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 Post subject: Re: Induction Annealing
PostPosted: Sun May 06, 2012 8:02 pm 
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Notar wrote:
Cool sim, can you run one with flame, and a 5-6 sec duration for comparison. 500 W, holy shizz, maybe flame will last a long time for case annealing.


I can in a bit, sure.


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 Post subject: Re: Induction Annealing
PostPosted: Tue May 08, 2012 5:47 pm 
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Joined: Tue May 08, 2012 4:57 pm
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Hi folks,

I picked up this thread through a Google Alert. Aside from shooting (metallic silhouette), my other hobby as well as my profession is designing and working with induction heaters. I thought that I could help out on brass annealing, as my company (http://www.fluxeon.com) has designed case annealers for several customers.

Of particular interest may be my open source Royer type induction heater:

http://www.neon-john.net/Induction/Roy/Roy.htm

This is a very simple heater and will anneal a .308 brass in about a second. Fluxeon offers "hard to find" parts kits for this heater as well as assembled and tested boards.

Better than a circular work coil for annealing is the "flux concentrator".

http://www.neon-john.com/Induction/Roy/ ... trator.htm

This uses a ferrite core material to concentrate and conduct the magnetic flux to a place where it is desired. In this case, to a nice gap into which the brass can be inserted.

My friend Andrew Poe over at Southern Marksman has made an automatic annealing machine that uses my induction unit. Here is his page on induction heating.

http://www.southernmarksman.com/inducti ... ling.shtml

Here's his machine in action:

http://www.southernmarksman.com/inducti ... se-5.shtml

Feel free to ask any questions regarding induction annealing or heating in general.

John DeArmond
jgd@fluxeon.com


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 Post subject: Re: Induction Annealing
PostPosted: Tue May 08, 2012 9:03 pm 
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Joined: Sun Apr 01, 2012 10:59 pm
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neonjohn wrote:
Hi folks,

I picked up this thread through a Google Alert. Aside from shooting (metallic silhouette), my other hobby as well as my profession is designing and working with induction heaters. I thought that I could help out on brass annealing, as my company (http://www.fluxeon.com) has designed case annealers for several customers.

Of particular interest may be my open source Royer type induction heater:

http://www.neon-john.net/Induction/Roy/Roy.htm

This is a very simple heater and will anneal a .308 brass in about a second. Fluxeon offers "hard to find" parts kits for this heater as well as assembled and tested boards.

Better than a circular work coil for annealing is the "flux concentrator".

http://www.neon-john.com/Induction/Roy/ ... trator.htm

This uses a ferrite core material to concentrate and conduct the magnetic flux to a place where it is desired. In this case, to a nice gap into which the brass can be inserted.

My friend Andrew Poe over at Southern Marksman has made an automatic annealing machine that uses my induction unit. Here is his page on induction heating.

http://www.southernmarksman.com/inducti ... ling.shtml

Here's his machine in action:

http://www.southernmarksman.com/inducti ... se-5.shtml

Feel free to ask any questions regarding induction annealing or heating in general.

John DeArmond
jgd@fluxeon.com


Any possibility of using closed-loop feedback from an IR sensor to control temperature through your board? I'm working on a system that does this with a flame right now, but an all-electric solution might be neat too.


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 Post subject: Re: Induction Annealing
PostPosted: Tue May 08, 2012 9:57 pm 
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RocketmanOU wrote:
neonjohn wrote:
Hi folks,
Any possibility of using closed-loop feedback from an IR sensor to control temperature through your board? I'm working on a system that does this with a flame right now, but an all-electric solution might be neat too.


Andrew and I have worked on that a bit. The most obvious solution, an optical pyrometer, won't work because brass has such a low thermal emissivity constant (0.04 for unoxidized brass) and it varies so widely with surface finish (in the 0.40 to 0.60, depending on surface finish and type of contamination. If you always used brass fresh out of the tumbler then perhaps optical could be made to work.

Another thing that we've looked is a thermocouple spring-loaded against the case mouth. There are two problems, one easily managed and one not so much. The easily managed one is that RF from the heater tends to get back into the T/C controller. I pretty much stopped that by wrapping the lead wire a few turns around a ferrite toroid that I had handy.

The other problem that at least one of the wires in the most common types of thermocouples is magnetic. That means that it absorbs induction heat and does so better than the non-magnetic brass. A partial solution is to use T/C wire fine enough that it doesn't appreciably absorb energy. The downside is that this extremely fine and fragile wire is not durable.

We've both pretty much decided that a purely time-based system is good enough. Andrew has spent a lot of time with the Templaq verifying this. Unlike with flame heating, the induction heat is on and off instantly and so can be controlled very precisely. The only compensation that would be needed would be for changes in line voltage. A variac is a simple solution to that problem. Andrew is using an Arudino as the controller so line compensation can be easily added, if he isn't already doing it.

John DeArmond
jgd@fluxeon.com


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 Post subject: Re: Induction Annealing
PostPosted: Wed May 09, 2012 8:25 am 
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Joined: Sun Apr 01, 2012 10:59 pm
Posts: 16
neonjohn wrote:
RocketmanOU wrote:
neonjohn wrote:
Hi folks,
Any possibility of using closed-loop feedback from an IR sensor to control temperature through your board? I'm working on a system that does this with a flame right now, but an all-electric solution might be neat too.


Andrew and I have worked on that a bit. The most obvious solution, an optical pyrometer, won't work because brass has such a low thermal emissivity constant (0.04 for unoxidized brass) and it varies so widely with surface finish (in the 0.40 to 0.60, depending on surface finish and type of contamination. If you always used brass fresh out of the tumbler then perhaps optical could be made to work.

Another thing that we've looked is a thermocouple spring-loaded against the case mouth. There are two problems, one easily managed and one not so much. The easily managed one is that RF from the heater tends to get back into the T/C controller. I pretty much stopped that by wrapping the lead wire a few turns around a ferrite toroid that I had handy.

The other problem that at least one of the wires in the most common types of thermocouples is magnetic. That means that it absorbs induction heat and does so better than the non-magnetic brass. A partial solution is to use T/C wire fine enough that it doesn't appreciably absorb energy. The downside is that this extremely fine and fragile wire is not durable.

We've both pretty much decided that a purely time-based system is good enough. Andrew has spent a lot of time with the Templaq verifying this. Unlike with flame heating, the induction heat is on and off instantly and so can be controlled very precisely. The only compensation that would be needed would be for changes in line voltage. A variac is a simple solution to that problem. Andrew is using an Arudino as the controller so line compensation can be easily added, if he isn't already doing it.

John DeArmond
jgd@fluxeon.com



Very interesting! Let me know if you need any finite element work done to look at temperature distributions (since tempilaq only gives you one point).


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