Types of Tool Wear - Flank wear, Crater wear, Corner wear
Tool wear is the inevitable cause tool failure in the machining process. The extent of tool wear has a strong influence on dimensional accuracy and surface finish obtained. The gradual wear of the tool occurs at three principal locations of a cutting tool. According to this cutting tool wear is classified into
Flank wearIt is due to work hardening. Flank wear occurs at the tool flanks, where it contacts with the finished surface, as a result of abrasion and adhesion wear. The cutting force increases with flank wear. It affects the great extent of mechanics of cutting. The flank wear region is known as wear land and is measured by the width of wear land. If the width of wear land exceeds 0.5-0.6mm the excessive cutting forces cause tool failure.
Crater wearCrater wear happens on the tool face at a short distance from cutting edge by the action of chip flow over the face at very high temperature. The crater wear is mainly due to diffusion and abrasion. They are commonly observed where the continuous chip is formed (usually in the ductile material). In the brittle material, the chip formation in the shape of a small segment, this loosely fragmented chip has low abrasive action on the face as compared to the continuous chip formation. The depth of crater measures the crater wear; the surface measuring instrument can measure it. The cutting edge may break from tool due to excessive cratering.
Corner wear (nose wear)It occurs at tool nose radius. Corner wear shortens the cutting tool, cause a significant dimensional error in machining. It is considered as part of flank wear since there is no distinguishing boundary between them.
- Flank wear is predominant in low-speed cutting.
- The crater is predominant in high-speed cutting.