In practical situation, the time at which a tool ceases to produce workpieces with desired size, surface quality and acceptable dimensional tolerances, usually determines the end of tool life. Several mechanisms of wear can contributes to the tool life period. The main objective of tool life testing and wear investigation is to determine experimentally how wear affect the useful life of cutting tool. In most cases the tool wears gradually and the work done by the tool becomes less satisfactory. For instance, the roughness of the machined surface becomes too high, cutting forces rise and cause intolerable deflections or vibrations. As the tool wear rate increases, the dimensional tolerances can not be maintained. Various damage and wear of the cutting tool can be developed during cutting process [2]. The various features of turning tool wear, cracks and breakage indicated in Figure 1. There are several different causes and mechanisms of tool wear. Friction on the rake face and on the flank of the tool occurs under a close contact of freshly created surface of the workpiece material. The coolant penetrates into this contact zone only at very low cutting speed. The pressure in the contact zone is at least equal to the yield stress of the workpiece material [1] [2]. The temperatures in the contact zone are high and may reach the melting temperature of the one of the materials in this zone, most often that of the workpiece material.

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