APOD Firearms

Annealing brass cases, Quenching

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  • FrommerStop

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    Annealing brass cases, Quenching is said by many to not be needed.

    I have been doing some reading. All agree that the base and lower body of the cases must not be heated. Now I am reading that quenching is not needed. It seems the longer the brass cases is at a high temperature, the longer the time period that the brass has to soften. It seems rotating the cases or rotating the flame about the case is the way to go and I thinking this all over. Due to ammo cost I may be reforming base to other calibers to make things like 300 blackout and 8x57 mauser and maybe others.

    Many like to have the base of the annealed case sitting in water to make sure it does not get heated to softness.

    Many like to rotate the case for a fix period of time under a flame. I am thinking of all sorts of things at the moment. I have some record turn tables for example that I was about to toss in the trash. Could a cake pan like the one below be used. Place it upside down on the turn table and put a case on the pedestal, heat it for so many timed turns and with a tool knock if off and put a new one up. Red arrow would indicate location of the turned cases.

    InkedWilton-cake-pans_pnpr0c_LI.jpg
    Others use a lower speed turning drill with a piece of welding rod to turn the neck which is also heated.

    Annealed case

    annealed.jpg
     

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    reel_crazy

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    looks like it might work.. you definitely need to have a way to limit heating of the body... old turntable would give you a repeatable speed of rotation i wonder if an infrared thermometer would work to determine the temperature... heck ya might be able to listen to an old elvis 45 at the same time.. another option seems to be induction heating.. no need to spin the case , no flames... and perhaps infrared temp sensing might work there as well...

    rich
     

    FrommerStop

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    Relative to temperature, you want it to be uniform for each case. So using the same exposure time, torch flame same adjustment, distance etc. The annealing treatment needs to be the same if one wants consistent neck tension on the seated bullets.
     

    reel_crazy

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    for consistency the whole process screams cnc... you want precise, repeatable control of an essentially linear movement process ... applying a heat source along an axis, cooling etc... cooling could easily be done...i.e. either flushing coolant, cleaning solution, air through the primer pocket opening or even using a combination of air/liquid..as coolant control is a basic part of cnc.. if you are able to somewhat precisely measure the actual skin temp you could then look at how changes in the heat is applied ... mouth to towards shoulder/case, shoulder/case towards mouth effect overall consistency etc...

    rich
     

    FrommerStop

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    for consistency the whole process screams cnc... you want precise, repeatable control of an essentially linear movement process ... applying a heat source along an axis, cooling etc... cooling could easily be done...i.e. either flushing coolant, cleaning solution, air through the primer pocket opening or even using a combination of air/liquid..as coolant control is a basic part of cnc.. if you are able to somewhat precisely measure the actual skin temp you could then look at how changes in the heat is applied ... mouth to towards shoulder/case, shoulder/case towards mouth effect overall consistency etc...

    rich
    LOL, be cheaper to buy brand new cases then to invest in computer controlled technology. There is such available for a goodly number of dollars. For a small time reloader, one can just careful and precise as to how one does things and get a reasonably good result.
     

    Jhunter

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    Yes I have one. It’s great for a weekend shooter, but It would not be my option to tackle 5000 cases at a time. The AMP Annealer is the best thing on the market at the moment. You can actually hold the base of the brass after the neck has been annealed. You must allow the cases to cool before handling after using the annealeez
     

    Jester896

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    those type of annealers can be made very inexpensivly
    https://www.youtube.com/watch?v=k0xE-6bSwME
    my buddy made one similar to this. there were only one issue I found when using it. The angle on the brass hopper could have been different...it only allows to to put in 50 or so cases at a time. A little Tempilaq and your good to go for set up. I kinda feel like it needs quench if fire is involved.
     

    FrommerStop

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    looks like a fair investment in time to make, but it is interesting and might be something I might want to make when I have a bit of time.
     

    Jester896

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    It would be for me too. His schedule is different than mine. Sure does work good, as well as the Ken Light my other buddy lets me use. That one is even hooked to a Dillon case feeder. You can always spin them in a deep well socket on a drill and drop them in a bucket of water. All depends on you need really.
     

    Snake-Eyes

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    The Ken Light "BC-1000" is now handled by the designer, Brian Crawford, since Mr. Light passed away.
    He wrote a really informative article on the specifics of annealling. Good read. Answers the "to quench, or not to quench" question. A very small portion (maybe a few sentences?) of the article is annealer-specific to the BC-1000, but the vast majority is universal info.

    http://www.lasc.us/CartridgeCaseAnnealing.htm
     

    FrommerStop

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    Thanks there are a lot of other good articles on that site

    Additional Authors And Articles

    Dual PID Temperature Controller The Myth of Arsenic Cartridge Case Annealing
    By: Keith G. Benedict By: Wiljen By: Ken Light
    pdf version pdf version pdf version
    A Nation Of Cowards 22 Rimfire Specialty Ammo Marlin Leverguns
    By: Jeffrey R. Snyder By: PACO By: PACO
    pdf version pdf version pdf version
    African Hunt With Cast Bullets Looking Back - The 22 Rimfire The Masters And Its Guns
    By: Sarel Badenhorst By: PACO By: Larry Stuhlman
    pdf version pdf version pdf version

    and much more.
     

    FrommerStop

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    He speaks of judging the shine of the case and I will have to review that. While quenching is not needed, I can see if it is a home made set up there is a safety factor if the base is immersed in water while heating. No matter what mistakes one might make, it will prevent the case head from becoming too soft.
     

    Jester896

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    I think you are right on home quenching. It is a good read and good info. I also believe that it is geared for his product. I wouldn't find it necessary to quench when using his annealer and don't. The heavy aluminum acts as a heat sink (the older one is heavier) and also keep the center of the disk full of water to help. It doesn't contact the brass it cools the heat sink.
     

    reel_crazy

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    Thought I would share some info I have managed to find about the properties of cartridge brass, for folks trying to wade thru all the info/miss-info on the web….

    One of the most informative documents I have found is a report published by the CDA Copper Development Assoc. You can duckduckgo/ google it and get a couple links to it, like here
    http://www.nationalbronze.com/pub-117---the-brasses_whole_web-pdf.pdf

    It is a pdf doc, with lots of info about brass and its properties.

    As most of us know cartridge brass is an alloy of copper/zinc. The proportions are 70% Cu 30% Zn.
    It is an “alpha” or single phase alloy.

    When the alloy contains less than about 35% Zn, the zinc stays
    in solid solution in the copper. Such brasses are known as single
    phase, or alpha brasses. They have good ductility at ambient
    temperatures and are ideal for cold working. When more zinc
    is added, a second phase, beta, is formed, and at room
    temperature the alloy is a mixture of the two phases. These
    brasses are known as two-phase, alpha/beta, or duplex brasses.

    Annealing
    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.
    Annealing (full)
    In order to fully soften most brasses, heat to 500-550oC for 1⁄2 to
    1 hour at temperature, then either air cool or, especially for alpha
    alloys, ensure that excessive grain growth is prevented by a
    quench or rapid furnace cool. ‘Flash’ annealing can be carried out
    at higher temperatures for considerably shorter times, but care is
    needed to avoid excessive grain growth.
    The use of a protective atmosphere reduces oxidation. Normally
    this can be prepared from cracked or partly burnt ammonia to
    give an atmosphere high in nitrogen and water vapour. Since zinc
    is volatile, care needs to be taken to avoid overheating.
    Stress relieving
    In order to relieve internal stresses without loss of properties a
    low-temperature anneal such as 1⁄2 to 1 hour at 250-300oC should
    be used, dependent on section size.



    For the folks like me who hate SI units
    250C 482F
    400C 752F
    500C 932F
    550C 1022F
    250-300C 482-572F

    Takeaways

    It appears that some sort of quenching is desirable when “flash annealing” i.e. what we are talking about here, although not sure how one would quantify or determine if excessive grain growth has occurred without microscopic analysis. Anyways it is easily accomplished with a blast of air or a dunk in water.
    What I find most interesting is the stress relieving step. I do not know if any reloaders, manufactures etc. do this as a final step in the process. It is certainly very simple as it can be done on a batch basis, unlike the flash annealing process which is dealing with one cartridge at a time.


    Cleaning
    Surface cleaning techniques
    Before any finish can be applied, it is normal to clean the surface
    thoroughly in order to ensure good results.
    Chemical pre-treatment in alkaline solutions
    For the cleaning of copper and copper-alloy material, solutions are
    based on compounds such as trisodium phosphate, sodium
    metasilicate, sodium hydroxide and sodium carbonate, together with
    a blend of surfactants, wetting agents and emulsifiers. Generally the
    cleaning solution contains 2-5% of the salts. An efficient alkaline
    cleaner must also protect the surface from etching and staining, and
    must not cause any colour change of the surface. Cleaners containing
    complexants may allow simultaneous removal of the surface grease
    contamination and surface oxidation from copper and brass.
    Degreasing in organic solvents
    Many organic solvents dissolve oils and fats from metallic
    surfaces, but they do not always remove the tightly adherent dirt
    particles nor inorganic products such as polishing compound
    residues. For this purpose the cleaning process can be
    accelerated by the use of ultrasonic agitation.
    All organic solvents must, of course, be used only in cleaning
    plant which prevents the release of the solvent or its vapour into
    the workplace or the surrounding air space. This requirement has
    led to the development of water-based cleaners and degreasers,
    which can be used without elaborate precautions or in fully
    automated plants.
    Pickling
    Oxides formed during heat treatment of most brasses can be
    removed by immersing the products in a 10% sulphuric acid
    mixture, followed by water rinsing.


    The only admonition here would be to avoid any cleaners containing ammonia.

    Notes to Table 24
    All copper alloys are rapidly attacked by ammonia in moist conditions,
    with the formation of a bright blue corrosion product, and contact should
    therefore obviously be avoided. Even in very low concentrations of
    ammonia, brass that is stressed by either residual or applied tension will
    spontaneously crack by ‘stress corrosion’, a phenomenon first observed
    many years ago and at that time called ‘season cracking’. For failure to
    occur in this way, two conditions must apply: that the brass is under stress,
    and that ammonia is present (Mercury and moist chlorine may also cause
    similar failure). Internal tensile stresses caused by cold working, as in the
    cold drawing of tubes or cold bending of pipework, are sufficient to make
    brass susceptible to stress corrosion cracking. Under such circumstances
    a stress-relief heat treatment is advisable before such items are put to use
    in aggressive environments. Test methods to ensure that the heat treatment
    has been effective are detailed in relevant Standards.


    Annealing made perfect.

    Of all the folks involved in reloading and trying to do it themselves this father / son outfit in New Zealand is one of the few who actually have hardness test data to back up their results. Their site contains a lot of information about the flash annealing process. I stumbled on them looking for info on who; if anyone uses induction heating for this part of the process. Anyways I would urge folks to examine their results, test methods etc. Note that a good bit of what they are doing is related to the use of induction heating and the constraints it places on them to get consistent results.
    https://www.ampannealing.com/
    Note that I have do not own their product, and or have any connection to them, but I am impressed by the attention to detail and their commitment to attaining consistent results, backed up with actual hardness testing and testing of neck tension via measuring bullet pull force. It is also nice to know that we have folks all over the world that appreciate our hobby as do we.

    Summary:

    What is a poor DIYer to do?
    Certainly it is an undisputed fact that for multiple reloading of any brass some sort of flash annealing needs to occur. If you are reloading simply to save money on your plinking habit you can probably get away with annealing every other reload. If you are doing some sort of wildcat or trying to resurrect an obsolete caliber with resizing etc. then for sure you would need to anneal. For those who are trying to wring the most out of their load/gun then consistent results are key.
    Measuring the temperature. I started looking at this from the point of view that certainly there must be a better way to gauge the temperature than going through the tempilaq process. The main issue is it only tells us that we arrived at and or exceeded a particular temperature but gives no information by how much, and generally is only useful for setup, tho I suppose you could use it on every 10 or 20 cartridges or so in a batch to see how consistent the process was.
    There are other ways, notably the infrared temp devices, though the typical ones used for home shop uses are just not up to the task. Certainly there are industrial devices that could be used but unless you can stumble on an ebay deal or auction site I doubt a hobbyist is gonna spend the coin.
    The amp folks note that their initial testing was done using FLIR camera and while these are also very nice they are not cheap either.
    One of the issues I see with the torch annealers is getting consistent results. Basically it means spending a lot of setup time adjusting the flame, using tempilaq on one or more cartridges then assuming it stays consistent for a particular batch.. sure would be nice to be able to measure the temperature …
    Another idea was inline air heaters/heat guns. These are widely used in industry for various processes and can easily hit the temperatures needed for annealing. Many of them even have readout of the temperature they produce and may at least eliminate some of the variability’s involved with using a torch. I am not sure if anyone has tried it.
     
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