Tig Welding aluminum. Large etching at startup

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I'm having a bit of an issue with large etching zone in the region of where I start my arc.   Is there a way to reduce this to keep the weld looking more uniform? Picture of what's happening. You can see it on the right of the pipe. Cheers, Matt
Reply:My machine doesn't have any balance or frequency adjustments. Mine has a tendency to create a similarly large etching zone at start. I have been able to tone it done with a more deliberate arc start (hitting the pedal a little harder) and prepping the tungsten with a shorter point. A longer point spreads the arc cone more. I can still see a wider etch zone on starts and restarts compared to the rest of the bead, but it's better than before.
Reply:Thanks. Would it be the arc length too maybe? I don't think I change it really, but its the only thing I can think of. I do have balance and frequency adjustments pretty much set where I like it for this piping, just the starts make that etch. I do roll onto the pedal too though instead of just mashing it.
Reply:What sized tungsten are you running? What alloy? What is your balance set at? If your tungsten is too big you will get a lot of arc wander till you get a good strong arc. More EN balance will help reduce wandering and etching in general. I have moved away from the traditional rounded tip and started running a pointed tip one size bigger than I would with a rounded tip. That along with the balance as far to the EN or penetration side of things as possible while producing a clean weld. The sharp tip allows for a crisp start and if setup right can stay mostly pointed aside from a small melted radius on the tip.Lincoln precision TIG 275Millermatic 140 MIG
Reply:Originally Posted by shlammedThanks. Would it be the arc length too maybe?
Reply:Originally Posted by yoshimitsuspeedWhat sized tungsten are you running? What alloy? What is your balance set at? If your tungsten is too big you will get a lot of arc wander till you get a good strong arc. More EN balance will help reduce wandering and etching in general. I have moved away from the traditional rounded tip and started running a pointed tip one size bigger than I would with a rounded tip. That along with the balance as far to the EN or penetration side of things as possible while producing a clean weld. The sharp tip allows for a crisp start and if setup right can stay mostly pointed aside from a small melted radius on the tip.
Reply:Originally Posted by shlammedI do roll onto the pedal too though instead of just mashing it.
Reply:I'm thinking you're not starting hot enough also.  Looks like your bead is wider and flatter where you're starting.  Looks like you're sitting there longer than need be.Should be hot, puddle, dip and go.You need to dip more often too.  Dimes too far from each other.Tubing and pipe is so much harder than it looks.What machine are you using?Last edited by Drf255; 06-23-2013 at 05:38 AM.TA Arcmaster 300CM3XMT 304S22P12 suitcase feederX-Treme 12VSOptima pulserTA161SMaxstar 150STLHypertherm PM45OP setupStihl 020AVP, 039, 066 Magnum
Reply:Originally Posted by papaharley03Try some scrap and floor the pedal. Then back off as you progress. See if that helps.Papa
Reply:LOL not my car.  I built the intake for this guy.I doubt any nitrous will actually go through it, but you never know.I know Im going to get some negative feedback from saying it but Im using a 2013 Everlast Powertig 200dx.  Its actually working pretty well for me.  The problem was around though when I had my Lincoln Precision 185.I usually dip more often, but it was a slow morning for me that day. I was shaking like crazy from a hangover.I will get some more practice in soon on aluminum and let you know if the quick jab to get the heat up helps, though it seems to be just while the high frequency unit is on that makes that cloud.
Reply:Jabbing the peddle gets you out of the high frequency faster.
Reply:I thought high freq was only used in DC.Lincoln precision TIG 275Millermatic 140 MIG
Reply:On my machine it does something at start up in both AC and DC. If I stab the peddle down and then lift back to my welding temp I get past that initial start faster with a less effected zone. I am sure they aren't all the same.
Reply:Originally Posted by VPTOn my machine it does something at start up in both AC and DC. If I stab the peddle down and then lift back to my welding temp I get past that initial start faster with a less effected zone. I am sure they aren't all the same.
Reply:I will try initiating a few welds tonight and report back.  Hopefully get something else off my list of things to make improvements on.
Reply:I would try a longer per flow. I am assuming your set up is using a roto meter type flow regulator. These flow regulators store gas and cause a huge rush of gas When flow is initeated. This could cause the large etching on start up because the etching will only take place in the area covered with argon. The large rush of gas increases the etched area. With a longer perflow the arc will initiate after the argon burst and the etching will be more uniform.
Reply:The longer pre-flow is a really good idea.  You need that sudden rush of gas (if you are experiencing such a rush on your particular setup) to settle down before the arc will ignite with stability.Another trick you can try is light up on a piece of scrap nearby, to get the tungsten warmed up (so use some decent current while doing this).  Then before the tungsten has a chance to cool off completely, move it to your workpiece and start the arc.  Might not be practical actually, but if it helps it will tell you that arc starting is a contributing factor here.  What tungsten size, grind, and alloy can make a big difference in arc starting.  (And like others here have mentioned, starting amps.)Hope this helps.
Reply:Just checked this thread from way back. Thanks for the suggestions. I will set some pre-flow in and give it a go this afternoon. Sent from my SGH-I317M using Tapatalk now Free