[icedvolvo]

Hi,

I have a Thermadyne 186 AC/DC welder and have pretty good success with everything except fillet welds in on Al. I can weld the butts and laps very nicely but have had no success with the fillets. As I have about 70 of these to do I was wondering if someone can suggest some things they might do.

Material : 25 x 25mm x 3mm thick Aluminium box with 25mm x 25mm x 3mm right angle brackets

Machine settings:
Peak 160A/Trough 40A
Pulsed at 1Hz with 70% @ peak : 30% @ trough
AC Freq 120Hz
Electrode Balance set to 70:30 (-ve:+ve)
Pre/Post Flow 1/6sec
2.4mm Zirconated rod, tapered

The problem: As I try to add filler rod into the corner the rod melts and a blob blows off before I can even get it to the pool.

Do I have not not enough stick out or too much? how much stick out and what cup would you use?
Too much/not enough gas flow ? What flow would you use?
Spending too much time, is it all getting too hot ? How long should it take to weld 25mm (1") fillet from start to done?
Which electrode / filler diameter would you use for this?

Thanks for any assistance

[GreinTime]

Try removing some torch angle, I.e make it more straight up and down. I would use 3/32 filler rod (which I think would be 2.4mm, but I can never remember.) You want to have your tungsten pointing directly into the root of the joint, but as I said, try standing the torch up more before adjusting all of your other settings. If your settings work for all of the other joints, then I would try them first and then tweak them from there. With the torch laid down too much you have a lot of the heat being reflected back out of the joint which typically causes premature melting of the filler rod.

[Braehill]

Iced,
If you add filler and move ahead once a second, do the math, once the puddle forms it should take you about 8 to 10 seconds.

I normally use the next size bigger rod on a fillet than I would on a lap joint. Just let the puddle take what it needs to fill out. Add your rod to the vertical member of the joint and let gravity work in your favor.

Sam's right about torch angle, if you tilt it enough to see, it's probably already too much. I normally weld towards myself if possible to be able to see the puddle fill out behind the arc.

Len


Sent from my iPhone using Tapatalk

[MinnesotaDave]

I'm puzzled by the need for pulse with 3mm material?

Set 150-160 amps, no pulse, stick out enough to keep the correct arc length.
Use enough pedal to puddle in 3 seconds or less and get moving.

In general I find fillet welds take more amps than flat and outside corners.

Keep in mind I do not have any adjustments on my machine, 50/50 balance, no pulse, 60hz.

[icedvolvo]

Thanks for all the suggestions people, I will set up and try them today.

Just out of interest when you are doing fillets do you use a bigger cup and rest it on the material so you have a consistent arc length (see quick diagram attached) or do you prop the cup away from the corner? I wondered whether my cup is too close and the argon is too turbulent at the weld site? I know I am grasping at straws here?

[Otto Nobedder]

Another possible issue, which is compounded by torch angle, is gas flow (which isn't listed, so this is guesswork). In a fillet, you have much better gas containment in the joint than a lap joint, for example, so a high gas flow will blow the heat out in the direction the torch is pointed. Even dead-on doesn't split the flow evenly, as one side of the arc has your bead in the way. I would suggest cutting your gas flow by 1/3 to 1/2, depending on where you currently have it set, and aim for as little torch angle as needed to see the arc.

As for stick-out, the gas-trap effect in a fillet allows you a broad range. I like as much as 12mm, to keep the cup out of my view of the puddle, but here, personal preference rules.

@Dave,
While I agree pulse is not required here, it's a feature I've used when the cosmetics of a weld are important. That regular, metronome-like pulse helps me keep a steady even movement and consistent bead width. It can even be a bit hypnotic, which is nice for making time pass on repetitive/tedious work. I can't say if that's the OPs purpose for it, but it's reasonable.

Steve S

[MinnesotaDave]

I don't like to rest the cup on aluminum since it's so soft it tends to drag on the cup.

I normally run a #8 cup with standard collet body, #7 with a gas lens. Stick out enough to hold correct arc length without resting the cup on anything.

Good luck and keep after it

When I was teaching my son, once he got comfortable with using more amps it went much better.

[Otto Nobedder]

As for the last question posted, I prefer a smaller cup and propping away from the weld for aluminum. Again, personal preference, though, as either can work if you're comfortable with it.

The closer the cup is to the weld, the more gas flow can become an issue, so adjust accordingly.

I would also add, that in a fillet or a groove weld on thick material, I find I move quicker dipping the rod. Not exactly stabbing at it, but getting the filler to the puddle quickly to reduce the chance of melt-off.

Let us know if any of these suggestions prove useful. Hearing what does and doesn't work educates us all.

Steve S

[icedvolvo]

I thought I would update people as to what I have found while experimenting with this problem. Please note this may not work for you but I hope some of it helps if you have similar problems.

Note 1: the original problem was that although other welds worked fine I was having a big problem with Aluminium fillet welds with 25x25x3mm brackets to 35x25x3mm box: as I put the filler rod towards the weld a blob of molten Al would blow off the end of the filler rod long before I got anywhere the actual joint or weld pool. Setup was as follows:

Initial Machine settings:
Peak 160A/Trough 40A
Pulsed at 1Hz with 70% @ peak : 30% @ trough
AC Freq 120Hz
Electrode Balance set to 90:10 (-ve:+ve)
Pre/Post Flow 1/6sec
2.4mm Zirconated rod, tapered

Weld look before

b4.jpg (29.53 KiB) Viewed 1257 times

Note 2: I could weld the joint autogenically (i.e. no filler rod) quite nicely but of course strength is the issue with that.

Solutions found:

1: Way too much gas! I assume that because this is in a corner with the cup pointed towards the rod that you need much less gas and hot plasma was hitting the rod well before it got near the pool. I experimented and found that if I dabbed the rod in very quickly at a very low angle i.e. sneaking in along the the corner and quickly dabbing at the very edge of the weld it would work better but this was too unpredictable and too error prone to make it useful. However once I played with the settings and reduced the gas down to <7 l/min this seemed to allow me to get closer with the rod before it melted.

2: Way too much -ve balance. I assumed that as I had new clean Aluminium which I had brushed and acetoned I could safely use almost no cleaning action: RIGHT and WRONG! With autogenic welding with no oxide it worked fine but as soon as the rod "blobbed" it picked up oxide and with no cleaning action the weld wet to crap form then on! So if I used filler rod then I set the balance back to 70:30 or even 65:35. This allowed me to stuff up without dirtying the weld!

3: Pulsing! For me pulsing seems to work when I have a good flat position and can move from beginning to end in a smooth motion without stopping. However many of these joints were in non ideal positions so I turned off pulsing and immediately had better results. However I was having some problems getting to hot so I set the "down slope" to about 2 seconds and used the trigger to control my own pulsing: if I thought the pool was too hot or I needed to reposition release the trigger readjust/cool and then pull the trigger again.

4: I had originally been using 2.4mm filler rods but you need to use a bigger filler rod! Using a 3.2mm rod worked much better and I could sort of just dab the rod in and not have to push it in to get enough filler material.

However I still did not get the results I was after so I resorted to cheating!

5: In the end I got the best results by doing a quick 3 pass run yeah I know time consuming but it gave the best results:
Pass 1: autogenic pass: just weld the two surfaces together
Pass 2: lay filler rod into the corner and run the torch reasonably quickly along the joint to melt the rod into the joint
Pass 3: go back over the weld using the "manual pulsing" to really weld to fillet together being careful not to get it all too hot as the whole thing can just collapse. In fact you can even do this 3rd pass much later after doing all the 1/2 passes.

after making changes

aft.jpg (40.62 KiB) Viewed 1257 times

PS: A warning for those who use acetone; I was wiping the rods and material with a acetone soaked cloth and during the process of wetting the cloth managed to soak my glove in it! Now good sense should tell you don't start welding until your glove has dried out .... well as I started welding the remaining acetone caught fire in my glove and it started to get hotter and hotter but with the helmet on I could not see the flame .... and then it got very very hot .....I think theres a lesson in there somewhere!

[Braehill]

Iced,
Isn't amazing how good hot gloves are at teaching, and usually in a single lesson. My kids will tell you that my favorite saying is 'Stupid's supposed to hurt, it keeps you from doing it again".

There's no such thing as cheating when it comes to welding, if it works, it's all good. The welds look much better. Glad you figured it out.

Len

[steeldr.]

not sure,but I think if acetone fumes come in contact with your weld arc, it produces phosgene gas,(deadly). Also, try welding al. using DC STRAIGHT POLARITY and 100% helium for a shielding gas,and a pointed 2% thoriated tungsten if you have the equipment to do so....hope this helps.....ron . PS. acetone is absorbed through the skin and can kidney damage and other problems.

[Drifta-X]

^^^^^ um ac for al unless u are some sort of tig welding guru

[GreinTime]

I'm pretty positive that is chlorinated aerosols specifically that produce phosgene gas. That being said, welding without making sure that the surface is clean of chemical contaminants is generally a bad practice

[TRACKRANGER]

I would add the following
1: get yourself as comfortable as possible
2: pull the filler rod further away from the arc while not actually applying/dipping filler (keep the rod cooler)
3: possibly hold the rod further 'in' along its length (give yourself more stability to keep the rod steady)
4: keep the rod angle as low as possible
5: make sure the filler rod is really clean (e.g. use stainless-steel wool)
6: maybe consider less of a point on the tungsten for aluminum work

My 2 cents, but YMMV

[bcrx7]

Not sure if it was mentioned or if you have done this already, make sure you clean your filler rods as well very well and of course your rod hand glove is clean! Any oil on there will not be good!

[Deepak]

I'm pretty positive that is chlorinated aerosols specifically that produce phosgene gas. That being said, welding without making sure that the surface is clean of chemical contaminants is generally a bad practice

Actually any chlorinated compound could potentially create phosgene so be sure to read your labels twice and be aware of potential airborne contaminants.

The best bet is to use acetone or MEK since they're both volatile (quick evaporating) hydrocarbons (no Cl!). A quick read of the MSDS sheets will show that as long as accumulated vapors aren't suffocating you, that they're relatively harmless. In a pinch toluene or xylene could be used, but these chemicals do have toxic effects so a respirator that's rated for organic vapors should be used in conjunction.

[Otto Nobedder]

Here we go again, on the surgical cleaning of aluminum. Clean the filler rod? Really? Are you welding the space shuttle?

PLEASE practice welding dirty aluminum. It can be done. Just wire-wheel the surface bulls$%t off, and BLAZE it in, like TamJeff welds anodized. The crap WILL come to the top, when you get it right.

When you can weld "dirty" aluminum comfortably, you can weld damn near anything.

Steve S

[TRACKRANGER]

Here we go again, on the surgical cleaning of aluminum. Clean the filler rod? Really? Are you welding the space shuttle?

Steve S

Steve, thanks for your comments. But nobody mentioned surgical, just clean. Just trying to help the O/P with some helpful tips.

[Superiorwelding]

Here we go again, on the surgical cleaning of aluminum. Clean the filler rod? Really? Are you welding the space shuttle?

Steve S

Steve, thanks for your comments. But nobody mentioned surgical, just clean. Just trying to help the O/P with some helpful tips.

The problem lies with those (not necessarily you) that over emphasize the need to wipe everything down and clean it to a inch of its life. In the real world of welding alum, this is either not allowed per time constraints or not necessary at all. There are applications where alum might need cleaned this well but not in real life. Look up the fuel tank I posted here. All that was done was a wire brush (not done by me) and I went to town. Fuel tanks are a prime example of a real world situation welding aluminum.
-Jonathan

Edit; for your consideration.
http://forum.weldingtipsandtricks.com/v ... f=5&t=5544
http://forum.weldingtipsandtricks.com/v ... f=5&t=5594

[TRACKRANGER]

Here we go again, on the surgical cleaning of aluminum. Clean the filler rod? Really? Are you welding the space shuttle?

Steve S

Steve, thanks for your comments. But nobody mentioned surgical, just clean. Just trying to help the O/P with some helpful tips.

The problem lies with those (not necessarily you) that over emphasize the need to wipe everything down and clean it to a inch of its life. In the real world of welding alum, this is either not allowed per time constraints or not necessary at all. There are applications where alum might need cleaned this well but not in real life. Look up the fuel tank I posted here. All that was done was a wire brush (not done by me) and I went to town. Fuel tanks are a prime example of a real world situation welding aluminum.
-Jonathan

Edit; for your consideration.
http://forum.weldingtipsandtricks.com/v ... f=5&t=5544
http://forum.weldingtipsandtricks.com/v ... f=5&t=5594

All Good points above.

My only comment is that adding clean filler means the new weld bead material is clean, and as long as it will bond with the parent metal OK, you get a good weld. If the filler has impurities, then those impurities are going to wind up in that bead, and the finish ain't likely to be so good. Not rocket science.

I don't know what the O/P's rods were like, he didn't say. But the picture of the first weld sure showed that there was some gunk in there. Maybe it came from the rods?

If you had used an uncleaned aluminium strip cut from that tank as the filler material, would you have expected to get that same nice quality of finish in the bead? (I know I wouldn't be able to, but that of course might not apply to everyone)

I definitely agree that if the rods are stored and handled properly, then there's no need to clean. Just go ahead and start welding. No offense meant or taken.