Matching Pairs GRINDING MACHINESOnline version Types of Mills by Jhony Guillermo Montesinos Cossio 1 High Pressure Roll Mill 2 SAG Mill 3 Rod Mill 4 Ball Mill 5 Autogenous Mill 6 What is a mill? It is a device that breaks solid materials into smaller pieces by grinding, crushing, or cutting. Such comminution is an important unit operation in many processes. It is an acronym for semi-autogenous grinding that also uses grinding balls like a ball mill.