I just want to say a couple of thing about the myths in MIG welding.
1.- You say with more than 20% CO2 YOU CAN NOT GET SPRAY TRANSFER. THAT`S NO TRUE. YOU CAN PRODUCE SPATTER FREE SPRAY TRANSFER WITH ARGON + 20 CO2 WITH ALL COMMON DIAMETERS OF MIG WIRE. SET THE FOLLOWING PARAMETERS: WIRE DIAMETER 0.035. 420 IPM AND START WITH A MINIMUM OF 27 TO 28 VOLTS. ONCE SPARY TRANFER IS STABLISHED INCREASE THE VOLTAGE BY 2 OR 3 VOLTS SO A DISTINCT GAP OF 3 mm EXIST BETWEEN THE WIRE TIP AND THE WELD.
WITH ARGON + 25% CO2 YOU CAN GET SPRAY TRANSFER WITH WIRE DIAMETERS 0.045 AND LARGER. SET TEH WIERE FEDEER TO 420 IPM, 35 VOLT. HOWEVER THE WELDER PREFER TO WORK WITH LOWER PARAMETERS.
2. TO WELD STAINLESS STEELS WITH ARGON + 3%O2 IT`S NOT A GOOD PRACTICE. THE OXIGEN IS VERY OXIDIZING AND THE STAINLESS STEEL IS VERY AFFINITY TO OXIGEN. THE RESULT: A SOOT BLACK OXIDE ON THE METAL DIFFICULT TO CLEAN. I RECOMMEND TO USE A ARGON + 3% CO2 FOR STAINLESS STEEL APPLICATIONS. THIS PERCENT OF CO2 DOES NOT AFFECT THE CARBON CONTENT OF THE STEEL.
3. ARGON + 4 TO 8 % O2 ARE CONSIDER A LOW ENERGY MIX. THE STEEL WELDING DOES NOT BENEFIT OF THIS. THE RIGTH MIX FOR CARBON STEEL WELDING APPLICATIONS ARE ARGON + 15 - 20 CO2 (THICKNESS 2.5 AND LARGER). THIS MIX IMPROVE THE ELECTRON FLOW, INCREASE THE PENETRATION, BETTER WELD FLUID, LESS POROSITY POTENTIAL, PROVIDE A MORE DENSE, WIDER, AND HIGHER ENERGY PLASMA, LESS SENSITIVITY TO MILL SCALE.
4. THE O2 IS NOT STRONGER THAN CO2 IN TO MAKE A FLUID WELD POOL. SEE POINT 3.
5. I AGREE.
6. I AGREE.
REGARDS
MIGUEL.