Abstract
High hardened and/or high strengthened sintered steels are widely used for machine parts because of their high productivity. Sintered products are basically used in operations during which relatively small amount of material is removed, such as finishing, drilling or reaming. This research aims to find out the cutting conditions, appropriate drill geometry and processing method during drilling CrMo low alloy sintered steel with heat treatment, quenching and tempering. The main results obtained are as follows: When the hardened sintered steel was machined using a conventional carbide drill, the drill was received severe friction from an inside surface of hole drilled because of the thermal expansion of the workpiece and the drill generated by cutting heat. In result the drill was broken down after drilling about 20-30 holes according to an excessive cutting torque. However, a newly developed carbide drill having large back taper and appropriate thinning, was be able to drill about 200 holes without severe damage at the cutting speed of 14m/min, feed rate of 0.05mm/rev and using a coolant having high cooling capacity and high lubrication ability.
