Annealing with Induction Heater?
- Thread starter Paul70
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4runnerman
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Uneven heating with one torch: you have apparently discovered a phenomenon that has eluded reloaders for 100 years! Just angle the torch flame downward so that it covers the entire case mouth.
Bill- Just full of questions here- I have tried that also And while in thought it might look like it works, In reality it does not. What ever side you have the torch on, That side is going to get hotter faster than the other. It will heat the other side-True, But not as fast and not even. Coming from a angel is better,but still does not work that great. That is why I use 2 torches. Even heating all around. All high grade Annealing Machines I have seen rotate the brass for even heating. I could get away with one torch, but I would still want to rotate the brass.
Bill- Just full of questions here- I have tried that also And while in thought it might look like it works, In reality it does not. What ever side you have the torch on, That side is going to get hotter faster than the other. It will heat the other side-True, But not as fast and not even. Coming from a angel is better,but still does not work that great. That is why I use 2 torches. Even heating all around. All high grade Annealing Machines I have seen rotate the brass for even heating. I could get away with one torch, but I would still want to rotate the brass.
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Greetings. A friend pointed me to this thread. I shoot metallic silhouette with a custom built .308 bolt handgun. I'm also the Chief Engineer of Fluxeon.com, a company that manufacturer induction heaters. We offer a heater specifically for annealing brass called the Annie. The induction heater used in the Annie is Open Source here so if anyone wants to roll their own, they can.
Perhaps I can answer some questions that have arisen in this thread.
Induction heating is vastly superior to flame annealing in repeatability and speed. I designed the Annie to heat a .30 cal case in 1.5 seconds. A .50BMG takes approximately 12 seconds. That is long enough for the built-in timer perform a highly repeatable heat cycle.
The heating stops at the edge of the magnetic flux (essentially the edge of the ferrite flux concentrator). Since the heating occurs so rapidly, the heat does not spread outside the desired zone.
I neck-size only with my .308 ammo. So I inserted a wad of Frax (heat-proof alumina felt) into the flux concentrator so that when a case is inserted and is touching the Frax stop, only the neck is in the magnetic gap. The cycle time is about 0.8 seconds and the heat stops where the neck meets the shoulder.
I have found that quenching has absolutely no effect on accuracy which is what we're interested in.
The design of the work coil/flux concentrator of the Annie is such that it can easily be retrofitted to flame-based automatic annealing machine. Giraud Machine is about to introduce an induction version of their automatic annealer. You can see it in action here.
Someone asked how the heat is confined to a specific area. That is the job of the ferrite flux concentrator. The photos on the Fluxeon site show a slotted toroid. We've now gone to a two piece rectangular concentrator so that the gap can be adjusted for the particular case. We supply pieces to go from .223 and below to .50BMG.
Other than speed and reproducibility, the other major advantage of induction heating is that there is no flame around the reloading bench. Only the case neck itself gets hot so there is practically no risk of fire or the ignition of powder. I have mine sitting on my bench just a few feet away from my press. Far enough away that there won't be any tramp powder laying around but close enough that I can roll my stool over to start an annealing run.
I'm not going to even dip a toe into the temperature argument. I'll just say that I use 750 deg F and that has worked fine for many years.
If you have any more questions about induction annealing, feel free to ask.
John
Perhaps I can answer some questions that have arisen in this thread.
Induction heating is vastly superior to flame annealing in repeatability and speed. I designed the Annie to heat a .30 cal case in 1.5 seconds. A .50BMG takes approximately 12 seconds. That is long enough for the built-in timer perform a highly repeatable heat cycle.
The heating stops at the edge of the magnetic flux (essentially the edge of the ferrite flux concentrator). Since the heating occurs so rapidly, the heat does not spread outside the desired zone.
I neck-size only with my .308 ammo. So I inserted a wad of Frax (heat-proof alumina felt) into the flux concentrator so that when a case is inserted and is touching the Frax stop, only the neck is in the magnetic gap. The cycle time is about 0.8 seconds and the heat stops where the neck meets the shoulder.
I have found that quenching has absolutely no effect on accuracy which is what we're interested in.
The design of the work coil/flux concentrator of the Annie is such that it can easily be retrofitted to flame-based automatic annealing machine. Giraud Machine is about to introduce an induction version of their automatic annealer. You can see it in action here.
Someone asked how the heat is confined to a specific area. That is the job of the ferrite flux concentrator. The photos on the Fluxeon site show a slotted toroid. We've now gone to a two piece rectangular concentrator so that the gap can be adjusted for the particular case. We supply pieces to go from .223 and below to .50BMG.
Other than speed and reproducibility, the other major advantage of induction heating is that there is no flame around the reloading bench. Only the case neck itself gets hot so there is practically no risk of fire or the ignition of powder. I have mine sitting on my bench just a few feet away from my press. Far enough away that there won't be any tramp powder laying around but close enough that I can roll my stool over to start an annealing run.
I'm not going to even dip a toe into the temperature argument. I'll just say that I use 750 deg F and that has worked fine for many years.
If you have any more questions about induction annealing, feel free to ask.
John
4runnerman
New member
Now I got to get me one of those babys.
That's where the rules come in . If you follow the proper rules . They will cover the fundamentals . What's the problem ? It seems simple , there are rules . Do not color outside the rules and you will be in keeping with the rules .
I thought you liked rules ? It's like playing in traffic , stick to the rules and you will survive . This seems pretty straight forward to me . Stick to the rules and you will be fine .
Bill DeShivs said:
Bill,
Mete gave the answer. What happens in full annealing (dead soft brass) is grain growth has occurred that compromises the tensile strength of the brass. You'll notice that a lot of folks can get a dozen or even twenty reloads out of a new case, but then say they have to anneal every third or fourth time they reload or the necks start to crack. That's because they overdid the annealing as compared to what the factory does, or they'd be getting factory levels of reloadings before case necks started to split.
Strictly speaking, case necks don't need to be annealed. They only need to be stress-relieved to eliminate work hardening. That requires a lower temperature that doesn't reduce tensile strength appreciably. The term of art used for stress relieving brass is "partial annealing". I don't know why they came up with that rather than just calling it "stress-relieving", but information at copper.org or one of the other industry association sites I found some time back said that's what they use.
Below is a plot for one hour temperature exposure time. It makes the difference between stress and full annealing more clear. With the shorter annealing times used with cases, you have to get the temperature higher to get the same result, but the general consensus I've found is that by the time a torch makes the cases visibly red in color, you've blown past the stress relieving level. 650°F indicators usually work on a neck. They assume you will overshoot and actually get to 700-750°F by the time you see and react to the temperature indicator change. A 450°-475° indicator can be used below the shoulder, like Hornady's kit does, on the assumption it shows you when you want heat to stop traveling down the case.
