Why do you need two different types of gases for mig and tig? (generally speaking)
And what happens if you use straight argon for mig... argon/C02 with tig?\
Just curious.
You can use 100% Argon with hardwire or outershield fluxcore. The hardwire does not weld as nice with 100% as 75% / 25%. Im not sure why though. As for TIG with 75% / 25% The carbon in the CO2 contaminates the hot tungsten and makes for a not so nice weld.
Depending on the situation, the things to consider are: arc energy, penetration, arc stability, and spatter. You need to determine what gas or combination of gasses will give you optimum performance in those areas. Brian is correct in not using CO2 for TIG. Generally speaking, 100% argon is the best all-around gas for TIG. A 75/25 is best all-around gas for solid wire mig and if you are using a dual-shield mig wire than go with 100% CO2.
Jim
Pipefitter/Weldor out of Local 396
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Pipefitter/Weldor out of Local 396
Millermatic 252
Dynasty 200DX
Maxstar 150 STL
Spoolmate 100
Hypertherm Powermax 85
Miller Digital Elite
JD2 Model 32 Bender
Emerson 7120 Horizontal/Vertical Bandsaw
Oxy-Gas Torch outfit
Generac XP8000E Generator