Aluminum Intake pipe, TIG welded with He/Ar mix

[jakeru]

Hey guys -

I am really liking mixing in a little bit of Helium for additionally concentrated arc heat, for any thick aluminum.

Here is a flange (1/4" plate of 6061-T6) fillet welded to an intake pipe (2.25"OD .065" wall 6061-T6 tubing.) I used 3/32" 4043 filler rod.

Prepped for welding:


After welding:




I didn't cut the hole in the middle of the plate until after I welded it. I did it that way to reduce distortion. But having the 1/4" plate being continuous, meant it would soak up more energy during welding and require more power for welding.

I used about 2.5 cfh Helium and about 12.5 cfh argon, with a #6 gas lens cup.

I used a 3/32" tungsten truncated point (like a crayon), 2% lanthanted. Only the very tip melted/balled.


I used 20% DCEP AC Balance (minimum on my machine.) The Helium seemed to really concentrate heat. It makes a puddle more effortlessly, and a deeper puddle, that penetrates much deeper, too. I set the pedal to give it everything it's got (200 amps) at full pedal down, but found that I didn't need to floor it. I probably used about 3/4 pedal to get the puddle going (maybe 150-160 amps?)

This is for my racecar. I'll be doing some more boost tube welding tomorrow, and hopefully wrapping up a new, experimental intake manifold for it.

Anyhow, really happy having some Helium at my disposal. It doesn't take very much to make a very noticeable difference!

[Velocity]

jackeru, was this welded with an inverter machine or old tranformer unit?
also, did you use a pulse setting while welding this?

[jakeru]

Welded with my Everlast Super200P inverter, of course. No pulse.

[dgarnier]

Since you only had to use maybe 150-160 amps? if you didnt have the Helium would you have been able to do the weld by flooring the pedal?

[jakeru]

Able to "get the weld done" on pure argon, yes with more difficulty in manipulating the torch so that the filler rod and the thinner (.065" tubing) material didn't melt, probably could have "managed". But I would bet, it would have given a different quality to the weld bead. I'm thinking, the weld bead would have been more "built up" on the surface, with less "wetted in" look at the toes of the weld bead, the weld bead surface wouldn't be as shiny but may look more dull and grainey, and there would have been a wider cathodic etch pattern. At least, this is what I've noticed in some back to back tests on various gas mixes on the same material.

Mixing in Helium is almost like twisting the A/C balance knob farther towards the "penetration" side (reduced EP%).

[SeanMurphy265]

I've been thinking about getting a bottle of helium. This is going to sound dumb, but could you get one of the party helium tanks and add it to a tig setup?

[hooda]

Just wondering how you incorporated the helium intothe argon. I have seen Jody's setup, which is a simple y-adapter setup where the 2 gases converge someplace upstream of the torch, and what you get at the torch is beyond me. I have also seen gas mixer on the action site made specifically for this purpose and the cost is around two GRAND!! Ridiculous. So, which setup are you running, and could you show some pics? Nice welds by the way.

[jakeru]

Hooda - this should explain:
http://www.everlastgenerators.com/fo...3962#post13962

But in short, I use a "Y", pretty much like Jody. And also FYI, I found that check valves are not even necessary, provided that both regulators have the same output pressure. This will not be a problem if you have two regulators of the same type.

If you have one regulator with a higher output pressure than another and "Y" them together, you could have the higher pressure backflowing through the lower pressure regulator's needle valve, and escaping out the lower pressure regulator's pressure relief valve (that could waste a lot of costly gas.) So what I would recommend with the "Y" is, two identical regulators. (Same brand, and same model if possible.) That will also make their flow characteristics more similar.

There is a minimum flow that I find a regulator (at least the kind I am using) can consistently and uniformly maintain; for the kind I am using, it is maybe about 2.5 cfh. If you go below that, like if I try just cracking the regulator open at maybe 1 cfh or so, I find the mix gets kind of "variable" and oscillates or wavers while you are welding, which is not really a good thing (you want a fairly consistent, controllable arc quality for the most part.) But, I've had very good results with this setup. It is also amazing to me how clearly the mix of He/Ar can be "heard" coming out of the torch cup. Helium makes a much higher pitch whistle than argon as it comes out through the torch orifices, and as the mix between the two gasses varies, so does the sound.

In fact, I just welded a repair on aluminum motorcycle frame the other day, and I mixed in some helium to better focus the heat with a small, sharp tungsten. Worked like a charm.

Here is the rule of thumb I have developed and utilized effectively as of late to determine how much overall flow to use when using a He/Ar mix - it is very simple: when I decide to mix in some helium along with my argon for TIG welding, I just keep the argon flow at the same place as where I would normally have it if I were otherwise TIG welding with pure argon and all the other same parameters (same stickout, cup size, etc). As I keep the argon flow the same as I would otherwise be using, I just add in some extra Helium flow on top of that, to effect the desired arc quality. 2.5cfh He, and 10-15 cfh argon is a pretty good setting (eg, for a 5 or 6 size cup). Or if I want some extra arc heat (if I want to penetrate even deeper or have even more concentrated heat), I can boost the Helium up a bit more, 5 cfh, even 10 cfh.

I don't see much need to go over 50% He. In fact with lots of helium, I don't get enough cleaning action on the surface. That is when you will also start to notice a red glow in the arc. Arc starts are noticeably more difficult with high Helium mixes, but 2.5cfh He doesn't hinder arc starts all that much. Usually first start on cold tungsten is the hardest, but if you re-start without much delay before tungsten has a chance to cool down, it will restart much easier.

[hooda]

Hooda - this should explain:
http://www.everlastgenerators.com/fo...3962#post13962

But in short, I use a "Y", pretty much like Jody. And also FYI, I found that check valves are not even necessary, provided that both regulators have the same output pressure. This will not be a problem if you have two regulators of the same type.

If you have one regulator with a higher output pressure than another and "Y" them together, you could have the higher pressure backflowing through the lower pressure regulator's needle valve, and escaping out the lower pressure regulator's pressure relief valve (that could waste a lot of costly gas.) So what I would recommend with the "Y" is, two identical regulators. (Same brand, and same model if possible.) That will also make their flow characteristics more similar.

So Jake, from what you're saying, I'm having trouble understanding. I would be under the impression that the flow in cfh would be a direct product of the pressure driving it. That would mean, in theory, that the argon pushing, say 15 cfh, meeting up with the He pushing, say 2.5 cfh, would have the argon pushing the He back to the regulator, thereby stopping flow. Now, this is my common sense theory, and, since I consider you as a "mentor" of sorts through your posts on this forum, I don't for a second doubt that you have it working. I'm just having trouble understanding how the pressures interact. when coming from two different sources. I just had a eureka moment to use as a new project. I will be starting a new thread. But in the mean time, please explain how this works without one backing up into the other. (Pictures might help). Thanks Again, Chris

[jakeru]

So Jake, from what you're saying, I'm having trouble understanding. I would be under the impression that the flow in cfh would be a direct product of the pressure driving it. That would mean, in theory, that the argon pushing, say 15 cfh, meeting up with the He pushing, say 2.5 cfh, would have the argon pushing the He back to the regulator, thereby stopping flow. Now, this is my common sense theory, and, since I consider you as a "mentor" of sorts through your posts on this forum, I don't for a second doubt that you have it working. I'm just having trouble understanding how the pressures interact. when coming from two different sources. I just had a eureka moment to use as a new project. I will be starting a new thread. But in the mean time, please explain how this works without one backing up into the other. (Pictures might help). Thanks Again, Chris

Hey Chris -

Let's start with a basic description of the inert gas system's components in a TIG welding setup. Here is what things are doing when the TIG machine's solenoid is opened and gas is flowing (i.e., when one is in the middle of performing a TIG weld):


Here is what the same system looks like after the solenoid closes. Note that the pressure in the space between the needle valve and solenoid rises to the flowmeter's internally regulated pressure.


When the solenoid next opens, this pressure can suddenly vent out of the TIG torch cup, with a sudden "whoosh" sound. (But usually after a fraction of a second, it calms down and a stable arc can be struck.)

Now, let's say we're going to "Y" in a second flowmeter into the system at the hose entering the TIG machine (between needle valve and solenoid.) If both flowmeters have the same internally regulated pressure (e.g., both are factory pre-set to 30 psi internally regulated pressure), the system pressures when the solenoid is closed are not going to be any different than if there was just one flowmeter in the system. And when the solenoid starts, a flow is going to start back up smoothly and proportionally through each of the two regulators.

However if the regulated pressure of the second flowmeter is higher than the regulated pressure of the first flowmeter (e.g., 50 psi on the second and 30psi on the first), the higher pressure is going to cause a backflow through the first flowmeter's needle valve after the solenoid closes. If the first flowmeter's floating ball gauge is not functional as a check valve (it is likely the ball could impede a reverse flow, while not completely stopping it), there can be a reverse flow through the first flowmeter's floating ball gauge as well. And then, if the regulated pressure of the second flowmeter (e.g., 50psi) exceeds the pressure at which the first flowmeter's pressure relief valve opens (e.g., 40psi), then the first flowmeter's pressure relief valve will open and vent the contents of the second flowmeter's cylinder. (especially if it is left overnight without remembering to shut off the cylinder valves.)

Even if the pressure relief valve (aka "overpressure safety valve") doesn't vent any gas to atmosphere, having unmatched flowmeters is unpreferable to matching flowmeters, for maintaining as consistent as possible of a gas mix as the solenoid goes through periods of remaining open, and periods of movement. Generally, when the solenoid stays open (IE: welding long seams) the gas mix is going to be biased towards the lower pressure gas, while as the solenoid cycles more frequently (IE: doing a sequence of tack welds spaced out far enough to trigger the solenoid to close) the mix is going to be biased towards the higher pressure gas.

Although I have yet to go through a complete tank of He yet, I haven't noticed much problems as long as I have the flow set high enough so the ball of the He flow gauge isn't "bouncing" up and down off its seat. Also, there is probable a certain degree of Ar/He gas mixture variability that can be tolerated when TIG welding without issues.