Welding Tips and Tricks

Wow this stuff is tricky. This piece is a belt pulley on a lawn tractor. It breaks repeatedly and they are very difficult to find new. We've tried wire, tig and stick and everything tends to just ball up and not wet in at all. I think it has a high magnesium content as the spatter is very bright blue. Any suggestion would be appreciated. This piece was successfully welded before by someone and the crack is beside the previous weld.

Hey there bones.

I've welded a lot of cast aluminium lately, mostly motorcycle parts, with good success using 5356 and giving the parts a really good 'cleaning pass' before lighting up properly to form a puddle. Then clean and clean again.

So much depends on the material which, as you implied, is often something of a mystery.

A friend of mine did a pulley repair awhile ago and completely side-stepped conventional welding. He cleaned/veed the crack really well and then used that HTC type aluminium 'brazing rod'. So the parent material never even melts, you just heat the part with a propane torch and the rod just melts into the crack, as it were.

I laughed at the time but I've since brazed a couple T joints on sheet aluminium with the same rod, then destruction tested them. They were impressively strong! Oh, and the repaired pulley is still holding up just fine.


Kym

A 4027 tig rod would be a good choice for casting aluminium welds. Because of its higher silicon content and for preventing porosity. Silicon is a deoxidizer which lowers the melting point of the aluminum alloys.A lower melting point would allow the filler wire to flow at a lower amperage.