Induction Annealing??? - Page 2

Stargazer · December 6, 2009, 07:43 PM

Nice setup! I do have one question. I have never annealed a case but from what I have seen and read, aren't you supposed to dunk the cases immediately in water? Obviously that is not required if your setup is working. Just a dumb question, absolutely no flames intended. Personally I think it is a very cool application of an induction heater!

**Unclenick** · December 7, 2009, 11:22 AM

Stress relief in brass happens over a temperature range that begins at about 470°F. The charts I have show it is done at about 570°F, but most heat it to 670° to ensure surface heat has penetrated and to put the softening near a flat portion of the softening curve where the effect will be more consistent for consistent bullet pull. To anneal properly, you simply have to raise the neck and shoulder to the upper temperature without letting the case head, which must remain hard to be safe to withstand pressure, get to the lower temperature.

The old way is to set the cases in a shallow pan of water, so the water will prevent the head from heating to 470°F, for sure. The cases are then knocked over into the water as a torch flame comes off them. This ensures the heat spreads no further than it already has and makes them easier to pick up without burning your fingers.

If you heat the neck quickly enough, since the temperature decreases as the heat spreads, you don't need to worry about the head getting hot in a rifle case. In a short pistol case you would. Commercial annealing is much like the machine shown earlier. Commercial makers don't anneal pistol brass, though, since it has gone through fewer forming operations and is not as work-hardened as the neck and shoulder of a rifle case.

Yellow11,

Some U.S. companies are equipped to sell overseas and some are not. You just have to email them and ask?

gearheadpyro · December 7, 2009, 04:57 PM

Right on the money Unclenick. You've got to keep the head of the case cool and heat only the neck and shoulder. I've seen numbers a little higher than what you mentioned though, for proper annealing. I've heard you need to get the brass up to about 750-800 to anneal it quickly, and the case head must stay below 450F. If you get the case up to 950 it will start to turn orange, at this point the case is much too hot.

Many people think that the case must be immersed in water after heating to properly anneal a case. This is true with steel, you must rapidly cool it after heating to soften the metal. Brass is different though, cooling has no effect on the softening of the metal.

The primary benefit of standing the case in water is it prevents heating of the case head. It will only heat to the boiling point of water, or 212F. Unfortunately using the method that Unclenick mentioned you often only heat the neck on one side. If you do heat the whole case neck it is rarely done evenly. Uneven annealing serves to benefit little, it will cause uneven neck tensions due to different hardnesses of the brass.

A newer technique used by many is to spin the case in a propane flame using a power screwdriver or some such tool. This is a large step up from the brass in a pan method, but controlling the amount of heat delivered is still done "by eye". This results in inconsistent results at best, although with sufficient practice it is possible to do ok.

The last method which is the current best for the home reloader is a machine setup like the Ken Light machine. This automates the process, and greatly improves consistency in that lot by doing so. Lot to Lot differences will still exist though due to different flame settings and variances in the time the case is in the flame. The induction annealer I am developing will be better due to the precise delivery of heat, and precise adjustments in heater position and time heated. You will just need to mark the machine's settings with your load info and reset the machine the next time you want to anneal.

Using the induction heater to anneal very rapidly heats the brass evenly all the way around. The whole process is over in about 4 seconds, as seen in the video. The case head is warmer than I want to grab onto, but still well below the 450F mark. I currently use the induction heater with the case in a plastic tray, it shows absolutely no softening after quickly processing 50 cases.

The induction heater is the best method I know of for precise annealing, and it definitely improves accuracy. I have begun annealing the brass before every reloading, and just this morning I averaged a sub .4 moa group (5 shots each, 5 groups) with a stock remington 700 action/barrel in .308 Win (100 yards).

**Unclenick** · December 9, 2009, 06:58 PM

GHP,

Take a look at the Tempilaq supplied with the Hornady kit, and you'll be astonished how low it is. Under 475°F. I think they count on the person doing the work to overshoot the mark a bit. Either that or they screwed up, I suppose.

The following, from page 30 ofBrass.com's .PDF file, How To Make It In Brass, explains why there is any choice in the matter? for reference:

250°C=482°F
300°C=572°F
400°C=752°F
500°C=932°F

Quote:

Originally Posted by Brass.org

When cold worked brass is progressively heated, the first effect, at about 250ºC, is for the internal stresses to be relieved. This prevents stress corrosion cracking subsequently occurring and also minimises the amount of distortion which may occur during machining. This low temperature heat treatment, which should be applied for 1⁄2 to 1 hour, is known as ‘stress-relief annealing’ and has little, if any, measurable effect on the mechanical properties of the material. The improved strength due to the cold working is therefore retained.

As the temperature is increased further, a rather more fundamental change occurs at about 400ºC and above and the material starts to ‘anneal’ or soften with time at temperature. The strengthening effect of the cold working is progressively lost, until at about 500ºC the alloy is in the fully annealed condition. Restoration of the cold worked properties can then only be achieved by further cold work. Due to the volatility of the zinc at the surface of the brass, it is not easy to anneal in a batch furnace with a ‘bright’ finish solely by the use of a controlled furnace atmosphere, although strip is now commonly continuously annealed during production. When designing components which will be exposed to temperatures of 400ºC or above during manufacture (e.g. pipework with brazed or welded flanges), strength calculations must be based on the properties of the material in the annealed condition. Although cold worked material may be specified initially, it will be locally annealed during fabrication or joining operations that involve heating.

gearheadpyro · December 9, 2009, 08:33 PM

Good find Unclenick,

Further down in that article it also says that quenching can be used to prevent excessive grain growth. This is interesting because I though that brass was unaffected by quenching. I don't think it applies to something like annealing cases though as that was describing heating to 500C for 1 hour, not the "flash" annealing we are dealing with here.

The tempilaq supplied with the Hornady kit is to be applied to the body of the case, not the neck. It's to indicate that the body has gotten to hot, or is hot enough. That is why it is only 475F.

gearheadpyro · December 20, 2009, 10:38 PM

I've put together a slideshow/video with tempilaq on the cases. It shows how hot the cases get, and how localized the heat is. With the timer on the induction heater all of the cases get to the same heat.

http://www.youtube.com/watch?v=Uasv-Pyxu4g

Other than that...

The automatic induction annealer is coming along well. I've ordered many parts for it and should begin construction within a week. I decided to go to a flashed chip for controlling it, that should help keep the cost down as I won't need a whole bunch of expensive electronics for it now, just the one chip. As always, I keep the updates coming on my blog, http://www.rifles-shooting-reloading...ding-blog.html.

**Unclenick** · December 21, 2009, 03:16 PM

Loved the video. Surprised by your choice of 750-800 degrees, though. Most annealing texts I've run into have favored 350°C (662°F) as a target. I always assumed that's because, at least in a long heat, it pulls the brass to a knee in the curve (see below) where grain size and softening aren't changing with temperature quite so rapidly, making it easier to keep necks consistent? The problem with my theory there is the time factor. Since the 1 hour rest isn't present, the elevated temperature is simply accelerating events from some lower part of the curve. A time chart is needed.

P.S. Thanks for sorting out the Hornady approach. Obvious, once you told me, of course. I was accustomed to thinking in terms of Ken Howell's approach to using Tempilaq. I've stuck the crayon form in the neck/shoulder junction before, too.

Doby45 · December 21, 2009, 05:25 PM

Now you can automate the process by having the brass sit on a trap/slide door that opens to drop the annealed piece into a bucket while another piece drops in to the holder from a sorter above the annealing ring.

So It would go:

Piece drops into annealer from sorter and trigger the micro switch in the holder to cut on the annealer.

Once the annealer has done it's business it triggers the rotating trap door to drop the annealed case and return to the closed position.

Once back in the closed position the sorter would be told to drop another case.

gearheadpyro · December 21, 2009, 08:04 PM

750F to 800F is the target due to the time requirement, just like you mentioned Unclenick.

To perfectly anneal brass ~650F is the best temperature, for an hour. The problem with this for our application is the body and head would also anneal. This is very dangerous.

A lower temperature than what I chose, say 700-750 may also be used, but you want to make sure that the brass is heated all the way through. This is an issue encountered when using a propane torch much more so than the induction heater. The 750 - 800F is the compromise I came to too make sure it was heated enough, thoroughly enough, and still not overheated. The overheating starts to happen around 850F, and you'll notice in the clip of the tempilaq'd case being annealed in the last video I posted, the split instant the last bit of the 800F tempilaq melts the heater clicks off. All of the cases of a certain make and caliber heat very similarly, so by setting it up on a few cases with tempilaq I can run a whole lot the exact same.

Doby45, That's very close to what I have come up with as well, have you been looking at my notes? j/k. I hope to have a prototype put together soon to show you guys.

December 7, 2009, 11:22 AM	#27
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,743	Stress relief in brass happens over a temperature range that begins at about 470°F. The charts I have show it is done at about 570°F, but most heat it to 670° to ensure surface heat has penetrated and to put the softening near a flat portion of the softening curve where the effect will be more consistent for consistent bullet pull. To anneal properly, you simply have to raise the neck and shoulder to the upper temperature without letting the case head, which must remain hard to be safe to withstand pressure, get to the lower temperature. The old way is to set the cases in a shallow pan of water, so the water will prevent the head from heating to 470°F, for sure. The cases are then knocked over into the water as a torch flame comes off them. This ensures the heat spreads no further than it already has and makes them easier to pick up without burning your fingers. If you heat the neck quickly enough, since the temperature decreases as the heat spreads, you don't need to worry about the head getting hot in a rifle case. In a short pistol case you would. Commercial annealing is much like the machine shown earlier. Commercial makers don't anneal pistol brass, though, since it has gone through fewer forming operations and is not as work-hardened as the neck and shoulder of a rifle case. Yellow11, Some U.S. companies are equipped to sell overseas and some are not. You just have to email them and ask? __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; December 7, 2009 at 11:41 AM.

December 21, 2009, 03:16 PM	#32
Unclenick Staff Join Date: March 4, 2005 Location: Ohio Posts: 21,743	Loved the video. Surprised by your choice of 750-800 degrees, though. Most annealing texts I've run into have favored 350°C (662°F) as a target. I always assumed that's because, at least in a long heat, it pulls the brass to a knee in the curve (see below) where grain size and softening aren't changing with temperature quite so rapidly, making it easier to keep necks consistent? The problem with my theory there is the time factor. Since the 1 hour rest isn't present, the elevated temperature is simply accelerating events from some lower part of the curve. A time chart is needed. P.S. Thanks for sorting out the Hornady approach. Obvious, once you told me, of course. I was accustomed to thinking in terms of Ken Howell's approach to using Tempilaq. I've stuck the crayon form in the neck/shoulder junction before, too. __________________ Gunsite Orange Hat Family Member CMP Certified GSM Master Instructor NRA Certified Rifle Instructor NRA Benefactor Member and Golden Eagle Last edited by Unclenick; December 21, 2009 at 05:46 PM.

December 6, 2009, 07:43 PM	#26
Stargazer Senior Member Join Date: August 6, 2006 Location: Republic of Texas Posts: 506	Nice setup! I do have one question. I have never annealed a case but from what I have seen and read, aren't you supposed to dunk the cases immediately in water? Obviously that is not required if your setup is working. Just a dumb question, absolutely no flames intended. Personally I think it is a very cool application of an induction heater!

December 7, 2009, 04:57 PM	#28
gearheadpyro Senior Member Join Date: September 3, 2009 Location: Charleston, SC Posts: 169	Right on the money Unclenick. You've got to keep the head of the case cool and heat only the neck and shoulder. I've seen numbers a little higher than what you mentioned though, for proper annealing. I've heard you need to get the brass up to about 750-800 to anneal it quickly, and the case head must stay below 450F. If you get the case up to 950 it will start to turn orange, at this point the case is much too hot. Many people think that the case must be immersed in water after heating to properly anneal a case. This is true with steel, you must rapidly cool it after heating to soften the metal. Brass is different though, cooling has no effect on the softening of the metal. The primary benefit of standing the case in water is it prevents heating of the case head. It will only heat to the boiling point of water, or 212F. Unfortunately using the method that Unclenick mentioned you often only heat the neck on one side. If you do heat the whole case neck it is rarely done evenly. Uneven annealing serves to benefit little, it will cause uneven neck tensions due to different hardnesses of the brass. A newer technique used by many is to spin the case in a propane flame using a power screwdriver or some such tool. This is a large step up from the brass in a pan method, but controlling the amount of heat delivered is still done "by eye". This results in inconsistent results at best, although with sufficient practice it is possible to do ok. The last method which is the current best for the home reloader is a machine setup like the Ken Light machine. This automates the process, and greatly improves consistency in that lot by doing so. Lot to Lot differences will still exist though due to different flame settings and variances in the time the case is in the flame. The induction annealer I am developing will be better due to the precise delivery of heat, and precise adjustments in heater position and time heated. You will just need to mark the machine's settings with your load info and reset the machine the next time you want to anneal. Using the induction heater to anneal very rapidly heats the brass evenly all the way around. The whole process is over in about 4 seconds, as seen in the video. The case head is warmer than I want to grab onto, but still well below the 450F mark. I currently use the induction heater with the case in a plastic tray, it shows absolutely no softening after quickly processing 50 cases. The induction heater is the best method I know of for precise annealing, and it definitely improves accuracy. I have begun annealing the brass before every reloading, and just this morning I averaged a sub .4 moa group (5 shots each, 5 groups) with a stock remington 700 action/barrel in .308 Win (100 yards).

December 9, 2009, 08:33 PM	#30
gearheadpyro Senior Member Join Date: September 3, 2009 Location: Charleston, SC Posts: 169	Good find Unclenick, Further down in that article it also says that quenching can be used to prevent excessive grain growth. This is interesting because I though that brass was unaffected by quenching. I don't think it applies to something like annealing cases though as that was describing heating to 500C for 1 hour, not the "flash" annealing we are dealing with here. The tempilaq supplied with the Hornady kit is to be applied to the body of the case, not the neck. It's to indicate that the body has gotten to hot, or is hot enough. That is why it is only 475F.

December 20, 2009, 10:38 PM	#31
gearheadpyro Senior Member Join Date: September 3, 2009 Location: Charleston, SC Posts: 169	I've put together a slideshow/video with tempilaq on the cases. It shows how hot the cases get, and how localized the heat is. With the timer on the induction heater all of the cases get to the same heat. http://www.youtube.com/watch?v=Uasv-Pyxu4g Other than that... The automatic induction annealer is coming along well. I've ordered many parts for it and should begin construction within a week. I decided to go to a flashed chip for controlling it, that should help keep the cost down as I won't need a whole bunch of expensive electronics for it now, just the one chip. As always, I keep the updates coming on my blog, http://www.rifles-shooting-reloading...ding-blog.html.

December 21, 2009, 05:25 PM	#33
Doby45 Senior Member Join Date: January 19, 2009 Location: Powder Springs, GA Posts: 213	Now you can automate the process by having the brass sit on a trap/slide door that opens to drop the annealed piece into a bucket while another piece drops in to the holder from a sorter above the annealing ring. So It would go: Piece drops into annealer from sorter and trigger the micro switch in the holder to cut on the annealer. Once the annealer has done it's business it triggers the rotating trap door to drop the annealed case and return to the closed position. Once back in the closed position the sorter would be told to drop another case.

December 21, 2009, 08:04 PM	#34
gearheadpyro Senior Member Join Date: September 3, 2009 Location: Charleston, SC Posts: 169	750F to 800F is the target due to the time requirement, just like you mentioned Unclenick. To perfectly anneal brass ~650F is the best temperature, for an hour. The problem with this for our application is the body and head would also anneal. This is very dangerous. A lower temperature than what I chose, say 700-750 may also be used, but you want to make sure that the brass is heated all the way through. This is an issue encountered when using a propane torch much more so than the induction heater. The 750 - 800F is the compromise I came to too make sure it was heated enough, thoroughly enough, and still not overheated. The overheating starts to happen around 850F, and you'll notice in the clip of the tempilaq'd case being annealed in the last video I posted, the split instant the last bit of the 800F tempilaq melts the heater clicks off. All of the cases of a certain make and caliber heat very similarly, so by setting it up on a few cases with tempilaq I can run a whole lot the exact same. Doby45, That's very close to what I have come up with as well, have you been looking at my notes? j/k. I hope to have a prototype put together soon to show you guys.