Aluminum loads a grinding wheel almost immediately: it is soft and it smears into the pores rather than abrading away. Within seconds the wheel is glazed with metal, it stops cutting, and it starts heating.
A loaded wheel is also a damaged one. The embedded aluminum expands with heat inside the bond, and that is a recognized cause of wheels bursting. Bonded abrasive wheels intended for aluminum exist and are formulated openly for it; a general-purpose grey wheel is not one of them.
The questions welders ask
What about magnesium?
Never. Magnesium dust and fine swarf ignite readily and burn at a temperature water makes worse — a magnesium fire is fed by water rather than extinguished by it. Some castings sold as aluminum are magnesium alloys, which is a reason to identify a casting before taking a grinder to it.
What should I use instead?
A file, a linisher with a fresh belt, or a flap disc used lightly and replaced often. A belt clears itself far better than a bonded wheel because the abrasive is constantly moving away from the contact point, so it is the practical tool for shaping aluminum.
Last reviewed 2026-08-14