wide etching on aluminum

[johnson697]

was welding on some 5052 .100 aluminum with #6 gas lense and got some wide etching ,frosting effect on the edges on the welds , but the weld looks great.

[everlastsupport]

What was the balance set at?

[johnson697]

these are some of the tanks i welded this week

[jakeru]

My understanding of gasses is that different gasses have different voltage requirements to initiate and sustain an arc through them. I've sure noticed it when say, you weld through a container that outgasses something nasty and non-inert (like water vapor) that wreaks havoc with a previously stable TIG welding arc, and sends that arc suddenly blowing off to the side considerably (like an inch or more!), presumably where there is still inert gas capable of sustaining an arc at the voltage being used. So it makes sense to me, that changing the cup configuration actually could change the cathodic etch pattern.

In fact, I've thought I've noticed that using a large diameter gas lens does indeed enlarge the diameter of the cathodic etch pattern, all else being equal.

I'm not saying it's a good way to sufficiently control the width of the cathodic etch all by itself, but I do believe it can have a small difference. Changing the gas flow (and travel speed plus current output being used as previously mentins) are other variables that can influence the etch pattern. By all means, yes, I would recommend experimenting with different size cups and types of collet bodies (gas lens versus non-has lens) to try to arrive at the characteristics you desire - these components are available for a relatively low cost, so it's easy to try.

If your budget is a little higher, with all the aluminum welding you're doing, you might want to try a helium-argon mix. Mixing Helium in with the Argon *definitely* reduces the width of the cathodic etch pattern. In fact, IME, if you mix in too much Helium, you won't get enough cleaning to even keep the puddle itself clean! It changes other characteristics of the arc advantageously for welding aluminum also, IMO.

Too bad there's not an easy way to check what kind of AC balance your 250EX is actually kicking out. (e.g., to verify if it is indeed, putting out 90% EN 10% EP as advertised.)

I remember there was some posts a while back about some people's IGBT machines not putting out the specified AC balance. It took a pretty experienced and knowledgeable weldor to suspect this, and then someone confirmed it. Everlast replaced some boards or something and corrected the problem. Could be something to check out. (Making sure your machine is really putting out its advertised AC balance adjustment range...)

Edit: here we go, the thread I was thinking of:
Super wide etching on Aluminum!

[johnson697]

what kind of mix would you do?and im thinking about getting a #4 cup to use on my torch,i have a #6 gas lens on it right now.

[jakeru]

If you're looking at experimenting with a pre-mixed bottle, something in the area of 25% He / 75% Ar is probably a useful area. You're going to maintain good arc starts and get very noticeable benefits from Helium in that general range. I have a separate Helium and Argon bottle (and mix my own) and often I will just run just a very small amount of Helium, rarely over 33% He. It has really nice arc qualities for welding aluminum and is great for penetration or welding larger, thicker things.

A #4 cup is VERY small; there is a dramatic difference in its surface area compared to even a #5 cup (just to be aware of...) You'll may need to turn down you flow rate to avoid turbulence. In fact a #4 will work well with very little gas flow (like 8cfh or so Argon.) Definitely try a #5 cup also.

You should have already tried turning your EP (AC Balance knob) down to the minimum if you haven't already. You might want to compare your test beads to that those shown in the picture at the end of the thread I linked to above. If you aren't getting the same results, try and find someone with an oscilloscope test what AC balance range your machine is putting out. The 250EX is rated to put out 10% EP (90% EN) with the AC balance knob turned all the way counter-clockwise. At that setting you really shouldn't be getting much cathodic etching. Edit: here we go, this post has pictures (indicated as "NEW") of expected 250EX cathodic etching:
http://www.everlastgenerators.com/fo...=3932#post3932

Also, what tungsten are you using and how are you prepping its tip? I've found with a big, balled tungsten, seems to spread the arc out wider (and thus, the cathodic etching out wider as well.)

Happy experimenting!

[cbmkr]

I had the same problem AC Balance is a little high, the frost is the cleaning action,Balance can be lowered on clean material and you will have little or no frost or etching.

[johnson697]

around 9 oclock position but then i started to urn it up and down with little difference in the etching,does the gas lense have anything to do with this ,not a standard lens.

[performance]

Etching also can be caused by moving too slowly with too little amperage to get the heat into the metal quickly. If we exaggerate it for the purose of demonstration, an arc held at 10 amps in the same spot on thick aluminum will grow a wide etch zone regardless of where the balance is set.

To see if the balance is working, turn the balance up to 60% and see if the tungsten is balling. In fact, you should get some around 40-50% Do you have the EX? If so, go to about 20%. On the other models just set it at the minimum setting of 30%.

[johnson697]

Yes it did ball up,and yes i do have the ex.Had my amps around 180,but not sure how much i was actually using while i was welding but i would guess around 110 to 130 amps because i was only using a little over half of my pedal while i was welding .Had a guy i work with tell me to take off the gas lens and use a standard lens ,gonna try that tommorrow.

[zoama]

Yes it did ball up,and yes i do have the ex.Had my amps around 180,but not sure how much i was actually using while i was welding but i would guess around 110 to 130 amps because i was only using a little over half of my pedal while i was welding .Had a guy i work with tell me to take off the gas lens and use a standard lens ,gonna try that tommorrow.

The gas lens has nothing to do with etching.

[fdcmiami]

The gas lens has nothing to do with etching.

anyone welding for 12 years and claiming to have welded some of the fuel tanks shown in the photos would know that.

[johnson697]

i am using both lanthanated 1.5% and also thoriated ,but try to stay with the lanthanated for my aluminum ,and i dont ball my tungsten up.

[performance]

Thoriated won't ball either, if it's less than 40%, which is where it should be located at anyway.

[johnson697]

you can also check out some more tanks at dadscustomintercoolertanks.com

[performance]

At what point was it balling? Balling is a indicator of cleaning action, as more heat is forced on the tungsten in DC+, which is the cleaning stage of the cycle. IF you were getting balling at a minimum setting of 10% or even 30% then there may be an issue, but if it is up around 40-50% when balling occurs, then it is working as it should, and the etching is an environemental or operational issue.

[johnson697]

I dont think there is an issue with the machine ,the balling of the tungsten was around 50-60 %.

[fdcmiami]

you can also check out some more tanks at dadscustomintercoolertanks.com

....coolertank.com

since i have spent, off and on, about 20 years in the vicinity of marina mile in ft lauderdale, 17th street causeway, and in and out of shops south of state road 84, east of 95, i have had the opportunity to see many quality tanks built. for the most part and i mean almost all, (granted we are in a marine environment) they are fabricated of 5052 H32, 5083 and 5086 sheet.

not to say that 6061 is not used but it just does not have the formability characteristics of the 5xxx series and in the t6 condition requires a minimum bend radius of at least 2t to guard against fractures on the bend line. the tanks pictured are very well done, the welding looks excellent but beyond that they are nothing special and nothing that you can't see on a regular basis in south florida. also, i would like to point out that tanks are fabricated of equal quality using transformer machines whose date of manufacture more than likely predates your date of birth.

etching, or what otherwise is known as the heat affected zone (HAZ) is a pretty common topic of discussion due to the fact that minimizing it is a way to insure that your tank is less likely to have a failure in that area. so, for someone to state, and also to ask some of the questions you have posed, that they are unfamiliar with the subject after 14 years of welding seems quite a stretch. in fact the more you post the bigger the stretch, at least to me, it seems.

good luck on your sale of the ex; learning to be flexible when trying to make a sale is something that comes with experience.

[DaveO]

Did this post include photos at one point?

[johnson697]

No i havent posted pics on these tanks yet ,i will this weekend.