Aluminum Bead.

[Welder99]

Ok heres my ?.when i tig aluminum some times the bead will be nice and shinny.onther times it will be dull in color. any advise as to why. i prep the parts to be welded(.ss,power brush)base metal 6061,ac hi freq.argon 15cfh.tungsten,pure.filler rod 4043 and 5356.

[arcdawg]

im not sure but you could be to HOT, i was always told if you are to hot you BURN the metal, heat input is critical.

when i do stainless i strive for nice shiney rainbow color beads.
i do this by grabing a scrap piece the same thickness and rinning a bead on the scrap first, dialing in the machine before i screw up the piece im working on

try cleaning your filler rod too ! WIPE IT DOWN WITH ACCITONE and or scotchbrite pad cause if there is crap on the filler rod (like oxide) its going to play a roll in your weld,

just my thoughts !!!!

good luck brian

[Welder99]

Brain..thanks for your input.you might be right on the heat.i have been known to push the upper limits on heat.i also agree on cleaning the filler rod.im amased at times when you wipe the rod with a clean rag with acetone how much gunk comes off.thanks again.

[Wheels]

Welder99

I only have my mig aluminum backround to draw from but I an sure it applies to tig also. I can never get my al clean enough with only a hand brush . A designated ss brush on my angle grinder helps get the results I am after. Dont let your pals even know where you keep your good ss brush. We hove had a word or two about this in my garage !

[HAWK]

Welder 99,

Sometimes it's tough to correct a problem without seeing it or being there. Here's how I clean my Al and a couple of other things to check.

Clean Aluminum:

I like the 2" Scotch Brite circular discs with the plastic male threads in the center for pneumatic angle die grinders. I run the red discs. They are farily course and do a better job than a SS brush on a grinder. I use the same Scotch Brite material in 4" x 8" pads to clean the filler rod. Once the discs get full of aluminum grit throw them out.

After the initial cleaning a white cloth with acetone followed by a clean, dry, white cloth work wonders. This applies to base metal and filler rod. If your machine has the ability to adjust your negative balance, play around between 60% and 80%. The number will vary depending on how good a grade of aluminum you have to work with.

You may also be losing your shielding gas. If you tungsten starts degrading, stop welding and prep the end again. I sharpen to a point and then blunt the end even on machines like the Lincoln SquareWave and the Miller Syncrowave. It will ball with the current as you weld on a non inverter machine. Some folks like to ball the end on DCRP and a peice of copper before starting to weld. This technique works especially well on a standard square wave GTAW machine. Just to test drop your CFH to 12 and see what happens. In a still environment I can weld all day at 12CFH pure argon or He/Ar mix without shielding problems. 15CFH may create a turbulence depending on torch position and draw in the atmosphere ruining your nice shiny bead.

[Welder99]

Thanks for the input Hawk.I Have a Lincoln 355 @home in the shop and here @work i use a miller syncrowave 350,both machines compare very close it seems as far as the arc and options.i was going to ask as far as heat goes is there a interpass temp on aluminum?.i was wondering when you mentioned sharping the tungsten to a point then blunt the end then let the machine ball the end of that does that not cut down on the amount of amperage you can run without floating the tungsten out?.also i have a xmt304 with a xr-15 push/pull system i normaly run when i get into 1/4 thick base metal and above.i trim the volts to where i break from the short arc to just inside a spray.this seems to work well.but i do at times seem to get a lot of black surface to the top of the bead.(i can also run the xmt on my trailblazer250).well again thats for the input.

Welder99
ps.sure is nice to have a place to come and chat with others in the same field.(a wealth of information).wish we had it 20 yrs agao.

[HAWK]

Welder99,

Welcome aboard!

I run with the rule that 250-350 degrees farenheit is a suitable interpass temperature for most alloys. Some procedures for critical weldments specify an interpass range. I have seen such written for heat exchangers. However, the interpass range is typically broader than the 100 degree line I use.

Yes the self balling procedure reduces the amperage you can run until the ball forms. That is why I do it this way. Even though I have to increase the tungsten diameter over the norm, I am able to get better arc control from the pointed "flat" than is capable with the ball. I learned this from a older guy who had been welding 46 years. Now that I do most critical TIG with a Dynasty 200DX it is really not applicable except using the HF box on my Trailblazer.

The XR is a killer system. I power it from a 301G Trailblazer. I run the 30' air cooled edge. It is rated 250amps at 60% or 200 at 100%. I figure it does not flinch on 325 amps at 20-30%DC.

I miss my XMT304 and the Optima pulser. Nothing beats a pulsed aluminum spray. I also run right on the verge of spray. There is still a very slight crackle to the arc, but is wanting to spray. The black you speak of is an inherent problem for me and the XR. I think the outdoors wafting away the shielding gas gets me every time.

I am running 1/16" 4043 in the XR and typically break it out for .375 and thicker material. I am a fool for GTAW and 5356 whenever possible. I prefer 4043 in GMAW if applicable, 5356 for GTAW unless ductility and tensile strength are adversely affected.