Weld-Pak 155 and aluminum

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I have a weld-Pak 155 and have used it w/ flux-core for years. No problems. I just bought the kit to upgrade to gas and the kit for aluminum, plus 80 cu bottle Argon. Made all the conversions, and welds look like garbage. Figured out I had to switch polarity. First weld looked good but no strength/ penetration. Subsequent welds are very poor. Tried all different power and speed settings. Wire is bird-nesting repeatedly. I think this is because the tip is getting hot and wire is expanding and jamming in tip. I know for a fact that the wire is hanging up/melting in the tip, and I think this is the birdnesting cause. I am using .035 wire and tip. Should I move up a tip size? Gas is running at 25, inside garage, no wind. Welds appear to havew very little penetration at all, and break very easily. Any input is greatly appreciated. I am not a welder, but Uncle Sam trained me to be about a gajillion years ago, or so it seems. Just a hobbyist now. Thank you.
Reply:I don't own a mig, but I used to work with one at work regularly to weld aluminum. We used a spoolgun, the reason being that aluminum wire birdnests very easily when trying to push it through the liner to a regular torch. Spoolguns are expensive though, and you may not want to buy one for occasional use. You may have better luck if you are very careful to keep the cable to your mig gun in as straight of a line as possiblble. The wire should be easier to push through the liner if it is kept pulled straight.
Reply:I agree with Joe, keep the liner straight as you can. It helps to blow out the liner with air when changing from steel to aluminum, if you don't change the liner. Also, aluminum has to be clean. Stainless steel wire brushes or at least a new brush never used on steel. I've found that aluminum mag wheel cleaner to wash off the aluminum prior to welding or Duponts Aluma prep33. The best precleaner I've found is a stainless steel wire wheel for a grinder.Weldtek
Reply:Oh yeah, the wire melting and getting stuck in the tip is likely happening because the wire has birdnested and quit feeding through, not the other way around.Hope we helped.
Reply:Thank you, I had not thought about that. I will go back at it tonight and see if I can get it a little better. Makes sense that the tip would stop feeding if the wire stopped moving at the rollers. Thanks again, I really appreciate the help. Bob
Reply:Hang in there . . . you CAN weld aluminum with a Weld-Pak 155!    From my own experience:On 1/8" material and thicker, you will have to run your MIG at max power (E).Under 1/8" thick, you can use "D", but you will have to be careful to avoid burn through.  It will happen faster than you can say, "Oh crap!"Wire speed will be always be high, I mean in the 8 to 10 range.Keep your ESO, Electrode Stick Out (the distance from the contact tip to the work) longer than you would if welding steel.   I keep the ESO between 1/2" & 3/4" for aluminum.   I'd bet that you're holding the tip too close to the work and that's what is causing the wire to melt in the tip.Keep the torch cable as straight as possible and plan your work to keep it that way.  I zip tie a length of PVC conduit to the torch cable to keep it straighter.Set your drive roller tension loose enough that if you pulled the trigger and stopped the wire with your hand, the drive rollers will slip.If you have it available, 5356 wire will feed much better than 4043.   5356 however will wear out your cable liner sooner.   It solidifies quicker which isn't a bad thing for tack welds.Clean the areas to be welded with a CLEAN stainless steel wire brush.  I keep a dedicated brush for this.   The matte gray coating on the aluminum is aluminum oxide and if you don't remove it first, you'll have to burn through it to get to the base metal.   The problem with doing that is that aluminum oxide melts at twice the temperature of un-oxidized aluminum.   So while you're waiting the few milliseconds for the oxide layer to melt, the base metal underneath is already well past it's melting point and it will disappear before your eyes.Always try to push your welds.   This will keep the bead cleaner and get better penetration.    Keep in mind that while pushing your weld, you still have to watch the puddle BEHIND the arc to guage your progress.Like you, I'm just a hobbiest and can't justify a bigger machine or spool gun.     I've been using both a gas converted Weld-Pak 155 and a Pro-Mig 175 to weld aluminum and believe me, it CAN be done with good results.   Good Luck.There are no small projects
Reply:Dang, I never thought I'd get this much good advice, and this fast. You guys don't have jobs? Or, are you like me and the boss is 400 miles away and oblivious? Seriously, I work for a great company and finally got a few hours downtime(rare), so I am treating myself to a little relaxation welding. 122 hours overtime last month, I needed a break. Thanks for all the input, I'll repost in a few days and let you all know how it's going. Have a safe weekend. Bob
Reply:I have read on other boards upsizing the tip is a good idea for Al.  The Al. will expand more than steel and cuase it to bind in the tip.DennisThermal Arc 185-TSWMillermatic Challenger 172VictorO/AAtlas Craftsman 12 by 24 LatheEsab PCM-875Wholesalem Tool Mill-Drill
Reply:Ok, I drilled out the tip to .050 because the Dealer near me doesn't carry anything that big. Seems to feed a LOT better. Argon is set to 25 psi, tap is at "D', speed is at 8/9, and I am leaning the torch about 30 degrees( pushing foward). Should I be using a flux? Seems I remember we were using a paste flux mixed with water when Uncle Sam was teaching me to weld in '79. Of course that was oxy-acetylene welding on aluminum. I am still getting these bubble gum looking welds, with very little strength. Like little wads of chewing gum. Also, if I try to speed up, the weld gets worse, if I slow down it burns through. Oh, I am welding thin wall 1" square tubing. Electrode is positive as I understand it. The pos(+) lead inside is hooked to the post leading to the gun, not the ground. I am using a stainless steel brush(new) and brushing in one direction only, and then wiping the metal down with acetone. That's all I can think of right now. Oh, here's a tip: Move the rag with the acetone on it FAR away from the welding table!!! Got kind of warm all of a sudden on my bare arm just above where the rag was laying. WooHoo !! Bob
Reply:Got Kinda warm did it?Ah ....um that stuff is pretty darn flammable!LMAO . .......  Thanks for the laughWashman
Reply:Originally Posted by DispenserTechI have a weld-Pak 155 and have used it w/ flux-core for years. No problems. I just bought the kit to upgrade to gas and the kit for aluminum, plus 80 cu bottle Argon. Made all the conversions, and welds look like garbage. Figured out I had to switch polarity. First weld looked good but no strength/ penetration. Subsequent welds are very poor. Tried all different power and speed settings. Wire is bird-nesting repeatedly. I think this is because the tip is getting hot and wire is expanding and jamming in tip. I know for a fact that the wire is hanging up/melting in the tip, and I think this is the birdnesting cause. I am using .035 wire and tip. Should I move up a tip size? Gas is running at 25, inside garage, no wind. Welds appear to havew very little penetration at all, and break very easily. Any input is greatly appreciated. I am not a welder, but Uncle Sam trained me to be about a gajillion years ago, or so it seems. Just a hobbyist now. Thank you.
Reply:also if you are using .035 aluminum wire you will need a .035A tip. The a stands for aluminum and is much larger than the .035 regular tip. Billy