Tough Welding

[Seano]

Had a bit of an odd one in the workshop today, was asked to try and sort out a problem that one of the young boys was having, he had to make a bracket from 6mm aly using a T fillet weld, his first problem was trying to weld at 70a using a lorch T 220, 2.4 tip 5/16 shroud and 10lpm gas, the first part was easy set amps about 175, but he was still having problems with cleaning and having black crud in the bead which was pretty scruffy he was having a problem trying to establish a pool so ac balance was upped to 50% but the weld still looked a bit scruffy so gas was upped to 15lpm. A bead was achieved but tungsten was glowing with badly balled end which ended up with a widened bead despite moving at a rapid rste.....so any tig wizards shine any light.

 

[wheresmejumper]

isnt that too much gas?
more amps and less balance would help tungsten.

 

[hotrodder]

Several possible suspects, difficult to say without pics but i'm gonna go with gas too... the bit that jumped out at me was a #5 ceramic @ lots of amps and >10 lpm. While a fillet helps 'trap' the argon a #5 is pretty small for the material/amperage etc and at 10lpm and more could well be pulling in air. Personally i'd be using a #7 or 8 @ around 7 lpm (less at lower amperages), with a gas lens you can reach daft levels of stickout before running into problems i.e. get a better view of the weldpool too

At 50% EN a modern squarewave inverter will normally make a mess of a 2.4mm tungsten above 150A. Should get enough 'cleaning' from the arc at >75% EN at that sort of amperage

 

[backpurge]

I know this is a bit of a daft question but did you wire brush the parts before they were tacked together, if they were cleaned after they were tacked you are not removing the oxide plus any other crap that is on the material faces that are touching (if this makes sense), any contamination will get pulled into the weldpool

Was the joint tight, air can get pulled through gaps and cause problems

Try a bead on plate weld using the same material, if that is OK the problem is with that particular joint set up

Totally agree with all the comments above re gas flows and amperage settings, remember argon is about 1.5 x heavier than air so for welding in the flat position it just falls out of the end of the torch and flows over the weld, you don't need high flow rates, 6 lpm will suffice for the majority of applications

 

[Seano]

isnt that too much gas?
more amps and less balance would help tungsten.

The lad started out with 30% ac balance which is the factory default but this wouldn't even brake the surface, bead run on a piece from the same cutting outcome was the same, all parts well scrubbed with ss brush, joint fit up was std with base of the triangular pad eye cut flush at 90º and butted to the flat base plate of the brkt, gas started out at 7lpm.

 

[matt1978]

Something wrong somewhere I have never had to increase from factory default cleaning to 50%.

Strange one.

What grade material is it?

Is it in AC hard or AC soft in background menu?

 

[wheresmejumper]

The lad started out with 30% ac balance which is the factory default but this wouldn't even brake the surface, bead run on a piece from the same cutting outcome was the same, all parts well scrubbed with ss brush, joint fit up was std with base of the triangular pad eye cut flush at 90º and butted to the flat base plate of the brkt, gas started out at 7lpm.

depending on the overall size of plate.....i would increase amps instead of cleaning to penetrate/pool.a 6mm fillet in aluminium needs a lot of power.if i remember right,i think id be using 200 amps on my tig,even a bit more if doing it quickly

im no wizard though!

 

[Seano]

Something wrong somewhere I have never had to increase from factory default cleaning to 50%.

Strange one.

What grade material is it?

Is it in AC hard or AC soft in background menu?

I am ashamed to say now that I have been pulled out of the workshop i have no idea Matt, just run of the mill std ali, we don't usually use anything this thic,k 3mm is usually or thickest, this was a one off.

AC Hard or AC Soft...Hmmmm to be perfectly honest Matt i never really got into having a good run with the machine before i was pulled out, could you please explain Hard/Soft in AC.

 

[Rrunnach]

A bit of pre-heat would not go amiss too.

 

[pedrobedro]

What flavour tungsten was he using ?

 

[Seano]

What flavour tungsten was he using ?

1.5% lanthanated