Can anyone........(Tig Ali specialist's in particular) give me an amperage clue for welding a vert fillet on 2mm Al, can't seem to get it quite dialled in, either too hot and molten Al is dropping into my cup, or not enough.....
Generally for ali, around 45-50amps per mm will give you a rough setting to play with, so you will want to be around 90-100.
With thinner gauge ali you can't dwell as much as you can on thicker stuff and stainless etc...
The heat transfers very quickly and soon the whole piece is up to temp!
Travel as smoothly as you can, try not to dwell anywhere and keep your rod deposition nice and even. Every dip will cool/freeze the weld pool and stop it from falling away, with thin gauge, the filler rod feed seems to become the most important factor, nice and even.
This weld calculator may help too: http://www.millerwelds.com/resources/calculators/
Although I've found the #s to be a bit off sometimes.
With ali your amps, flat/vert/overhead will be pretty much the same, I weld ali on a day to day basis and if you're having problems it's more likely operator error than anything else.
Practice makes perfect and remember on thin gauge the deposition plays a very big part.
Downhand, vertical, overhead... makes very little difference amperage wise with TIG imo as the amount of filler used is independant of the arc. Only thing that comes to mind (regarding molten Al dripping) is that filler/torch relationships are off a bit- very easy for the arc to melt off the end of the fillerwire which'll result in a mess unless welding downhand
2mm Al... around 90-95A typically for me but it depends on the size of the weldment amongst other things. Maybe a bit lower for a small weldment like a test coupon as there's nowhere for the heat to go
wheelchair, not that i have the slightest clue about welding aluminium. But i have been messing around of late with positional TIG welding on mild steel. I found if i use the pulse function on the machine i certainly get better looking results. Not sure if the machine you use has a pulse function but if it does it may be worth playing around with to see if you can get better results
I doubt pulse will be allowed for test coupons. Some pics may help us see what's going on but won't be as good as getting one of the instructors to watch you. Is it going pear shaped towards the top (as the coupon becomes heat soaked) or just generally? How big are the coupons?
Everything else seems to be ok, so I guess it is a positional thing between cup and rod, will get it sussed in the end..... only two to go..... then I will see if I have passed.... cheers chaps......
Sean, dunno if you can answer this, I am curious as to why C&G stipulates 2mm ali for test???
Ok, so 2mm it is, keep amps low at around 50-60-ish. Assuming vertical up, torch approx 10 degree from 90 , feed filler from top, may take a few to get heat up from initial arc up, but when it gets there, keep chasing the weld till complete. Near to top can be a bugger, if you have slope in/slope out, set this to work to your benefit.
Hi runnach
C&G stipulates 1.5 - 3mm, have been using 3mm up to week before last, last week moved down to 2mm, my choice......... reckon if you can weld thinner material it stands you in good stead for the future, I know it isn't easy but I am willing to persevere also I was using a pedal last week, and while I find it a luxury, we don't have one at work and they are too tight to purchase one, so I better get the hang of sloping out...LoL have got a tee in 3mm and a lap in 2mm in the bin so far only 3 to go, this week I'll go after a butt in 2mm that will leave me with vert tee and pipe on plate, probably in 3mm, strangely I find 2mm easier to work with than 3, thx all for your help and suggestions.....
Ran a quick 2mm vert fillet today to check on amps.
Using 1.6 rod was firing in at around 100, running the majority in at around 70-75 and tailed off to around 50 amps to finish. I was using a foot pedal.
So using a button torch with slope in and out would be looking at main amps @70 and slope amps at 50amps or 70% main dependant on set, with a 1-2 sec slope in and out dependant on preference, you can feather/finger the button to suit the amps needed as you get to the end, you can also run the arc up and down the piece a few times before you start your run to bring it up to temp.
All the best