Thread: Aluminium welding techniques

I am a boilermaker working primarily with Aluminium and it sounds to me like you have got it covered pretty well. Run your power as high as you can without burn through and go like the clappers. Nothing much changes.

I started ally mig at tech today and that was the method taught to us.

My problem is getting the weld to stick at the start, broke a few welds that the bead just fell off.

Did the bead look like it had washed in?
It is common for the bead to perhaps not fuse as well at the start due to the oxide layer, but for the whole bead to not fuse sounds to me like too lower power.
Can you post a picture of the welds?

sorry, it wasn't the whole weld that didn't stick only the start 10-15mm or so. Was using a fronius mig with torch control. Best results came with a starting amps of 205 then backing of one click every couple of pauses. Ended up at around 175A by the end of 200mm or so weld.

Thanks Karl

I have backed off the power a fraction and welding with a standard smooth travel technique. Finding the exact pace is a little tricky, but this is giving me the tidiest results with a reasonably small fillet.

Ben, it sounds like you have a cold starting problem. Are you welding extruded section or soft plate? It does make a difference.

Hard extruded stuff usually requires significantly higher power to punch through the surface, especially at the start. Don't forget to make sure the plate is clean first.

One way is to start the arc ahead of the start point and quickly retreat to the start point and weld from there. Hopefully this would have warmed things up a bit.

One door I make is 6mm plate and a 40 x 10 extruded flat bar reinforcing stitch welded on edge. This needs 50% more power to weld.

Thanks for that. I was supposed to be at tech today to get back into it but had to look after sick kids - hopefully next week!

Yes it is extruded bar, I can get hold of some plate to try too though.

Originally Posted by The_Fixer

Ben, it sounds like you have a cold starting problem. Are you welding extruded section or soft plate? It does make a difference.

Hard extruded stuff usually requires significantly higher power to punch through the surface, especially at the start. Don't forget to make sure the plate is clean first.

One way is to start the arc ahead of the start point and quickly retreat to the start point and weld from there. Hopefully this would have warmed things up a bit.

One door I make is 6mm plate and a 40 x 10 extruded flat bar reinforcing stitch welded on edge. This needs 50% more power to weld.

Ok, Started with 2 100x300x5mm plates today, sanded all the surface of both plates with zirc flap disc.

Did a few welds, ended up finding 230 amps was the sweet spot (fronius pulse mig) 0 on arc length, 0 on inductor. Also did the start 30mm from end, run back to start and make full weld. No fusion failures the last weld I did didn't break, just the plate bent Also did a vertical up, came out awesom - I reckon that is easier than on steel, just rythmic back and forth not really pausing, even looked better than a steel v-up! Thanks for the help, def more confident on ally now - just have to solve the porosity issue I am having!

Keep your nozzle in close Ben and watch the torch angle.

I usualy find about a 10 degree lead angle and about 15mm stick out keeps the weld looking clean and minimal porosity.

Porosity can also happen if the plate is not properly cleaned before welding. Sanding can sometimes actually drive the impurities into the plate. Sand in one direction only and dont keep going back if you can avoid it.

On the coal wagons we used to wipe down with laquer thinners and wire brush with a stainless brush before welding.

Good to hear you're having fun. Most guys tend to avoid the ally like the plague!