Factors Affecting Tool Life

The life of tool is affected by many factors such as: cutting speed, depth of cut, chip thickness, tool geometry, material or the cutting fluid and rigidity of machine. Physical and chemical properties of work material influence tool life by affecting form stability and rate of wear of tools. The nose radius tends to affect tool life.

1. Cutting speed: Cutting speed has the greatest influence on tool life. As the cutting speed increases the temperature also rises. The heat is more concentrated on the tool than on the work and the hardness of the tool metrix changes so the relative increase in the hardness of the work accelerates the abrasive action. The criterion of the wear is dependent on the cutting speed because the predominant wear may be wear for flank or crater if cutting speed is increased.

2. Feed and depth of cut: The tool life is influenced by the feed rate also. With a fine feed the area of chip passing over the tool face is greater than that of coarse feed for a given volume of swarf removal, but to offset this chip will be greater hence the resultant pressure will nullify the advantage.

3. Tool Geometry: The tool life is also affected by tool geometry. A tool with large rake angle becomes weak as a large rake reduces the tool cross-section and the amount of metal to absorb the heat.

4. Tool material: Physical and chemical properties of work material influence tool life by affecting form stability and rate of wear of tool.

5. Cutting fluid: It reduces the coefficient of friction at the chip tool interface and increases tool life.