Okimoto Posted May 14, 2006 Share Posted May 14, 2006 I was under the impression that you needed to use AC with aluminum due to the nature of the aluminum having embedded impurities which is assisted in floating up by the alternating current? Quote Link to comment Share on other sites More sharing options...
johnc Posted May 14, 2006 Share Posted May 14, 2006 OK, basic welding 101. Aluminum does not have imbedded impurities. It develops a thin layer of oxide on its surface as oxygen reacts with the surface molecules. This layer of Aluminum Oxide (same stuff they make sandpaper out of) is very hard and melts at a temperature that's over double the melting point of the base aluminum. The oxide layer must be chemically or physically removed PRIOR to welding to get a clean, strong weld. DC Electrode Positive welding with an Argon shield breaks up any remaining oxides ahead of the weld pool and carries them off in the shielding gas. AC welding also breaks up the remaining oxides from the force of the current switching and the time spent Electrode Negative with the oxides deposited on the edge of the weld pool. Quote Link to comment Share on other sites More sharing options...
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