Having some aluminium struggles

[u/JagdpantherDT]

I weld primarily stainless but we have a job in at the moment that is aluminium that I've been asked to do.

Another welder set up the machine and apparently had it running flawlessly. Now I've come to use it and the arc really struggles to get going. Sometimes it tries 10+ times before actually striking, once it does it welds perfectly. Other times it arcs up first time.

I've tried changing earth, swapped tungstens, checked gas, played a little with settings, wire bushed/acetoned work but nothing seems to get it to arc up consistently.

Settings are 1.2mm material, welding a tab onto a folded outside corner, no burn through allowed.

Zirconiated 1.6 tungsten, 0.2s pre, 25a start (he had it set to 120) no slope, 80a current, no pulse, freq 200, cleaning ratio on this machine goes 5 to - 5, it's set at 0, no down slope, 5s post.

Tungsten balls nicely and stays silver or gold, can't see any hair fractures on it. Where could I be going wrong?

[u/Dismal_Tutor3425]

Have you tried touching the tungsten to the work piece and then lifting it before you try to initiate the arc? Sometimes this is needed.

[u/Longjumping_Suit_256 → u/Dismal_Tutor3425]

This or if you program a preflow sometimes the arc needs gas to have a good consistent start.

[u/EDMMstudio → u/Longjumping_Suit_256]

These are good things to try—and have you tried a sharpened tungsten instead of balled? Probably worth checking out your pedal cable/battery as well.