MIG Welding Aluminum in what Mode?

[ampdog]

I have only been welding for about a month. I have been reading up on welding Modes. Sort of after the fact cause I got pretty good at welding 1/8 Aluminum through trial and error. But, I figure as soon as I go to a different metal (change alloy and/or thickness) I will be right back at the drawing board. So, I want to better understand what needs to be in place before I start. I'm pretty sure I have the basics from reading articles and from an earlier thread on this forum (which was extremely helpful).

Anyway, my question is; Do I always need to be in Spray Mode to weld Aluminum? And if my tip is not recessed into my nozzle, does that mean that I'm not in spray mode? Or can i still get there just by turning up the voltage?

Also, since I use 100% CO2 to weld steel and 75%/25% for Alum., does that mean I always use short circuit mode for steel and Spray mode for Alum. (by default)?

[Dan]

Re: MIG Welding Aluminum in what Mode?

Originally posted by ampdog
I have only been welding for about a month. I have been reading up on welding Modes. Sort of after the fact cause I got pretty good at welding 1/8 Aluminum through trial and error. But, I figure as soon as I go to a different metal (change alloy and/or thickness) I will be right back at the drawing board. So, I want to better understand what needs to be in place before I start. I'm pretty sure I have the basics from reading articles and from an earlier thread on this forum (which was extremely helpful).

Anyway, my question is; Do I always need to be in Spray Mode to weld Aluminum? And if my tip is not recessed into my nozzle, does that mean that I'm not in spray mode? Or can i still get there just by turning up the voltage?

Also, since I use 100% CO2 to weld steel and 75%/25% for Alum., does that mean I always use short circuit mode for steel and Spray mode for Alum. (by default)?

75/25 on aluminum? Is this an argon/helium mix? I hope you aren t using an argon/co2 mix. 100% argon or a argon/helium mix is the gas to use on aluminum.

Very thin aluminum can supposedly be done in short circuit transfer. However, I have never tried it. Thicker aluminum, generally 14ga. and up is done in spray transfer mode.

The contact tip being recessed or flush with the end of the nozzle has no determining factor on whether or not you are in spray transfer mode.Spray transfer is achieved by using the proper shielding gas and then adjusting the wirespeed and voltage to the proper settings to achieve spray for the material thickness that you are going to be welding on.

Depending on the size of power source that you are using Co2 is going to allow you to either use short circuit transfer only, or short circuit and globular transfer on steel.

[Hobart Expert Dave]

As Dan Said you will only be in short circut transfer on steel using 100%C02. The recessed tip will not be a factor. On Aluminum use 100% Argon or the Mix Argon Heilium. The C25 will not work very well with aluminum. Adjust the voltage higher to achieve the spray.
Thanks
Dave Evans

[ampdog]

Thanks for the reply!

Sorry about that...... My questions are in the right vain, but I mis-typed when I was rattling off the gasses. I am using 100% Argon to weld Aluminum and Argon/CO2 for steel.

So, what is the significance of the recessed tip?

And if I use 100% argon to weld thin Alum. will short circuit mode happen or does it stay in spray mode due to the gas? Is it possible (ever necessary) to achieve spray mode on steel using the mixture?

Not trying to beat a dead horse, just trying to get a clear idea where the boundaries are for each mode.

[Roger]

A resessed tip helps maintain shielding with longer stickout. Aluminum is better electrical conductor than steel so a little longer aluminum wire sticking out from contact tip will have about same resistance as steel with less stickout. Burn back to contact tip is caused more by too slow wire feed for voltage, feed problems or dirty contact tip but a little more stickout gives a margin of prevention expecially with spray transfer with its higher voltage.

[ampdog]

Thanks Guy's

Now that I understand a little better my aluminum welds are getting more consistent.

Something else that I'm noticing in spray mode is that gravity has a much greater impact on my bead. When I was doing steel I did pretty good with my material at some crazy angles. But in spray mode (alum.) it seems like I mis my joint often unless I situate the material to be flat and / or directly below the gun.

For instance doing a T joint the way it is demoed in the millermatic video is not in my skill set , not in spray mode. Unless I tip the material so that the 90 deg angle of the T joint is pointed straight down and the gun is pointed right down into it like a trough. Then I get perfect welds. But, thats easy to do for a small piece of material that I can manipulate easily. It's not going to be that easy with bigger pieces of metal. So, what the key get penetration on both sides of the T joint in spray mode?

[Dan]

Originally posted by ampdog
Thanks Guy's

Now that I understand a little better my aluminum welds are getting more consistent.

Something else that I'm noticing in spray mode is that gravity has a much greater impact on my bead. When I was doing steel I did pretty good with my material at some crazy angles. But in spray mode (alum.) it seems like I mis my joint often unless I situate the material to be flat and / or directly below the gun.

For instance doing a T joint the way it is demoed in the millermatic video is not in my skill set , not in spray mode. Unless I tip the material so that the 90 deg angle of the T joint is pointed straight down and the gun is pointed right down into it like a trough. Then I get perfect welds. But, thats easy to do for a small piece of material that I can manipulate easily. It's not going to be that easy with bigger pieces of metal. So, what the key get penetration on both sides of the T joint in spray mode?

Ampdog

try dropping your gun angle downward a little and let the force of the arc push the weld metal up onto the vertical leg.