Aluminum Oxide is extremely hard and sharp,

and cut even the hardest metals.
                                                                                                                      Aluminum Oxide
It is the most widely used abrasive in blast finishing                                

and surface preparation because of its cost and the  number of times that it can be recycled.

Aluminum oxide does not contain any free silica so it is safer to use than sand and since the grit size is more consistent and cuts much faster than sand it leaves a smoother surface.

Aluminum oxide has many uses, from cleaning engine heads, valves, pistons and turbine blades in the aircraft industry to lettering in monument and marker inscriptions. It is also commonly used for matte finishing, as well as cleaning and preparing parts for metallizing, plating and welding.