If you could state the problems you are facing it would be easier to let you know some information as required.The main actions taking place in a ball mill are cascading & cateracting actions by balls of differnnt sizes.Mill is lined from inside by liners of Mn steel casting & the grinding ball used in the mill are of Cr steel casting.High Cr casting in first chamber [say 17 to 20%]& lesser Cr in the second chamber[say12 to 15 %]. The mill shell is of BQ quality steel.Other important parts are trunion, its bearing etc. You may be having this information with you. I am sure you are not looking thie type of prelimanary information.Other information may be posted such as hardness requirement etc if required.But please specify your problems/requirement.