This research presents an investigation of the machinability assessment when end milling tool steel (Din 1.2311) BHN 300. The tool steel is a pre-hardened steel and it is widely used for molds or dies in the injection moulding industry. It is also classified as AIS1 grade P20 mold steel. The objective of this assessment is to generate reliable machining data in terms of tool life, cutting force and surface finish in relation to cutting speed, feed rate and depth of cut. During this research, cutting tests were carried by using the both the design of experiment and one-variable-at-a-time experimental techniques. Various cutting tools were used for the different tests including uncoated high speed steel, coated high speed steel, uncoated cemented carbide and coated cemented carbide. The results of these tests were plotted as graphs in order to assess the differences between the different tools. From these machinability assessment tests, a cutting speed, feed rate and depth of cut range for the material can be determined and the optimum cutting conditions chosen, including economic production rate or maximum production rate for the end milling process.