnet designs often converted to generators and might operate into the low kilohertz range.
	*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is a vertical-shaft one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]		*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is a vertical-shaft one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]
			*** [https://patents.google.com/patent/US2451954A Westinghouse high-frequency generator patent] for induction heating, 3kHz, 10kHz examples
			*** [https://patents.google.com/patent/US1583809A 15kHz generator patent] (not targeted to induction heating); magnetic structure similar to modern hybrid stepper motor
	*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]		*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]
	*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs		*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs

ChuckH: /* Yoke */

2018-09-04T04:23:09Z

Yoke

← Older revision		Revision as of 04:23, 4 September 2018
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	=== Yoke ===		=== Yoke ===

	In lower frequency furnaces, ~~it seems~~ a ~~cylindrical~~ iron ~~or steel~~ yoke surrounds the coil, forming part of the magnetic circuit, increasing coil power factor, and thus improving efficiency. ~~This Turkish manufacturer [http://web.archive.org/web/20100205092811/http://www.demora.com.tr/index.php/meltshop/induction-furnace/magnetic-~~yoke~~.html] uses 0.3mm (0.012in) thick laminated transformer steel for~~ the ~~yoke~~. See ~~also~~ the useful description of the art in [http://www.google.com/patents/US5247539 US Pat. 5247539]		In lower frequency furnaces, a laminated iron yoke surrounds the coil, forming part of the magnetic circuit, increasing coil power factor, and thus improving efficiency. The yoke also mechanically resists the large radial forces from the coil. See the useful description of the art in [http://www.google.com/patents/US5247539 US Pat. 5247539]

	Steel laminations begin to have high losses at the 1kHz frequency level and soft magnetic composites (e.g. iron powder [http://www.hoganas.com/Segments/Somaloy-Technology/Home/ Somaloy]) might be considered. The biggest problem seems to be that the powder needs to be compressed at 20-50 tons/sq in in order to get good magnetic properties. A bit much for the CEB! Also poweder cost is unknown.		Steel laminations begin to have high losses at the 1kHz frequency level and soft magnetic composites (e.g. iron powder [http://www.hoganas.com/Segments/Somaloy-Technology/Home/ Somaloy]) might be considered. The biggest problem seems to be that the powder needs to be compressed at 20-50 tons/sq in in order to get good magnetic properties. A bit much for the CEB! Also poweder cost is unknown.

ChuckH: /* Power Supply */

2018-09-03T20:39:02Z

Power Supply

← Older revision		Revision as of 20:39, 3 September 2018
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	** Limited frequency range		** Limited frequency range
	*** up to ~1kHz with slightly-modified conventional automotive alternator [http://www.venselenterprises.com/techtipsfromdick_files/alternators.pdf][http://www.delcoremy.com/Documents/Electrical-Specifications---Selection-Guide.aspx] (e.g. Delco 30SI 16 pole @ 10000 rpm = 1333Hz), perhaps adequate for crucible melting applications. [http://www.thebackshed.com/windmill/FPRewire.asp Fisher Paykel washing machine motors] are 48- or 56-pole permanent magnet designs often converted to generators and might operate into the low kilohertz range.		*** up to ~1kHz with slightly-modified conventional automotive alternator [http://www.venselenterprises.com/techtipsfromdick_files/alternators.pdf][http://www.delcoremy.com/Documents/Electrical-Specifications---Selection-Guide.aspx] (e.g. Delco 30SI 16 pole @ 10000 rpm = 1333Hz), perhaps adequate for crucible melting applications. [http://www.thebackshed.com/windmill/FPRewire.asp Fisher Paykel washing machine motors] are 48- or 56-pole permanent magnet designs often converted to generators and might operate into the low kilohertz range.
	*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]		*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is a vertical-shaft one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]
	*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]		*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]
	*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs		*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs

ChuckH: /* Power Supply */

2018-09-03T20:38:05Z

Power Supply

← Older revision		Revision as of 20:38, 3 September 2018
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	** Limited frequency range		** Limited frequency range
	*** up to ~1kHz with slightly-modified conventional automotive alternator [http://www.venselenterprises.com/techtipsfromdick_files/alternators.pdf][http://www.delcoremy.com/Documents/Electrical-Specifications---Selection-Guide.aspx] (e.g. Delco 30SI 16 pole @ 10000 rpm = 1333Hz), perhaps adequate for crucible melting applications. [http://www.thebackshed.com/windmill/FPRewire.asp Fisher Paykel washing machine motors] are 48- or 56-pole permanent magnet designs often converted to generators and might operate into the low kilohertz range.		*** up to ~1kHz with slightly-modified conventional automotive alternator [http://www.venselenterprises.com/techtipsfromdick_files/alternators.pdf][http://www.delcoremy.com/Documents/Electrical-Specifications---Selection-Guide.aspx] (e.g. Delco 30SI 16 pole @ 10000 rpm = 1333Hz), perhaps adequate for crucible melting applications. [http://www.thebackshed.com/windmill/FPRewire.asp Fisher Paykel washing machine motors] are 48- or 56-pole permanent magnet designs often converted to generators and might operate into the low kilohertz range.
			*** Commercial induction heating supplies in mid-20th century often used motor-generator sets. Here is one rated 50kW 3000 Hz from [https://www.chaski.org/homemachinist/download/file.php?id=59926&mode=view Ajax Magnethermics]
	*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]		*** >100kHz historically feasible with [http://en.wikipedia.org/wiki/Alexanderson_alternator Alexanderson reluctance generators]
	*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs		*** frequency controlled by varying shaft speed: frequency = shaft speed * pole pairs

ChuckH: /* Crucible */

2018-09-02T18:02:35Z

Crucible

← Older revision		Revision as of 18:02, 2 September 2018
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	'''Materials'''		'''Materials'''

	According to this [http://www.foseco.com/en-gb/end-markets/foundry/foseco-home-uk/ Foseco refractories] brochure[http://www.foseco.com/uploads/media/Furnace_Linings_Ferrous_01.pdf], steel foundry induction-furnace applications typically use alumina or magnesia refractories, while cast-iron foundries use high purity silica. This is related to acid/base chemistry of the melt.		According to this [http://www.foseco.com/en-gb/end-markets/foundry/foseco-home-uk/ Foseco refractories] brochure[http://www.foseco.com/uploads/media/Furnace_Linings_Ferrous_01.pdf], [[File:Furnace-linings-ferrous-01.pdf]] steel foundry induction-furnace applications typically use alumina or magnesia refractories, while cast-iron foundries use high purity silica. This is related to acid/base chemistry of the melt.

	Fireclay (which can be a natural alumina/silica clay) for making refractory crucibles must withstand the superheated molten steel temperature of >3000F. Fireclay [http://www.mineralszone.com/minerals/fire-clay.html] is temperature-rated by Pyrometric Cone Equivalent (PCE) [http://www.ortonceramic.com/resources/reference/cone_ref.shtml]; "High Duty" (>= PCE32) or "Super Duty" (>= PCE35) is needed for ferrous metals. Such fireclay has high alumina content. (See also [[Aluminum_Extractor/Research_Development \|Aluminum Extractor]] feedstock.)		Fireclay (which can be a natural alumina/silica clay) for making refractory crucibles must withstand the superheated molten steel temperature of >3000F. Fireclay [http://www.mineralszone.com/minerals/fire-clay.html] is temperature-rated by Pyrometric Cone Equivalent (PCE) [http://www.ortonceramic.com/resources/reference/cone_ref.shtml]; "High Duty" (>= PCE32) or "Super Duty" (>= PCE35) is needed for ferrous metals. Such fireclay has high alumina content. (See also [[Aluminum_Extractor/Research_Development \|Aluminum Extractor]] feedstock.)

Bill Carson: /* Crucible */

2014-09-22T15:20:05Z

Crucible

← Older revision		Revision as of 15:20, 22 September 2014
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	'''Separately made crucible'''		'''Separately made crucible'''
	* See: [http://www.engineeredceramics.com/products/crucibles-and-~~ladles~~.html Engineered Ceramics Service Guides]		* See: [http://www.engineeredceramics.com/products/crucibles-and-ladle-liners.html Engineered Ceramics Service Guides]
	<html><iframe width="320" height="240" src="//www.youtube.com/embed/jEKjLSz1ATw?feature=player_embedded" frameborder="0" allowfullscreen></iframe></html>		<html><iframe width="320" height="240" src="//www.youtube.com/embed/jEKjLSz1ATw?feature=player_embedded" frameborder="0" allowfullscreen></iframe></html>
	* DIY small crucible video [http://www.youtube.com/watch?v=E3my6-nxFjM&feature=player_detailpage]<br>		* DIY small crucible video [http://www.youtube.com/watch?v=E3my6-nxFjM&feature=player_detailpage]<br>

ChuckH: /* Crucible */

2014-04-05T23:12:51Z

Crucible

← Older revision		Revision as of 23:12, 5 April 2014
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	'''Separately made crucible'''		'''Separately made crucible'''
	* See: ~~Crucibles for Induction Melting - Guidelines for Selection and Use:~~ http://www.engineeredceramics.com/~~crucible~~.~~htm~~		* See: [http://www.engineeredceramics.com/products/crucibles-and-ladles.html Engineered Ceramics Service Guides]
			<html><iframe width="320" height="240" src="//www.youtube.com/embed/jEKjLSz1ATw?feature=player_embedded" frameborder="0" allowfullscreen></iframe></html>
	* DIY small crucible video [http://www.youtube.com/watch?v=E3my6-nxFjM&feature=player_detailpage]<br>		* DIY small crucible video [http://www.youtube.com/watch?v=E3my6-nxFjM&feature=player_detailpage]<br>

Elifarley: Text replace - "openfarmtech.org/weblog" to "blog.opensourceecology.org"

2013-07-02T17:24:18Z

Text replace - "openfarmtech.org/weblog" to "blog.opensourceecology.org"

← Older revision		Revision as of 17:24, 2 July 2013
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	==External Links==		==External Links==
	* [http://~~openfarmtech~~.org~~/weblog~~/?p=1373 Original Blog Post]		* [http://blog.opensourceecology.org/?p=1373 Original Blog Post]
	* [http://web.archive.org/web/20100816034057/http://www.uie.org/webfm_send/391 Technical basics and applications of induction furnace PDF]		* [http://web.archive.org/web/20100816034057/http://www.uie.org/webfm_send/391 Technical basics and applications of induction furnace PDF]