hello every 1 can some one give me information abt material ( STEEL
STAINLESS STEEL,CAST IRON,NON-FERROUS MATERIAL,HIGH-TEMP ALLOYS,
HARDENED MATERIALS ) haw we know haw hard is and each material hv own Nomber so can some one explaine plz..plz...if i know haw hard than is easy to chose speed & feed ...is there n e side that i can visit...