Marshall Reloading - Brass Annealing Machine

[Casting Timmy]

Here are some plans I have drawn up for a brass annealing machine. It will spin the brass around it's own axis and in a circle around the motor shaft as well. I am starting to work on machining this, but I wanted to post the plans on the site before I forget or lose these plans.

[Casting Timmy]

I have some cartridge brass reloading cliff notes I will try and make readable and post here as well. We have the ASTM material hand books at work and I was able to read about annealing brass, it was very interesting the things I did and didn't learn about it.

[drhall762]

That is pretty slick. Thanks for posting them. Might have to make that one of my class projects.

[Casting Timmy]

I have the center metal piece built, just need to work on the cartridge holders for it. Still have to buy all the parts from McMaster, then build a stand for it and make a propane mount.

[Casting Timmy]

Cliff Notes from American Society of Metals Materials Handbook 9th Edition

Volume 2 Properties and Selection: Non Ferrous Alloys and Pure Metals

Annealing – softening the metal, causes recrystallization

Stress Relieving – Reducing internal stresses to reduce the chance of the material cracking from season cracking or corrosion fatigue in service. Below the annealing temp and does not cause recrystallization or softening.

Annealing is done by heating enough to cause recrystallization, maximum softness is obtained by heating higher to cause grain growth.

Mainly influenced by metal temp, time at temp, amount of prior cold work


Rate of heating and cooling except in certain alloys is not critical.

No specific time/ temp can be given due to it varies so much due to the material and the cold work that was previously done to the material. Different amounts of cold work and how it was done, will result in different time/ temps to anneal.

Average grain size is the best method to determine amount annealed, but hardness can also be used to determine how much it was annealed.

Stress corrosion cracking “season cracking” is from forming the brass below the recrystallization temperature, which leads to surface stresses in the material.

Corrode faster in stressed condition.

C26000 Cartridge Brass 500F stress relieving temp
C26000 Cartridge Brass “575F Recrystallization temperature for .045mm initial grain size and a cold reduction of 50%.”
C26000 Cartridge Brass 800-1400F annealing temp

Material Specific Material Properties:

The amount of chromium and iron in cartridge brass affect the annealing properties.

“Highly susceptible to season cracking in ammoniacal enviroments”

It’s been a while since I’ve looked at that book, I’m sure some parts are direct quotes and others are cliff notes. Here are my personal conclusions after reading the material and also comparing it to some of the existing know methods people use.



Heating
Some people use a propane torch and others use lead, either way puts heat into the brass. I would say one advantage to using lead or a similar bath would be that the temperature is more consistent batch to batch than the flame method.



Cooling
Cooling the brass in water does not affect the annealing process directly, but does indirectly by it affects how much heat and for how long the brass was at a heat high enough to change it. Imagine heating up one piece of brass to your ideal temperature and for your ideal amount of time and then burying this piece of brass in sand. Now take another piece of brass and heat it exactly the same and dunk it in water. The piece of brass buried in the sand will have a slow cool down rate, so it could spend more time above required temperature for change. The piece dunked in the water will go well below the temperature required for change very quickly. In the real world no one is burying their brass in the sand after heating, but continually piling hot brass up in a metal container will make your total time above the temperature required for change dependent on where the brass is at in the pile. Pieces on top will cool first, or maybe the ones sitting on the side of the container and the last pieces to cool will be in the center of the pile.

I think the best reason for involving water in the process is to make the process consistent from piece to piece. The inconsistency of cooling rate will be a greater factor the higher above the temperature required for changing the brass. If you take the brass 5-10 degrees over the temperature required for change, the cooling process won’t have a big effect. If you take the brass to 2-3x the required temperature for change, the cool down process can have an affect if it’s different between pieces (Ex. dumping them in a big pile).



Correct Time and Temperature
This is where it starts getting gray and there are no set parameters for annealing. Comparing different pieces of the exact same lot of brass that are all the same hardness, but where cold worked differently to get that hardness will require annealing processes. This is why the books only list guidelines and considerations for the process.
The short version is that I will use a propane torch and just make sure I don’t get other areas heated higher than desired (Ex Bottom of the brass). A lead pot of other heated bath can be used, but keep in mind you need a certain amount of energy to do something to the brass. I only mention this as using the lead method will require a longer time to get the some results with using a torch method. I don’t worry about lead sticking to the brass and the lead bath might give the advantage of reducing oxidation during the process, but I just don’t want to mess with the extra effort of doing it. Even if there was a great machine to do it, I just don’t want to mess with the time waiting to heat it up.

[jmorris]

These videos may help.

This one shows the brass being heated just a little too much. Note at the end of the cycle the normally blue propane flame turns orange.




This is what you are looking for, the flame never changes color, even color around the case neck and it's cool enough to hold right after heating.



Setting cases in water when heating them allows one to over anneal the case, ( I am sure you have read or heard someone talking about heating a case to some shade of red or a "glow", all too much) without risking heat migration into the case head.

You can ruin a case by making the mouth too soft but you can make it dangerous if you make the head too soft.

[dmvelarde]

Where or how do you set up the tourch to annealing. I noticed that you were going to McMaster Carr to purchase the rest of the material for the touch strand. I just hope it's not there late to ask these questions