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motorworks
12-15-2003, 10:30 PM
Hi
I have a project to do over the xmas break that involves welding brass.Not sure of the type only that the material is approx 15-20 years old and the equipment came from Germany.(Shoe making dies)
I was wondering what process to use,(Mig,Tig or Gas) and what type of rod.The material is approx 3/16" thick
regards
eddie

SGW
12-15-2003, 10:45 PM
Being pretty ignorant of welding in general, I'd probably use silver solder.

DR
12-15-2003, 10:53 PM
We machine lots of decorative (architectural details) of 1/2" to 1" solid brass rod. My customer TIG welds these with silcon bronze rod.

After the welding we get some back for further machining. As-welded they don't look pretty, but when we machine through the welded areas it appears solid with no porousity. There's a very slight color difference between the brass and filler material which is barely visible after polishing.

I think brass has some percentage of zinc so this is a process that should only be done with good ventilation.

CCWKen
12-15-2003, 11:37 PM
You can also just braze it with gas. As DR says, don't suck zinc fumes!

Evan
12-16-2003, 03:40 AM
Brass has 33 to 37% zinc. If it is a free cutting alloy then it has 1 to 1.5% lead as well. You really don't want to inhale the fumes from it. If you do then you will learn what metal fume fever is like.

Brass is usually brazed or silver soldered, not welded. You need to preheat the pieces if they are of any size as the copper content (around 62 to 67%) will conduct the heat to all of the pieces in a hurry.

[This message has been edited by Evan (edited 12-16-2003).]

Dr. Rob
12-16-2003, 04:43 AM
TIG works okay, but depends a bit on the specific alloy. I've used argon as a shielding gas. Strangely, it works well sometimes and other times not at all; I've never been able to make a science out of it. Only thing I've noticed is that it sure sucks heat, almost like welding copper.

MIG in its usual configuration I would say is completely hopeless, but I've never tried tuning one to specific application of brass. You know, different gases, fillers, amps and such- there are a lot of parameters to dial in.
Gas, I don't know.

pgmrdan
12-16-2003, 06:41 AM
.

[This message has been edited by pgmrdan (edited 03-08-2004).]

torker
12-16-2003, 09:27 AM
Hi.. Noob to this board. I weld a fair amount of brass and this is my experience. Yes... you do need good ventilation! Do not breath the fumes. I use Tig w/argon and standard brazing rod. Knock the flux off the rod and polish ALL the remaining flux off. Grind/file around the weld area. It almost seems like old brass has oxides the same as aluminum and that you have to remove it from a wide area around the joint. If you don't it seems to migrate into the weld puddle. The most important thing I've learned about this is.... it does take a LOT of heat to initiate a puddle. Once the puddle is started you have to back the heat off in a hurry and start adding your filler. It will look like crap as you are welding it and it is very hard to control. Add a few dabs of filler and then you better stop and let it cool (for small parts). If you don't the whole thing will slump into a molten puddle. Clean/ file/grind before restarting your weld. It does NOT look pretty but it usually produces a nice clean build up under the ugly mess.

chipeater
12-16-2003, 10:02 AM
Cartridge Brass (260)(also called 70/30)
Copper - ~70%
Zinc - ~30%


Bronze (SAE 660):
Copper - 83%
Lead - 7%
Tin - 7%
Zinc - 3%


See www.matweb.com (http://www.matweb.com)

[This message has been edited by chipeater (edited 12-16-2003).]

[This message has been edited by chipeater (edited 12-16-2003).]

JCHannum
12-16-2003, 10:20 AM
There are many alloys of brass and bronze, and the terms are sometimes applied erroneously. Brass generally has zinc in the 25%-35% range, bronze is in the 1%-3% range, but manganese bronze has zinc in the higher amounts.
I would recommend O/A welding or TIG. Problems with TIG and poor weld quality are probably associated with varying alloys, much as you cannot weld leaded steel. If you have TIG available, and it works, it is probably the better method due to th high heat conduction of the brass, but O/A will work just fine.
It would be helpful, if not vital, to find what the actual composition of the dies are, as welding with standard brazing rod may leave too soft of a deposit for the intended application. If you are merely trying to join two pieces of metal together, it is probably OK, but if you are building up worn surfaces, it might not be the best choice.

pgmrdan
12-16-2003, 10:30 AM
.

[This message has been edited by pgmrdan (edited 03-08-2004).]

wierdscience
12-16-2003, 10:20 PM
Get some scrap pieces and practice first!It requires so much heat that there is a very fine line between welding and a blob of brass on the floor.

I for one gas weld it using borax or commercial brass brazing flux the joints must be absolutely clean and free of oil etc.

As for tig,yes its supposed to be possible but I have only tried it once with mixed results.Ibew told me of a guy who tigs inside a sandblast cabinet purged with argon,sound like the way to go if you try tig.

JCHannum
12-16-2003, 10:23 PM
Make sure you are on the outside of the sandblast cabinet though.