Induction heater May 07, 2017 10:36AM |
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Re: Induction heater May 07, 2017 07:56PM |
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Re: Induction heater May 08, 2017 08:46AM |
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Dust
really....
see [reprap.org]
no not changed much at all....
and from 2009 [builders.reprap.org]
Re: Induction heater May 08, 2017 09:08AM |
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Re: Induction heater May 08, 2017 09:35AM |
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leadinglights
I have recently made a first attempt at induction heating with mixed results. On the downside it seems to be hard to get a short thermal break with a stainless steel tube: I think that there will have to be an electrical insulator such as glass there - not so easy to make. On the upside, my nozzles have a female thread so the inductive heating goes right to the end and thermal control should be better.
I may try to work with coil shape or possibly a slug of magnetic stainless steel shrunk onto a non-magnetic tube but I am feeling a bit pessimistic about getting a short thermal break in any simple manner.
Mike.
Re: Induction heater May 08, 2017 11:10AM |
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Re: Induction heater May 08, 2017 11:30AM |
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Re: Induction heater May 08, 2017 12:53PM |
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the_digital_dentist
What is the advantage of induction heating over resistive heating that justifies its greater cost and complexity? How does the reliability compare?
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leadinglights
I will confess to having no more than a tenuous grasp of how induction heating works. If it was just eddy currents then most conductive materials should get hot - the few explanations why it is not eddy currents talk about hysteresis loss, but the old high permeability materials I was familiar with such as mu-metal have very narrow bh loops. Finding the "right" stainless and silver soldering it to the "wrong" stainless steel may work.
Mike
Re: Induction heater May 08, 2017 03:04PM |
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newbob
.......................................
Skin depth also varies as the inverse square root of the permeability of the conductor. In the case of iron, its conductivity is about 1/7 that of copper. However being ferromagnetic its permeability is about 10,000 times greater. This reduces the skin depth for iron to about 1/38 that of copper, about 220 micrometres at 60 Hz. Iron wire is thus useless for A.C. power lines (except to add mechanical strength by serving as a core to a non ferromagnetic conductor like aluminum). The skin effect also reduces the effective thickness of laminations in power transformers, increasing their losses.
Re: Induction heater May 15, 2017 11:16AM |
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Re: Induction heater May 15, 2017 12:32PM |
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newbob
I've done some more reading and I think I'll go with horseshoe inductor positioned on two sides of the nozzle instead of trying to squeeze enough coil around it. I'm also looking at ways of focusing the magnetic flux to direct it precisely at the end of the nozzle where I think it should be (I maybe wrong and may get oozing and not enough melting speed but I'm curious the outcome).
Re: Induction heater May 16, 2017 07:57AM |
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Re: Induction heater May 16, 2017 10:21AM |
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Re: Induction heater May 16, 2017 11:43AM |
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Re: Induction heater May 16, 2017 03:15PM |
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Re: Induction heater May 16, 2017 04:15PM |
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Re: Induction heater May 16, 2017 06:41PM |
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Re: Induction heater May 17, 2017 12:13PM |
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leadinglights
That is an instructive video but with care an inductive heater can be made with only a modicum of electronic knowledge. The main "gotchas" are that the Royer circuit needs a fast switch on and that the the type of capacitor is very important. Having said that, for hotend use in a 3D printer it would be nice to drive it with the same PWM input as used with a resistive heater. To use a PWM, or even a bang-bang control will need the the oscillator to be switched on and off up to several times a second without locking up and may lead to white smoke, tears and the gnashing of teeth. To work with while I am evolving a circuit, I have ordered two of these from Amazon [www.amazon.co.uk] They are 120W which is two or three times more than a hotend needs but I will copy and modify shamelessly. More importantly they are only £5.38 each so if I fry them there will be little moaning.
Mike
Re: Induction heater May 17, 2017 03:04PM |
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newbob
............. I ordered the same induction heater board. This board has two chokes, later I saw video where presenter claims that boards with single choke with midpoint are more stable. .............
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............ Analog is a cheap way to start testing but ultimately I think digitally controlled heater would be the way to go. From what I understand, in the video in my original post, author is using micro controller for the heater, probably similarly to this doc . Using uC has it's advantages as one can vary power by changing frequency of the circuit which should be much more precise and quicker.
Re: Induction heater May 18, 2017 07:11AM |
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Re: Induction heater May 18, 2017 09:43PM |
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Re: Induction heater May 19, 2017 03:46AM |
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Re: Induction heater May 22, 2017 11:04AM |
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Re: Induction heater May 22, 2017 11:48AM |
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Re: Induction heater May 23, 2017 05:12AM |
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Re: Induction heater May 23, 2017 09:01AM |
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leadinglights
@newbob,
Thanks for the pointers to the inductance calculators, I found they gave a different value to the one that I had used. Your one was right and the inductance now comes out at 0.77microhenries - the other one (allaboutcircuits I think) said 1.92microhenries.
I have spend a bit of time browsing the web and even joined another forum [highvoltageforum.net] to get more background. The biggest worry is that the common circuits are all capable of stalling on power up - not a good thing if the is powered directly from the output of a controller as it may give several opportunities per second for the oscillator to stall and burn out.
Mike
Re: Induction heater May 23, 2017 10:25AM |
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Re: Induction heater May 25, 2017 06:14PM |
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Re: Induction heater May 25, 2017 08:59PM |
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newbob
From what I can tell hot end design have not progressed much, especially on hobby printers. I think inductive heater would increase precision, control and maybe speed of melting filament, especially for multicolor printing, but I don't see any development in this area. Here's an interesting induction heater used for FDM:
https://youtu.be/im-OYObxMdM
Re: Induction heater May 28, 2017 10:54AM |
Registered: 8 years ago Posts: 312 |
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reifsnyderb
Given that the induction heater requires more electronics, people aren't going to want to pay for it, either.