Gradual wear occurs at two principal locations on a cutting tool: the top rake and the nank. Accordingly, two main types of fool wear can he distinguished crater wear and nank we ar. illustrated in Figures 231 and 23.2. We will use a single point toexplain tool wear and the mechanisms that cause it. Crater wear Figure 23 2fa). consists of a cavity in the rake face of the tool that forms and grows from the action of the chip sliding charactenze the Ioo-chip contact against the surface. High stresses and temperatures contributing to the wearing action. The crater can be measured either by its interface, depth or its area Flank wear, Figure 23.2(b). occurs on the nank. or relief face. of the tool. It results from rubbing between the newlygenerated work surfacc and the nank face adjacent to the cutting edge Flank wear is measured by the width of the wear band. This wear hand is sometimes called the nank wear land. Certain features of ank wear can be identified. First. an extreme condition of flank wear often appears on the utting edge at the location corresponding to te onpinal surface of the workpart. This is called notch wear it occurs hecause the original work surface is harder and/or more abrasive than the internal material. which could he caused hy work