Welding on Aluminum Castings

Grind off sand from rough castings. Smooth in areas to be welded. There are grinding wheels for 4- 1/2” and larger grinders made specifically to grind aluminum.

Castings that are dirty or oily need special care. You can plasma cut a crack out if possible.This cleans out the oil in the crack. Drill holes at the ends of cracks or they will continue on after the repair is made. Clean the surface with alcohol or similar cleaner. Carefully heat the area with a oxy-acetylene torch to cook out the oil. Go over the crack with the TIG torch with low heat. Use a small tungsten electrode. 

These are called cleanup passes. Do not add welding rod. Every time you go over aluminum it should get cleaner. You will see black discolored aluminum in the beginning. Weld; grind; weld; grind. Eventually the aluminum will be shiny silver color, then you can weld with rod and larger tungsten.

You can use sanding discs on aluminum to metal finish; spray WD40 on the disc and the part to keep it from loading up.