View Full Version : Induction Heating to anneal cases

08-27-2008, 07:11 PM
Iíve been looking at Induction Heating to anneal cases. It seems that the temperature could be controlled exactly. This could probably be used for annealing cases. Below is an example.


Any opinions welcome.

chuck furniss
08-27-2008, 09:48 PM
Only if you can control how far down the case the heat will go.
Brass will discolor at the annealed area and this color must not extend below the sholder,also you will have to control the temp.
It is best to anneal with the base sitting in water to prevent annealing the lower 3/4 of the case.
If it was me I would forget it.


Jay, Idaho
08-27-2008, 10:53 PM
I've used a small induction heater to heat treat punches, gravers, draw back ejector and perforator pin heads. I'd love to try one for case annealing but where do you get one and how expensive are they?
The unit that I used had a timer (darkroom timer) and you could vary the power of the unit. It would be very easy to get it set up to have consistent results at case annealing. I would usually adjust the power so that I had a tme of about 7 to 10 seconds turned on.
There was water running through the tubing. I never forgot to turn on the water but others did.

08-27-2008, 11:19 PM
I e-mailed the company listed above about this and will post the results.

My hobby is target shooting. I reload my cartridges and my question is in regards to the brass cases I reload. When firing and resizing my cartridges the brass becomes work hardened, which some reloaders try to anneal to extend the brass life. The methods used by most reloaders seem crude and involve some guess work. I ran across your site and wonder if induction heating to partially anneal the case neck (bring it back to it's original softness) would be possible? Only the neck and part of the shoulder of the case would need to be annealed. The lower ĺ of the case has to remain as from the factory (not annealed) to remain strong enough to take the pressures involved when shot. Some reloaders set their cases in water to make sure the lower ĺ of the case doesnít get heated when they try to anneal using a torch. If the induction heating process could be used for case annealing there would probably be a lot of reloaders interested, if the price of the equipment to do this was not prohibitive. Does this sound like something that would work and what would the equipment to do this cost?

If you have any question about the above I'll try to answer it.

Thank You

Here is a video of a tube -


And some others -


08-29-2008, 10:48 AM
I received a reply from Ameritherm, Inc.,

Induction is a prefect fit for brass annealing. The smallest unit we have available at this point is a 1 kilowatt, our HOTSHOT-1. It sells for about $5,000.00.
We are working on a unit that will sell in the $1,000.00 range, but it is not available at this time.

A little to expensive for me, but If a unit could be made for less $$$ I think that Induction Heating to anneal cases would be the way to go.
Except someone in another forum said on the Induction Heater they used it had a Warning that said - Use of this equipment "May Cause Bone Cancer". This doesnít sound to good.

brian roberts
08-29-2008, 07:30 PM
One of the foremost considerations when reloading is:Stress Corrosion Cracking, which is caused by the formation of Ammonia in the case as a result of the firing process. One can tumble clean the cases w/a tablespoon or so(depending on the size of your tumbler)of Ascorbic Acid(powdered Vitamin C) I'm still experimenting w/this, as it leaves the brass a subdued color I'm not accustomed to. Perhaps a salt of some sort would be better, or even a bath in which Ascorbic Acid was one of the ingredients. Of course, the bath would have to be brief, & the rinse complete. Most handloaders(I'm guilty, too!) believe that when necks begin cracking, the solution is to re-anneal.....but annealing will not cure the problem of corrosion cracking, & most brass that's been carefully cleaned is just thrown away, before its time. It would be nice if someone w/more of a chemistry background could point us in a better direction....

John Kielly
08-29-2008, 07:56 PM
Throwing away has always sounded good to me.

I trust the manufacturers to mix gunpowders suitable for my needs & cases with the necessary physical characteristics. I've never fancied myself a chemist capable of making or mixing powders or an engineer with the skill to modify workhardened brass with any guarantee of consistency.

08-30-2008, 08:37 AM
I was chatting to a retired Palma shooter at the last club shoot I attended.
Among other things annealing brass was in the discussion.

I could be wrong but I think this is exactly the method he uses on his brass.
He told me he picked up a machine from a company that was going out of business. Said this machine would cost well into five figures purchased new but he got it on the cheap.

If I got it right his particular machine has sensors which automatically shut it down at a certain temp of his choosing.

Its hard to have an intelligent conversation with muffs on and ten guns blasting away. Even harder when I'm involved in it.

Louis Boyd
08-30-2008, 09:48 AM
There are other devices which could heat brass to anealing temperatures without flame which are a lot less expensive than an induction heater. One would be a focused xenon arc lamp, or even cheaper, a fucused 500 or 1000 watt incadescent lamp. No, I haven't tried it.

This site shows the mechanical and termal properties of C260 brass (aka cartridge brass). Most cartridges are similar though not necessarily this exact alloy.

http://www.matweb.com/search/datasheet.aspx?matguid=bb5d603582d64195bec5fd8d372 42183&ckck=1

It gives the anealing temperature range as 425 to 750 Centigrade.

08-31-2008, 10:25 AM
I asked about induction heating on another forum and got this interesting reply -

One problem that folks do not realize is that brass hardness within a lot# may vary as much as 13% in rockwell hardness due to mixture of the alloy. This inconsistant Rockwell hardness gets blamed in a lot of different areas (other than the real cause) and annealing is one of them.

I had an engineering firm Rockwell test cases. The results were so depressing, I can't find the positive in it.

PMC brass made in Korea was much harder and consistant than Rem, Win, and Fed & Weatherby was real soft. OF course, there could only be one Lot# of brass tested, Lot # to lot # could also be a whole can of worms.

It would be very interesting to see an engineer that had unlimited access to Rockwell testing do an extensive test on brass. No doubt that this test would indeed shock us all with the little sampling that I had done.