Aluminium corner weld

[Bruce]

Now you see, this is what does my head in. I wanted to practice some inside corner welds. So on with the size 4 ceramic and pulled the tungsten out a bit more and lit the HF fires.

Got a nice arc and started creating a weld pool on one piece and started to stitch down to the second. Suddenly the arc flips to this second piece leaving just this tiny gap between two weld pools.
The weld looks wonderful. I'd put pictures up and you'd all stroke my ego at what a good looking weld it was, but twist the metal a bit vigourously and it will break along the filler . i.e. two seperate weld pools with good penetration only held together by the filler.

How do I get the arc to cleanly transit between the two pieces to actually weld them together rather than glue them together with filler? Is this where the lack of pulse comes into it?

 

[fingers99]

AC or DC?

 

[Bruce]

AC


I dont need a slap THAT badly

 

[fingers99]

In asked 'cos -- neatness of weld aside -- it's one of the issues with DC ally TIG.

More amps, maybe, or different rod. If you lay down a bead on a practice peice with your settings, what's the penetration like?

 

[hotrodder]

Lack of fusion at the root is a common one with aluminium fillet welds

What you really want is one weld pool before you add filler. Excessive arc length could be one of the reasons why you have 2 weld pools that refuse to join, or may just a bit more juice needed. On thin material the line between one weld pool at the root and a hole is pretty fine

If it is thin(ish) sheet then it's sometimes easier to get the two pools 'bridged' with some filler before melting in deeper

With fusion to/beyond the root the weld should be stronger than the HAZ but 5356 filler is significantly stronger AND more ductile than 4043

Pulse has nothing to do with it at all. If your machine has adjustable AC frequency then higher frequencies tighten the arc cone- improve arc focus and stiffness making it easier to get a pool formed at the root of the two pieces

 

[Bruce]

Lack of fusion at the root is a common one with aluminium fillet welds

What you really want is one weld pool before you add filler. Excessive arc length could be one of the reasons why you have 2 weld pools that refuse to join, or may just a bit more juice needed. On thin material the line between one weld pool at the root and a hole is pretty fine

If it is thin(ish) sheet then it's sometimes easier to get the two pools 'bridged' with some filler before melting in deeper

With fusion to/beyond the root the weld should be stronger than the HAZ but 5356 filler is significantly stronger AND more ductile than 4043

Pulse has nothing to do with it at all. If your machine has adjustable AC frequency then higher frequencies tighten the arc cone- improve arc focus and stiffness making it easier to get a pool formed at the root of the two pieces

.

Just to be sure, can you define AC frequency. I would assume that would be 50 Hz. My unit does have a AC wave balance control, is that what you are refering too?

 

[Wozzaaah]

I'm pretty sure that's the one Bruce, my Miller doesn't have one but I gather you adjust it one way for better cleaning and the other way for better penetration. I'm watching this thread intently as I'm also struggling with the same problem, those arch covers I welded up for my pickup had reasonable looking welds but not a lot of penetration. As they are mostly cosmetic it's not an issue but I'd like to know where I went wrong.

 

[shenion]

.

Just to be sure, can you define AC frequency. I would assume that would be 50 Hz. My unit does have a AC wave balance control, is that what you are refering too?

An inverter can have an AC frequency setting as it creates the AC from DC. A transformer TIG will not as you can't change the frequency of the power coming in.

On thin metal, I did wish i could change the freq on mine. The arc was wide and tended to wander. Higher frequency better focuses the arc.

 

[Bruce]

I'm pretty sure that's the one Bruce, my Miller doesn't have one but I gather you adjust it one way for better cleaning and the other way for better penetration.

Yep, that's the one I was refering to. Normally I have it set to 30 % because I'm quite anal about making sure the surface is properly prepped. I'll try again on 80% and see if it makes a difference.
The arc starts making one helluva buzz-popping sound over 40%. A bit like chucking a teaspoon of water into a hot frying pan of oil. Gives me the willies you see, easier to clean and have a steady hand than be lazy and trembling

 

[hotrodder]

As Shenion said, AC frequency is different to AC balance and only available on inverters. Not necessary by any means but it makes life a little easier. Higher AC frequenies produce a more focused arc with a narrower, slightly deeper weld pool- the arc will still wander around initially until you get a pool formed though

Balance varies the amount of 'cleaning'. With AC the tungstens polarity is constantly switching. When it's negative (EN) more heat is put into the work and during the EP phase the oxide is 'moved out of the way' (to do with electron flow, proton bombardment, cathodic cleaning or something. Witchcraft of some sort anyway)

Too much EN results in a sluggish weld pool (often with 'bits' in it) unless pre weld cleaning is a bit OCD. Too much EP gives the tungsten a hard time.

Bruce, you think your sets loud, AC at 150Hz really sings (ear plugs not a luxury!)

Wozzaaah, if the welds were clean you probably just weren't hot enough. The puddle gets VERY shiney and sinks slightly when you're close to complete penetration (just before the whole thing collapses of course!). You need to feed some filler into the puddle rather than just touching it (as with steel say). Not the easiest thing (for me anyway) to explain but i hope that helps a bit

 

[Bruce]

ahh. Thanks for that. You are very good at explaining

As I only have AC balance, what else (tip and trick) can I do to ease my problem if anything at all?

I'll try the shorter arc , I'm normally about 5-8 mm from tungsten to surface, and root about to see if there is a smaller ceramic to facilitate getting in as close to the corner as possible. (I see lots of touch downs )

BTW. I habitually push the weld with the torch. I find in this cramped type of joint that pulling would be easier. Are there any issues to pulling the weld bead, because when I tried it seemed to pile up the filler behind the arc travel(i.e the filler side) in a raised seam, instead of the usual pushing the filler along with the weld pool and slightly in back and sides of it to create the fish scale effect. I'm not explaining that very well Basically when I pull I get the hump

 

[Wozzaaah]

You've explained it perfectly! I was just 'dapping' the filler into the pool not pushing it in.
I have trouble concentrating on feeding the rod through my fingers so 'dapping' the filler made it a bit easier for me. I'll have another go at a few joins and see what happens.

 

[Bruce]

You've explained it perfectly! I was just 'dapping' the filler into the pool not pushing it in.
I have trouble concentrating on feeding the rod through my fingers so 'dapping' the filler made it a bit easier for me. I'll have another go at a few joins and see what happens.

Me too.

" One, two, three, four, dab that filler weld some more. "

I have to chant or I forget my rhythm. and to breathe

 

[hotrodder]

Bruce,
Your arc length is waaaay too long. An arc length no longer than the diameter of the tungsten is a good guide for DC welding, a little longer for AC is okay. As arc length increases, focus decreases- you heat a larger area than you want to.

Extend the tungsten so you can reach with a larger cup- i use a gas lens whenever possible (better shielding) but they don't react well to burying the tungsten in the weldpool...

Pulling the pool... you're more likely to get 'cold lap' and other LOF issues as the heat is directed at the already deposited filler rather than the joint. Position yourself to the side a bit so you get a good view of the weld and block the part up off the table so your hands or elbows have somewhere to rest

Don't worry about 'the look', lots of bad (exagerated 'dimes') examples about- concentrate on getting sound welds for now. Once the basics are down it's easy to tweak appearences with the way filler is added


Wozzaaah,
I'm not great at feeding filler either but it can become less 'brain intensive' if your willing to suffer a little abuse from the missus- perfect time to practice the motion is in front of the telly of an evening. Just don't poke her in the eye

 

[Bruce]

Thank you

My arc length too long? Heck, I dont know if I have the dexterity to get 2-3mm from the deck without touchdown or welding the tungsten to the filler rod. That torch is a bit unwieldy what with the hose and all the gubbins. Tig welders must have an increadibly steady hand..or do they use a dolly?

Bruce,
Your arc length is waaaay too long. An arc length no longer than the diameter of the tungsten is a good guide for DC welding, a little longer for AC is okay. As arc length increases, focus decreases- you heat a larger area than you want to.

Extend the tungsten so you can reach with a larger cup- i use a gas lens whenever possible (better shielding) but they don't react well to burying the tungsten in the weldpool...

Pulling the pool... you're more likely to get 'cold lap' and other LOF issues as the heat is directed at the already deposited filler rather than the joint. Position yourself to the side a bit so you get a good view of the weld and block the part up off the table so your hands or elbows have somewhere to rest

Don't worry about 'the look', lots of bad (exagerated 'dimes') examples about- concentrate on getting sound welds for now. Once the basics are down it's easy to tweak appearences with the way filler is added


Wozzaaah,
I'm not great at feeding filler either but it can become less 'brain intensive' if your willing to suffer a little abuse from the missus- perfect time to practice the motion is in front of the telly of an evening. Just don't poke her in the eye

 

[runnach]

:..or do they use a dolly?

A dolly is an integral part of a tig hands kit bag, essential for those long stints working away from home away from missus, plus the sheep feel safer........ahem

 

[Bruce]

........ahem

I see.




and this is something you felt obliged to share with us.





I see






So what do stickwelders carry...wellies?

 

[malcolm]

Bruce - what's up tonight - you are seeming aggressive towards stick welders. (Can't be anything wrong with the sheep - they are common in SA).

SA only won the cricket because it was unusually sunny. We're more used to rain. Wait till the rainy match - we'll have you then.

 

[Country Joe]

Bruce - what's up tonight - you are seeming aggressive towards stick welders. (Can't be anything wrong with the sheep - they are common in SA).

SA only won the cricket because it was unusually sunny. We're more used to rain. Wait till the rainy match - we'll have you then.

And I always thought Cheshire was "up north - not in SA.
Having said that, I was never too good at geography!

 

[Country Joe]

Getting back on topic, now!
I'm watching this thread as closely as Wozz, 'cos these things seem to happen to me too!
So, at least you know you're not alone!
Unfortunately though, I don't have any tips - but I'll try some of those I've read!
Helpful as ever,
CJ