Built Up Edge

The method of adhering or welding of microchips or powdered particles present during machining to the rake face of the cutting tool is called built up edge (BUE). During machining operation always there is some amount of micro chips or powdered particles will be produced. Also during machining according to the first law of thermodynamics whatever the energy supplied will be converted into the heat energy and due to this the rake face of the single point cutting tool is experiencing high temperature. When the microchips or powdered particles are moving the rake face of the tool, they will get exposed to high temperature environment and some of the particles may get adhered or welded to the rake face of the tool called as built up edge.

chip with built-up edge

The factors which influencing the formation of built up edge are:

  1. Speed of the machining: During machining with high speed, the time available for adhering microchips will be less and formation of built up edge can be neglected.
  2. Uncut chip thickness: As the uncut chip thickness increases, the force induced during machining will increases which will increases the power consumption and heat generation in machining process, hence the chances of adhering microchips will be increased.
  3. Back rake angle: Reduction in back rake angle will increases the forces in machining and heat generation and hence the chances of formation of BUE will increases.
  4. Use of cutting fluids: During machining operation, if the cutting fluids are used, whatever the heat generated during machining will be carried away by the cutting fluid so that the heat available for adhering will be less and the formation of BUE will be eliminated.

Due to the formation of built up edge the following effects will take place:

  1. Whatever the wear taking place on the rake face, only BUE will get wears out hence the tool life will be increased.
  2. Due to the formation of BUE, the surface finish of the rake of the tool will get damaged and it will increases the friction at the chip tool interface. Forces and power consumption will also increase during machining operation.
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