TIG question on Alum

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Hi guys, I have a question...On my Miller 350LX with the pulser on(mind you, first tig machine I have run with pulse), on .125" 5086 Al, 140 amps and the pulser set at 50% on the back ground amps, 2 pps, 50% peak time, why do the welds look frosty? I have tried adjusting the back ground, and the peak but not diff., I understand the PPS and holy crap, don't run her up to far past three and try to keep up!When I make a pass the the pulser off (the old fashioned way) they are nice and bright.Is there any literature out there, or advise on the the pulse setting on these things?DanMiller 350 LX TigrunnerMiller 350P w/XR-ProMiller 211 AutosetMiller Spot WelderLincoln 140Hypertherm Powermax45 plasmaBridgeport millAtlas 12X40 latheBewo cold sawWilton 7x12 horiz. band sawUnihydro 42 ton Iron worker
Reply:I cant help you because i haven't experimented with pulse YET. I know a bunch of people are gonna come on here and say not to use pulse on aluminum. I would kind of agree with them if you haven't much experience. But probably one of the best, if not the best aluminum welders (work seen here http://www.marcellamanifolds.net/images/Images.html)mentioned that he had been experimenting with pulse and was getting some good results.www.performancealuminumfabrication.com
Reply:Well for .125" normal is 125 amps.Pulse amps alone you are at 105.   140 + 70 (50%) = 210 divide by 2 is 105 amps.So your cool there and then add in 50% time puts the heat down lower.Does the pulser work in AC for aluminum???
Reply:Not sure if this helps or not- just a page I have saved in my bookmarkshttp://www.pro-fusiononline.com/welding/pulseparams.aspEd Conleyhttp://www.screamingbroccoli.com/MM252MM211 (Sold)Passport Plus & Spool gunLincoln SP135 Plus- (Gone to a good home)Klutch 120v Plasma cutterSO 2020 benderBeer in the fridge
Reply:Thanks guys, I will just keep going the old fashioned way but if someone else chimes in I'm all ears!Do get me wrong the weld looks fine, wets out, but looks frosty.DanMiller 350 LX TigrunnerMiller 350P w/XR-ProMiller 211 AutosetMiller Spot WelderLincoln 140Hypertherm Powermax45 plasmaBridgeport millAtlas 12X40 latheBewo cold sawWilton 7x12 horiz. band sawUnihydro 42 ton Iron worker
Reply:Likely due to the low background amps, at 2% the arc is basically shutting off each time it pulses.  Just like you would find if restarting a weld without pulse, there is going to be a frost around the puddle where you first started.  Turn your background up and I bet the problem goes away.Have we all gone mad?
Reply:I presume you're using the pulser in an attempt to get an even "stack of dimes".  If so, that's fine, but there's little advantage to pulsing on material that thick unless you're trying to weld near an edge.  It helps on thinner material, and I sometimes use it on castings to agitate the puddle to help float out the contaminates, but then it's 30-40 pulses per second.As the jester pointed out, your average weld current is low for .125 aluminum.  At the low pulse rate and current, I think the puddle is solidifying before you advance the torch and the cleaning cycle is etching the bead just like the area ahead and beside the puddle.  Are you moving faster when you weld the same material without the pulse?  Step up the current and travel speed by 30% - 40% and the frosting may just go away.  JimDynasty 300DXSmith He/Ar gas mixerMM350PHobart Handler 120Smith LW7, MW5, AW1A
Reply:Originally Posted by 4sfedI presume you're using the pulser in an attempt to get an even "stack of dimes".  If so, that's fine, but there's little advantage to pulsing on material that thick unless you're trying to weld near an edge.  It helps on thinner material, and I sometimes use it on castings to agitate the puddle to help float out the contaminates, but then it's 30-40 pulses per second.As the jester pointed out, your average weld current is low for .125 aluminum.  At the low pulse rate and current, I think the puddle is solidifying before you advance the torch and the cleaning cycle is etching the bead just like the area ahead and beside the puddle.  Are you moving faster when you weld the same material without the pulse?  Step up the current and travel speed by 30% - 40% and the frosting may just go away.  Jim
Reply:I find that high pulse rates for aluminum allow me to use green (pure) electrodes with my inverter machine, without excessive balling on the end of the tungsten.  Zip.