Anodized tube welding

By cncmich Date 03-01-2006 01:57

I've just been looking around researching what I've been doing and all I see is that anodized is impossible to weld... I backfill spot after spot and then go back over and burn in spot after spot and I'll tell ya (got pics to show it) that they end up like a roll of dimes spread just so with a skunk trail up it. The Miller Dynasty helps alot but I'm bad with a Lincoln too. Is this basic welding or is it worth more than 400 a week...

By G.S.Crisi (****)

Date 03-03-2006 19:19

Revision 1: the aluminum oxyde melting temp. has been corrected

Take into account that the chemical composition of the anodized film is aluminum oxyde, a refractory material whose melting point is very high. I don't have the figure on hand at this moment but it is in excess of 2000 Celsius; whereas the aluminum which is under the film melts at 660 Celsius.
Before attempting to weld anodized aluminum you should remove the anodized film by means of sand paper or emery cloth. Don't use a steel brush nor a grinding wheel, aluminum is too soft for them.
Giovanni S. Crisi
Sao Paulo - Brazil

By dringge (*)

Date 03-04-2006 13:03

Does anyone know what the melting point of aluminum oxide is? I find the temperature then lose it again and my memory is not what it used to be. It is a number I should remember as I teach welding and tell students that the oxide layer needs removed because of the high melting point but I cant seem to remember what that temp is.
Thanks

By Lawrence (*****)

Date 03-04-2006 13:48

Aluminum Oxide: Al2O3
Melting Point (°C) 2072
http://www.reade.com/Products/Oxides/aluminum_oxide.html

Aluminum (unalloyed)
Melting Point: 660.37 °C