I didn't know that...

[Steve_in_Mich]

I didn't know that aluminum to aluminum could be spot welded like iron containing materials. I took apart a HP keyboard from an instrument yesterday and noticed the aluminum framework/face around the individual keys was a laminate of two sheets of aluminum each about 0.045" in thickness. I tried to separate the plys thinking they must have used a two sided tape to hold register. TUFF stuff, I say to myself as I wedge and twist a screwdriver between the two layers. Then, SNAP and a portion of the sheets come apart. On closer examination I see that they are spot welded together and the spots look like those left by my Miller resistance spotwelder on sheetmetal. This is exciting news to me to think that I can spot weld aluminum sheets together. Now comes the question to you welders (before I actually give it a try), is it a special spotwelder that is required, in a special gas atmosphere and using a special technique OR, have I finally only blindly stumbled across what you all have known forever. Is anybody using the Miller LMSW 52 to weld Al to Al ?

[rklopp]

Might be an ultrasonic weld, rather than an electric spot weld. In ultrasonic welding, the sheets are pinched between rough anvils that vibrate sideways ultrasonically. The anvils grip the sheets but the interface slips back and forth, heating the joint and breaking up the oxide film. Then the ultrasonics stop and the anvils squeeze the joint tight until it fuses. This type of welding is used in high-tech settings partially because of good consmetics--the sheets are not marked up as occurs in an electric spot weld.

[Marty_Escarcega]

It is my understanding that aluminum spot welders are far more specialized and sophisticated than your Miller spot welder.

Marty