Metals have different purity levels

Cooking ore as you find in the world will you metal with a low purity and can not be used in making must machines.
By macing the ore there is not much or no change in the purity of the metal.
By washing the the crushed ore in the ore washer this increase the purity to make the next lot of machine.
By putting in the ore in the thermal centrifuge you get pure dust.
Even though a machine may only require impure metal it can be made with purer metal
Ingot will say how pure they as a percentage and macerating these ingot will give dust of same purity which can be put in thermal centrifuge for purification - less pure metal would give stone dust and tiny piles of dust and more pure metals would just give tiny piles of dust.