Torch Welding Aluminum

admin

OK... I don't want to have to go out and buy a Tig or spool gun and I really don't have the facilities for Tig.  When tourch welding aluminium, is it permissable to use propane instead of acetelyne due to the lower melting point of aluminium?  And is it the same as welding mild steel?  Plus who here has done this?  Any pointersThanksMiller 225 Bobcat
Reply:Done a lot of torch welding over the years.  Always used Oxy/Acety though.  When you ask if you can use propane, are you considering Propane and Oxygen mix?You can use the same rods one uses for TIG welding.  Little different technique though.  Clean the oxide layer off the rod, AND the aluminum you are going to weld.  A flux has to be used on both the rod and the base metal.  Fluxes usually contain some sort of flouride compound for cleaning.  There are probably others available.  Some low temp Aluminum Brazing alloys use a flux that is also a temperature indicator (tells you when base metal is ready to accept the filler material).Gas welding of aluminum is not like welding steel.  The aluminum does not change colors, and after awhile, you'll become proficient to recognize when the base metal is "ready to weld" and when it's too hot and about to "collapse".Good Luck
Reply:I field welded a lot of aluminum irregation pipe over the years. When aluminum melts, the surface of the puddle will form a slight crinkled look. If you don't start moving with your weld right then you will find a hole where the crinkled spot was an instant before.Aluminum has no strength at all when molten. Aluminum melts well below the red spectrum so gives off no infrared rays and of course A/O welding doesn't produce ultraviolet light so all you need is a lens that absorbs the flare of the flux and allows you to see your weld.Never tried welding with propane. Although it will get hot enough for aluminum I don't know if you would have good enough control to produce a decent weld.
Reply:oxygen/propane works IMHO even better than a/o as it is slower to heat so there is less of a chance for the puddle to fall through and it gets well above the melting point. I have found that a backing plate really helps when using a torch on al. Not sure if you can still find them but there used to be rods with the flux on them for brazing al.