TIG on Cast Aluminum - All fine until I add Filler

[Fix Until Broke]

Ok - this is baffling me so I'm hoping someone can help point me in the right direction.

Cast Aluminum intake Manifold plate - welding 3/8" diameter holes shut
1.5% Thoriated 3/32 Tungsten, Lincoln TIGRunner 185 biased toward cleaning, 17 series torch, 100% argon at ~20CFH.

I can get a perfect shiny puddle, walk it anywhere I want, over and over again, but as soon as I touch the filler in the puddle (4043 1/16") it's just like I dipped the tungsten. Big "pop" grey soot everywhere, contaminated tungsten, etc. Clean everything up, grind out the weld, remelt a perfect puddle and the same thing happens. I repeat this a couple times and figure that I must have contaminated filler. Get a new stick, clean with scotchbrite and contact cleaner (all I had), no change.

So here's the weird thing - I have 15 holes to weld - this only started happening on the last 2-3 holes.

Just to make it even more interesting, 2 weeks later, in another state, another welder (Miller Synchrowave 250DX), 70% argon/30% HE, 1.5% Lanthinated tungsten, different cast aluminum part (oilpan this time), 4043 filler from a different batch presumably, same issue. I can get a nice puddle, walk it around (boil out any contaminants from the cast), all is well until I touch the filler in the puddle.

The three things that I've been able to deduce with this so far are

1) I'm doing something wrong
2) Both cases this happened suddenly after good welding
3) Both cases I was eventually able to get OK welds, but it took hours of work repeating until something changed and I could add filler again.

I think that sometimes (maybe all the time?) the arc jumps to the filler instead of down to the work piece. I did have back side the filler touching the work piece a few times which made a little more sense as to why the arc would jump to the filler, but after correcting this, I still had the same problem.

I'm no expert welder, but I've got ~100 hours TIG welding aluminum (half of it cast aluminum) so this isn't the first time I've picked up a torch either.

Any help or suggestions are greatly appreciated!

[dave powelson]

pop goes the filler?

Ok - this is baffling me so I'm hoping someone can help point me in the right direction.


The three things that I've been able to deduce with this so far are

1) I'm doing something wrong
2) Both cases this happened suddenly after good welding
3) Both cases I was eventually able to get OK welds, but it took hours of work repeating until something changed and I could add filler again.

I think that sometimes (maybe all the time?) the arc jumps to the filler instead of down to the work piece. I did have back side the filler touching the work piece a few times which made a little more sense as to why the arc would jump to the filler, but after correcting this, I still had the same problem.

I'm no expert welder, but I've got ~100 hours TIG welding aluminum (half of it cast aluminum) so this isn't the first time I've picked up a torch either.

Any help or suggestions are greatly appreciated!

Without any pics or better description of the hole depth, blind/open, etc.
you may have answered your own question.

Crank balance for more pen. Hopefully the tungsten point is still pointed,
if it is, that's good--the point has everything to do with focusing that arc,
making it stiffer and not wander.
On that 175 machine, it needs to be cranked up pretty high to give heavy
AL castings the heat input required for wetout and fusion. Dwell and play
torch around slightly, to keep ramping up local heat in the AL before making
puddle. You need to see some parent casting glints of melt--signaling that
you're approaching some good heat soak--prior to making any filler puddle.
This could take some time with a small machine--it's not several seconds.

[ja baudin]

My first thought is that as your closing up the holes, your casting is heating up and blowing atmosphere out of the holes your trying to close. Ie, it's blowing your argon away. This scenario alway gets worse the closer you get to closing up an air tight space. It is very frustrating, I always have trouble doing it. Allow your part to completely cool, purge chamber with argon, then sew it up fast!!

The other thing, try a larger filler 3/32. You may be heating the smaller one up too fast and blowing it away.

Just my thoughts, I'm not a professional. Good luck

ja

[4given]

Maybe?

I'm just a newbie so I'm not a pro but did you try preheating the manifold especially the holes your filling in? I did a little 3 corner rock hole in a four wheeler differential I had to get all the saturated gear oil out of the cast aluminum near the weld. I preheated it and you could see the oil cooking out of the cast. Soon as it got good and hot and the majority of the oil had migrated away the weld starting puddling in good.

[shovelon]

Ja Baudin suggested bigger filler which is what I was going to suggest. Cast is a very dirty metal, and oil/fuel soaked makes it worse. Most times reaming the hole can help remove surface contamination, but in my experience weld, clean, weld, clean, and continue to do so until the crap is boiled out and the contamination is neutralized with clean fresh weld rod.

Welcome to cast alum.

[Fix Until Broke]

Thanks for all the replies, I appreciate it.

Let's take the intake manifold plate for discussion first...It's for a 4.6L Ford 32 Valve V8 - it's 3" tall, ~1" thick and ~20" long and goes between the intake manifold and the cylinder head. It used to have the flaps in the intake runners that switch which runner is being used and I'm welding those holes shut that the rod ran through for those flaps. Hole is ~3/8" in diameter and ~3/8" deep and is a through hole. I'll see if I can get a picture to reference. I'm welding in the horizontal position with a slight (20deg) angle, the hole axis is ~vertical, the part is clamped in a vice, the ground clamp is on the part itself.

I've done the welding (with no filler) around the hole to boil out any contaminants. Weld, clean, weld, clean, etc. The material is clean enough that I can make a nice clean shiny puddle anywhere around the hole for as long as I want. Just to be sure I went around one of the holes 10 times to be sure there was nothing in the cast material causing the issue. So at this point the part is plenty hot (preheated). The material around the hole is clean, but I brush it (stainless brush) again. Strike up an arc, have a beautiful shiny puddle, walk it around a bit, all is well. As soon as I touch the filler to the puddle, it blows up on me.

The tungsten is balled up on the end due to the high cleaning % I was running. I will try re-sharpening it and running more penetration % after I'm sure the part is clean. I've got plenty of power available from the welder, the part is not that big/thick and is a few hundred degrees after the cleaning.

The strangest part is that it happens suddenly. I'll be welding a hole shut and everything is going well, filler is going in, holes are closing up - no problems. I run out of filler or have to re-position so I stop the weld, re-start, shiny puddle, etc and then as soon as I go to add filler either the arc jumps to the filler or the puddle blows up as soon as the filler touches it.

i've cleaned the filler with scotch brite and solvent, nipped the end off, etc.

I'll report back after trying the higher penetration % and a sharp tungsten and see if that helps.

Thanks again for the comments/suggestions. Keep them coming, I appreciate it!

[Fix Until Broke]

Well, it's probably not the equipment - I used the same welder as I used on the intake manifold to weld a handle on a scraper (aluminum) 3/16" aluminum scraper with a 1.5" OD x 0.040" wall handle and it was just fine. Same filler, same welder, same tungsten, same gas, same me . I was using a 1/8" tungsten, pointed and it ended up with a small ball on the end (maybe 0.040") so the arc was much more focused - maybe that's the key (I just need a 1/4" tungsten for my 20 series torch HA! )

Well, at least I know that I can still TIG weld aluminum. Next weekend, hopefully I'll get the chance to try the intake manifold plate on my other welder (and try the pointed tungsten, higher penetration)

[OscarJr]

It used to have the flaps in the intake runners that switch which runner is being used and I'm welding those holes shut that the rod ran through for those flaps.

That sounds too much like the FR500 intake manifold that was used on the FR500 mustang race car. IF so, that thing is magnesium, not aluminum.

Unless that is the Aviator intake, in which case it would be aluminum. Care to disclose some pictures. They would REALLY help [you] out.

...or, it wouldn't happen to look like this would it:

[Fix Until Broke]

I'm reasonably sure it's aluminum - I was able to weld half of the holes with minimal issues (except for my own mistakes like dipping the tungsten, etc). Strangely, the welding was getting easier the more of them I did, then suddenly went to crap.

I'm not sure how to post pictures, but if you google images of Ford IMCR Weld, it's got pairs of oval and rectangular ports. It does not look like the picture you posted (similar, but not same).

[Fix Until Broke]

Looks like pictures are pretty easy

Here's the other part that welded fine for about 1/3 of the perimeter, then went to crap as well

[OscarJr]

Ah I see now, yup, IMRC plates from the 93-98 Lincoln Mark VIII/96-98 Cobra 32V. I've got cylinder heads that mate up to that intake---building up some longtube headers for some people. Anyways, hope you get that issue figured out. Looks like you have a blower/IC manifold in the background.

Almost sounds like you may be getting an oxygen leak into the argon hose when things get heated up.

[Fix Until Broke]

No, that's just a random picture off the internet. Now that you mention it, the guy I'm welding it up for said it's from/for a Cobra.

[Country Metals]

How old is your welding rods? I had this issue to a while ago, I switched rods from 4043 to 5356- joint wasn't that critical and it welded perfectly. I am guessing after that someone left my rods out and they didn't have black on them but probably has something on it that acetone didn't remove.

Also, make sure you don't leave the argon has shielding with your rod. If you poke too fast you can drag air behind it and that can cause the same problem.

[Fix Until Broke]

The 4043 filler is old (years), but I pull it through a new scotch brite pad until it pulls hard all the way through (surface oxide layer removed), then clean with contact cleaner.

I'm using a #8 gas lens/cup and ~20 SCFH argon (or argon helium on the other welder).

I'll keep better tabs on how far out I'm pulling the filler as well.

Thanks for your input

[Fix Until Broke]

Update

Ok - I welded up the other IMRC plate this weekend on my Miller Syncrowave 250DX and paid close attention to what was going on.

100% argon at ~15CFH, 3/32" Lanthinated tungsten pointed, gas lens with #7 cup, 4043 filler, 50/50 AC balance.

Generally it welded up exceptionally well for cast aluminum, however there were a few struggles.

I think the root of the problem is a wandering arc. I had to bring my filler in almost perpendicular to the tungsten at the very base of the arc to keep it from jumping to the filler. If I brought the filler in at ~45 degrees, the arc would jump to the filler every time and "Poof" it melts the filler well outside the shielding gas. I played around with it and could get a 3" long arc coming out the side of the tungsten.

There were 18 holes to weld, the first 16 went very well (even with my playing around with the filler/arc/etc). The last two fought me with the jumping arc, then contaminated puddle, etc.

I ended up dipping the tungsten a couple times in the process, and ground a point back on each time as well as cleaned up the OD of the tungsten (grinding axially). I wonder if the grooves from the grinding wheel on the OD of the tungsten are causing the arc to want to jump off the side of the tungsten instead of focusing down to the tip? Or maybe I didn't get the tungsten all cleaned up? I'm just using a 4" angle grinder with a standard abrasive steel grinding wheel (new) to dress my tungsten. It works fine for steel welding, but I wonder if on aluminum and continuous high frequency AC that it's more sensitive to the surface finish of the tungsten or something.

What I didn't think of to try was a new piece of tungsten. I did switch to a used piece of pure tungsten in 1/8" just to see if it would help, but it didn't (it also had grind marks on the OD so not the best comparison).

Next time I'm at the welder (maybe this weekend again) I'll grab that same 3/32 tungsten with the grind marks and see if the arc is still jumping out the side and then replace it with a new tungsten and see if I still have the same problem.

Any other suggestions or ideas to try or what may be happening is welcome