Mill Headers (Mill Ends) are parts that act as end covers to a tubular type ball mill or rod mill or sag mill. These are conical shaped from the one side that directly gets bolted onto the mill flange and cylindrical shape from the other through which the material inflow or discharge takes place. Mill headers are generally made from castings of various alloy and carbon steels or ductile iron or sometimes they are fabricated in case of light of medium weight designs. A mill header basically provides end support to the mill. They rotate on specially designed trunnion bearings as the cylindrical portion of the header slides on a self-lubricating white metal lining attached to the trunnion. The size of the mill headers depend upon the size of the mills. The bigger the diameter of the mill the larger is the bigger diameter of the cone. Mill headers (mill ends) are also lined with special wear resistant steels from the inside through bolts that rest on the conical portion. These are specially designs bolts that rest on the cone to hold the liners against the header cone. Mill Headers rest on trunnion bearings made of white metals or phosphorous bronze cast or lined over specially designed sockets. The design is such that the lining can be retrofitted or relined on the sockets for faster and more economical replacement.