What causes "Green" in the Arc?

[Blaster]

I'm having intermittent issues with contamination and I'm trying to follow some clues. Over the past few weeks I've been welding the same material for these Fireworks Racks I'm making. I've made thousands of the same welds, in the same material, using the same supplies and settings.

6061 with 4043 - 1/4" Angle and 1/8" square tubing Butt Joints. After I "cook" the start of the weld a bit, see the Shiny on both sides, add the rod and max the pedal (30/70 175Hz 185-250A) and the filler immediately forms a black speckled oxide layer on top of a ball. Nasty

I'm also seeing for the first time, along the ragged saw-cut edge sometimes, a Bright Green spot (in the plasma) that forms on one side or the other and trails away. Often it happens on one of the bad starts (I don't continue the weld when it does it). Is this Copper from somewhere?

I also have seen, on just one side of the 1/8" Thorated Electrode, Bluing. I have a good 12sec Post Purge so I'm thinking it's a shielding issue (I have also just changed tanks but this only happens 5-10% of the time so, I would think "bad gas" would be more consistent). I'm inside, out of any breeze, in the exact same location on the table as all the other welds. I have changed Tungstens several times, cups, and O-Rings. Raised & Lowered the flow some but, as I said, I've been using the same settings for so long now without this happening that I don't think I have something set wrong.

Trying to find some commonality to when it happens, using a different brush, Electrodes, different batch of filler (happens on both the 3/32 and 1/8 though). I have a CK Superflex WC Torch with the ArcZone Gas Lens "kit" (Really like those ArcTime Electrodes that came with That ) But what else can I look for and what's with the Green?

[performance]

Green is contamination of the tungsten, from either the filler or the base metal. You've mentioned nothing of your cleaning techniques before welding. A saw can contaminate the aluminum. It should be dressed back, and any oil on the blade can mess with things, and hence the carbon formation on the top. You may be overheating the tungsten too.

[Blaster]

OK, so the green dot I see on the edge of the cut isn't actually originating At that spot? It's streaming off the Tungsten and just showing-up at one tiny spot on the edge of a cut?

It's not something I've noticed before, maybe it's happened and I was just not looking for a problem then

This green thing happens on a cold electrode as I'm preheating right away. I've had it happen, changed electrodes, gone back and it will still show some green.

The bluing is something else I haven't noticed before and, as I said, I'm just noticing it on One side only. It seems to be on the Same side of the torch each time and got me to change the O-Ring on the push-on collet body and change to a new cup (didn't help).

I cut everything with a Dry carbide blade, I use a SS brush, I'll try Acetone and see if that stops it from happening...

[jakeru]

Do you have an extra tank to try?

You said it just started (although intermittently) after switching the tank, and that you've done thousands of these welds.

Another idea is if it just happens when adding filler, are you pulling the molten tip of the filler away from the shielding gas too quickly? Try to make a conscious effort to let the tip of the filler rod linger in the gas coverage (with torch angle pointing a bit towards it) and don't forget to post-flow.

Bluing on the tungsten is poor gas quality, gas delivery problem, inadequate post-flow...

[TheGary]

You have probably checked this but I will ask anyway. Are all your hose fittings and your flow meter all tight. It does not take much contamination to do what you are describing. If a fitting is even hand tight it will create a vacuum and suck in air from the room and contaminate the gas. Also check along the hose for a nick or a burn spot that might be letting it draw in air. If the cup on the torch is not tight it can pull in air also. If you have too much tungsten sticking out it can do it also. If you like a lot of tungsten stick out put a gas lens on your torch, it straightens the gas flow and allows more stick out before it starts to swirl and draw in air. I am just covering some posibilities of the cause, if I have repeated something allready stated. sorry

[everlastsupport]

You have probably checked this but I will ask anyway. Are all your hose fittings and your flow meter all tight. It does not take much contamination to do what you are describing. If a fitting is even hand tight it will create a vacuum and suck in air from the room and contaminate the gas. Also check along the hose for a nick or a burn spot that might be letting it draw in air. If the cup on the torch is not tight it can pull in air also. If you have too much tungsten sticking out it can do it also. If you like a lot of tungsten stick out put a gas lens on your torch, it straightens the gas flow and allows more stick out before it starts to swirl and draw in air. I am just covering some posibilities of the cause, if I have repeated something allready stated. sorry

I have seen a bad o-ring on the back cap cause this as well.

[Blaster]

Is this possible????

When switching tanks, to the one on my MIG machine over in the corner, I inadvertently rolled the knob on the flowmeter and tripled the flow and couldn't see it (I guess I was Not using the "same settings" after all ) I'm using the Gas Saver collet from CK but, would all this extra flow have turbulated anyway? The bluing on only one side and all? The welds I was doing were in the "crotch" if the 1/4" Angle, facing me, so I had earplugs in (that 175Hz is punishing...) and didn't notice the extra gas sound.

Hasn't happened since, I've swapped back to the refilled tank now. Well see....

[everlastsupport]

Is this possible????

When switching tanks, to the one on my MIG machine over in the corner, I inadvertently rolled the knob on the flowmeter and tripled the flow and couldn't see it (I guess I was Not using the "same settings" after all ) I'm using the Gas Saver collet from CK but, would all this extra flow have turbulated anyway? The bluing on only one side and all? The welds I was doing were in the "crotch" if the 1/4" Angle, facing me, so I had earplugs in (that 175Hz is punishing...) and didn't notice the extra gas sound.

Hasn't happened since, I've swapped back to the refilled tank now. Well see....

That could do it.

[Blaster]

First, I wanted to thank everybody for their insight and experience, and to say I haven't seen the problem return despite 2-days of welding.

AND

Had another thought....

Because I don't think I saw this problem on any of the lap joints, just the "cuts", I am recalling the 3 days I spent cutting (did it all at once, everything goes into a fixture so I was being really careful to be accurate). I knew I couldn't WD the blade to prevent the Alum form sticking so I just would stop every-once-and-awhile, when I heard the "clunking" and pick the blade clean. BUT, at some point, I put on a HF 10" 60-tooth blade I bought for like $20. It occurs to me that though I never oiled it in any way, I should have cut some wood a couple of times and washed IT in Acetone. I'm sure it was oiled to prevent rusting on the Big Boat and I just used it on my clean Aluminum....

Could have contributed to my trouble too.

[sportbike]

Seems like you are good to go now.

Post up a picture of the racks you are welding.

[Rambozo]

It's no problem to use cutting fluid on your saw blades. And a lot safer, you don't want to get aluminum welded to the blade. You will actually get a cleaner cut without tearing and leave a better surface. You just have to wash the aluminum before welding. Acetone will take off most cutting fluids like WD, and even a soap based cleaner will work on many fluids. Beeswax works pretty good for high speed carbide blades in aluminum, too.

[jakeru]

Sound like too much gas flow was causing your problem. (And yes, that can certainly cause the shielding problems you describe - more is not always better!)

You needn't question everything else you've been doing that, for your first thousand welds, didn't cause any problems. (Unless of course you are looking for a different, better result than you were getting on those, in which case, seeing some pics if your typical weld would help give you better guidance regarding whether further improvement should be sought).

For doing production welding, you may be more interested in adjustments that give you the same quality with increased productivity than ones for improving quality that is already sufficient. (For example, potentially switching to a bit larger diameter filler rod, to avoid terminating your weld bead so often to reach for new sticks.). Technique will also become optimized for production. (I assume you've learned to feed the filler completely with one hand without needing to terminate the arc to reposition the filler?)