Thread: Little oxy set using disposable gas -- useful for occasional DIY or just a gimmick?

Originally Posted by Com_VC

I can't see any reason why you couldn't connect a tig torch to it and run it on stick mode, it's a DC capable machine.

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You are dead on the money. People have forgotten that an awful lot of TIG welding was done with the good old DC generator welders in years gone by. The UNIMIG Viper will definitely TIG weld, but will lack Lift Arc capability (far from the end of the world in my humble opinion). The slightly greater chance of tungsten inclusions using a scratch arc compared to a lift arc machine will not bother 99% of TIG users.
If money was no issue, then I would always go for a HF start AC DC machine and a new user will find HF start easier to learn with, but there's nothing wrong with a basic scratch start machine for budget/infrequent use.

Just in case: you can do very nice brazing with a TIG torch! You just have to use right bronze rod... Have a look on YouTube for examples.

Originally Posted by jhovel

Just in case: you can do very nice brazing with a TIG torch! You just have to use right bronze rod... Have a look on YouTube for examples.

Can you braze with TIG or only braze (bronze) weld?

I have done both with O/A but not with TIG. I would have thought that the heat from TIG would be too localised for brazing.

I assume by "braze" you mean braze weld but I am curious about the possibility of actual TIG brazing.

Jack

Originally Posted by Jack Ryan

Can you braze with TIG or only braze (bronze) weld?

I have done both with O/A but not with TIG. I would have thought that the heat from TIG would be too localised for brazing.

I assume by "braze" you mean braze weld but I am curious about the possibility of actual TIG brazing.

Jack

RE: TIG - Yes you can. Silicone bronze. Aluminium bronze, to name a few.
Hard to explain, but you don't form a puddle, you just dab the rod into the arc and heat zone, and it wicks to the heat.
Remember, while not ideal, arc length (tungsten to work) can affect heat focus...

Originally Posted by Commander_Keen

RE: TIG - Yes you can. Silicone bronze. Aluminium bronze, to name a few.
Hard to explain, but you don't form a puddle, you just dab the rod into the arc and heat zone, and it wicks to the heat.
Remember, while not ideal, arc length (tungsten to work) can affect heat focus...

Thanks. I guess I need to try it as it still sounds like braze welding. I haven't seen any TIG brazing on YouTube, it all seems to be braze welding.

I guess that's why you say it is hard to explain.

Jack

You can also MIG braze, but let's not get carried away with that, for now.

FWIW the American Welding Society (AWS) has a basic definition of Brazing and Soldering:
Brazing and soldering share a number of features.
Both are liquid-solid state processes as they
involve molten filler metal and solid base metal, which
do not melt or mix. In both brazing and soldering, metallurgical
bonds are produced by mutual diffusion
rather than by fusion. Predominantly, the molten filler
alloy diffuses into the base metal. Some base metal is
also dissolved, diffusing into the filler metal. Although
the fundamentals of bonding are the same for both
processes, the temperature required to effect joining
determines whether the diffusion process is considered
brazing or soldering. Brazing takes place when the
metal is heated to above 840°F (450°C), while soldering
occurs below this temperature.

Originally Posted by Commander_Keen

You can also MIG braze, but let's not get carried away with that, for now.

FWIW the American Welding Society (AWS) has a basic definition of Brazing and Soldering:
Brazing and soldering share a number of features.
Both are liquid-solid state processes as they
involve molten filler metal and solid base metal, which
do not melt or mix. In both brazing and soldering, metallurgical
bonds are produced by mutual diffusion
rather than by fusion. Predominantly, the molten filler
alloy diffuses into the base metal. Some base metal is
also dissolved, diffusing into the filler metal. Although
the fundamentals of bonding are the same for both
processes, the temperature required to effect joining
determines whether the diffusion process is considered
brazing or soldering. Brazing takes place when the
metal is heated to above 840°F (450°C), while soldering
occurs below this temperature.

Thanks but I'm more interested in the difference between brazing and braze welding with respect to TIG. According to AWS A3.0:

braze, n.
A bond produced as a result of heating an assembly to the brazing temperature using a brazing filler metal distributed and retained between the
closely fitted faying surfaces of the joint by capillary action.

braze welding (BW).
A joining process in which the brazing filler metal is deposited in the joint without capillary action or melting of the base material.

So far, all of the "TIG brazing" I have seen others do and on YouTube has been braze welding. I would take some convincing that "MIG brazing" is anything other than braze welding. The difference is subtle and comes down to the joint type and design, and the way heat and filler are applied.

You are right though, no need to get carried away - I am just curious.

Jack

Is not Brazing and Braze Welding just two different names for the same thing?

Originally Posted by China

Is not Brazing and Braze Welding just two different names for the same thing?

No, they are not the same. See the basic definitions in my last post.

Braze welding used to be called bronze welding if that helps.

Jack

Interesting when I did a welding course at Panorama TAFE ( long gone ) in the 80's using capillary action was soldering and was not done with bronze all brazing was achieved without capillary action

Originally Posted by China

Interesting when I did a welding course at Panorama TAFE ( long gone ) in the 80's using capillary action was soldering and was not done with bronze all brazing was achieved without capillary action

I think that most people who braze are actually braze welding and that is likely appropriate for the joints they are making. It only gets confusing when curiosity prompts me to ask a question about (real) brazing and everyone thinks I mean braze welding.

I have still not tried it myself, but I think TIG (and MIG) brazing are not realistic options. TIG and MIG braze welding are a different matter.

Jack

Originally Posted by China

Interesting when I did a welding course at Panorama TAFE ( long gone ) in the 80's using capillary action was soldering and was not done with bronze all brazing was achieved without capillary action

Your comment about training prompted me to check the training notes from the School of Mechanical Technology. They cover both brazing and braze welding.

Typical joints for brazing are all compatible with capillary action whereas braze welding joints are like typical welded joint preparations.

Jack


Typical Brazed Joints.png

Joint Preparation for Braze Welding.png

While I've usually used the terms interchangeably- AWS does indeed differentiate between 'brazing' and 'braze welding'.

AWS Literature confirms that 'Braze welding' uses joint design not intentionally designed for capillary action. Filler material would be face-fed at the point where the brazement is needed, as opposed to 'brazing' which would use capillary action as the action through which the filler material is deposited into the joint. It's a fine line, and I'd wager many would call both processes 'brazing', but AWS does indeed differentiate.

For anyone looking for the definitive guide- AWS Welding handbook, volume 2, chapter 12 dedicates over 50 pages to the brazing / braze welding process. On top of that, later volumes discuss at length, the brazing considerations for specific materials.

Interesting