My name is Andrew Poe, I am the owner of the website linked to in the first few posts on this thread (thanks Heavies!). I used to be an active member on this forum (see number of posts), but haven't posted anything in a while. I've had a lot of other things going on...
I've been working on an automated induction annealing machine on and off for about a year (maybe a little more) now, and I am almost done with it. My work on an automated machine has been hampered mainly by the cost (I'm forced to develop this on a limited budget), but thanks to several innovations and ideas from many people the cost has come way down.
I originally started off with the mini-ductor as my induction heater, but have since moved to using a Roy 2.2 from Fluxeon Inc. Fluxeon's website is http://www.fluxeon.com/
in case you want to check them out. The new heater is more powerful, the cost is substantially less than even the best deal on a mini-ductor, and the guys are great to work with. If your interested in trying your hand at induction heating I would advise using Fluxeon's Roy 2.2. The way the heater works is different from the mini-ductor, but it is better suited for annealing brass.
The advantages of using an induction heater to anneal instead of propane are numerous. The cases always heat to the exact same temperature, it's extremely quick and easy to set up, no worries about open flames or propane (the case is the only part that gets significantly hot), I could go on and on. The downsides are (up until recently) high cost, and induction heating is a little bit tricky to get right (hence the reason I've been working on this machine).
The biggest tricks to using induction heat for annealing are getting the setup right, and controlling the heater. Work coils vary in their effectiveness; diameter of the work coil in relation to the case, number of turns and layers in the work coil, etc, all have an impact on the heaters output, as does what you are heating. Brass is a difficult metal to heat using this method because it is a very good conductor of electricity. Once you get the setup right though, the cases will heat very quickly. The difference between a perfect anneal and way overdone is typically less than 1/2 second.
My machine is all microprocessor controlled and eliminates most of these problems. It operates in much the same way as the current propane annealers available, only with a very different heat source. The cases are loaded into a turntable, the machine rotates them into the flux concentrator (which takes the place of the work coil), then anneals the case. Time is controllable anywhere from 0.025 seconds up to 9.975 seconds, most cases take around 3 seconds to heat to the correct anneal temp of 700 degrees. I've got a LCD display screen on the machine to tell me what the machine is doing and the amount of time that the heater is set for.
All that is required to run my machine is three simple steps:
Set the height of the flux concentrator,
Set the time the heater needs to run (can be a time recorded from previous runs since heat output is always consistent, or set a new time using test mode),
Press start, then load cases as the machine anneals them.
The way I have the machine set up now it has three modes of operation:
1- Test mode. This mode allows you to run a test on 1 case. It is only used for setting up the amount of time to anneal the case.
2- Automatic mode. This is the "normal operation" mode. The operator loads the cases, and the machine anneals them. Total time per case varies depending on how long the heater is set for, but I tend to average about 5 seconds total per case. I usually anneal lots of 100 cases at a time and it takes me about 10-12 minutes (including setup).
3- Manual mode. This mode is handy for doing things that don't allow for the work piece to be moved by the turntable (like annealing bullets or bonding lead cores to jackets for those that make their own bullets). In this mode I have to press a button every time the heater needs to be run, then I have to manually move that object out and the next one in.
I'm trying to get the final prototype housing completed this weekend, and I've got the last of the electronics coming in next week. Hopefully my prototype should be 100% done within 2 weeks. When it is done and I'm (mostly) satisfied with it I'll post pictures and a video of it in action here and on my own site.
I hope this post helps answer some questions about induction annealing in general and my machine as I see in my absence here I've gotten several PM's about it.