In order to melt cast iron or other metals up to 1800oC and a small capacity
(up to 200 cc) in the crucible I want to build a small induction furnace. I
read recently in that it is possible to build such a low-frequency (50 Hz
mains freq ?) furnace which is powered from a household 230 V 50 Hz mains. Is
this true and how can I calculate the number of windings and the wire gauge
for the coil in order to build it ? Thanks in advance.
The problem is for decent efficiency you need high frequency or large
high power. Unfortunately I appear to have lost the details, formulae
but for 1 kg size you want more than 1KHz preferably 5-10Khz and several
of power, probably more than household supply.
The only real problem in getting these is getting appropriate capacitors
remembering that efficiency requires a resonant circuit and hence high
(parallel) or voltage (series). A friend has a 1.5 KW unit as part of a
analysis unit and the capacitor is unobtainible. The coil also needs to
water cooled (tubing).
The 50 Hz units are for industrial 100’s of Kg and 50 KW up. Experiments
50 Hz should not be carried out in the home.
For melting cast iron I have seen modeling books describe small blast
with a vacuum cleaner to provide the blast, these would probably do what
Incidently if anyone has the formulae or a pointer to a source for
heating I would appreciate a posting or email.
Associated Build An Induction Furnace Question: How do I build a small induction furnace? I want to cast iron and steel up to 30kg at a time.
- Answer:An induction furnace includes a crucible having a plurality of cooled metallic segments (6A, 6B) electrically insulated from each other and an electromagnetic induction coil (5) arranged around the crucible, wherein the electromagnetic induction coil is energized with low frequency electric current. Each of the metallic segments forming the crucible wall is made of a relatively thin sheet, and a cooling pipe is provided on each segment. The cooling pipes (22) are welded or brazed to an outer surface of each corresponding segment. A refrigerant flows through each pipe in order to evacuate heat from the corresponding segment. The furnace further includes a magnetic core (8) disposed above and near the top surface of the charge placed in the crucible. This magnetic core provides local narrowing of the magnetic field lines, causing centripetal motion of the melted part of charge located at or near the top surface of the charge. A second electromagnetic coil arranged at an exhaust port in the crucible controls flow of melted charge through the exhaust port.
Associated Build An Induction Furnace Question: where can I find a used oil furnace induction unit?
I am trying to build a metal melting furnace. Any other advice is more than welcome.
- Answer:My guess is nowhere as it sounds like an oxymoron. Either it is an oil burning furnace or it is an induction furnace (electric). You have to consider how much metal you want to melt. If you don’t want to melt more than 2 or 3 pounds max, there are small induction pots available from jewelry supply stores. Though finding them used will be challenging, eBay and Craig’s list come to mind. In addition it depends what metal you want to melt. For lead a torch should be more than sufficient, but I don’t think you’ll be able to melt steel. If you want to melt large amounts of bronze for bronze casting occasionally I am sure it will be much more economical to attend a foundry class at an university with a foundry. If none is close you could also see if there is a local art foundry and if you either can pay them for their work or if you can work for them to pay for using the foundry as well. They only may consider the latter if you have a track record of good metal work (are you good with welding?)