Welding Tips and Tricks

Superb camera work here I loved this episode, very informative. I hadn't considered the effect of frequency on penetration before.
If you think logically about it the bead narrows with increased frequency so you would expect more penetration as a result but the reverse is true!
And what about the back side shot with the scratch mark, what's up with that? It's like the oxide layer on the back side stayed intact as a film and merely stretched out like cling-wrap as the reinforcement penetrated through!

Coldman wrote: And what about the back side shot with the scratch mark, what's up with that? It's like the oxide layer on the back side stayed intact as a film and merely stretched out like cling-wrap as the reinforcement penetrated through!

IMHO that's exacty what's happening. The back is not exposed to the cleaning action of the arc, so the oxide layer is staying intact and it's staying put. As the oxide melting point is so much, much higher than the alu itself it just stays there like a 'skin' over the molten metal when it melts through from the top.

I suspect some of the guys on here who work regularly with anodized alu see this effect even more as the anodization layer is kinda a extra-extra-thick oxide layer on the alu and probably is even more tenacious and stopping anything breaking through on the back.

Bye, Arno.

All I know is that when I get back to school I'm going to get a thick peice of aluminum crank up the hertz as high as it will go and set the pulse to about 10-11 and just slam the pedal down for a couple seconds to see how annoying tig welding can be.