Machining of Aluminum and Aluminum Alloys / 763 Machinability ratings of cast aluminum alloys Hardness, HB Hardness, HB Alloy (500 kg load, Machinability Alloy (S00 kg load, designation Temper Casting type 10 mm bali) rating(a) designation Temper Casting type 10 mm bali) Machinablllty rating(a) 208 ..