INDUCTION HEATING PROBLEM
INDUCTION HEATING PROBLEM
(OP)
I recently installed an Induction Heater for heating carbon steel bars .The heating coil sits about 7" over the 3/4" steel plate that supports it . The problem is the 3/4" plate is heating up to well over 200 deg f after just a few minutes of operation .What can be put between the coil and the plate to to minimize the the affects of the eddy currents . The unit runs at about 8 KHZ .





RE: INDUCTION HEATING PROBLEM
TTFN
RE: INDUCTION HEATING PROBLEM
RE: INDUCTION HEATING PROBLEM
"The amount of heating will depend on the field strength (and thus the amount of power running through the heating coil and how far it is from the material being heated), how quickly the field is changing (the heating coil power supply frequency), and the degree of coupling between the coil and what is being heated (how close the objects are to one another, what their geometry is).
kch
PS: or suspend it in the air.
RE: INDUCTION HEATING PROBLEM
RE: INDUCTION HEATING PROBLEM
h
So, I would guess that you can cover the steel plate with a 1/4 copper plate, maybe 4 sq foot or so in diameter, right under where the coil is operating. The induced currents will flow in the copper (which due to its lower resistance, will not heat up as much) instead of the steel, and you will be all set.
If you wanted to get fancy, you could cut some thru-slots in the steel plate, which will limit the flow of eddy currents also, but you will have to experiment with placement and size of the slots.
RE: INDUCTION HEATING PROBLEM
RE: INDUCTION HEATING PROBLEM
Use non magnetic stainless or aluminum 1" thick to knock down the field.
Fred Specht 847-606-9462
RE: INDUCTION HEATING PROBLEM
Do never forget that the materials we use for construction basicly are the same that we are going to heat or melt.
So you need to provide ad difference of several orders of magnitude in power density between laod and construction elements.
Sound design based on understanding the physical laws induction heating is based on is the best approach to avoid problems as you have expected.
RE: INDUCTION HEATING PROBLEM
This link shows that the skin depth of 60 Hz in copper is 8 mm:
http://en.wikipedia.org/wiki/Skin_effect
So if you have a time varying magnetic field, and if you had a thick copper plate, say 40 mm thick, over the steel base, would not the field die off as it passed into the copper plate,and almost none of it would hit the steel base? And since the copper is much more electrically conductive than the steel, those currents would cause less ohmic heating, and thus remain cooler?
RE: INDUCTION HEATING PROBLEM