Built up edge

Formation

• the cutting speed is low. This is because at high cutting speeds the metal moving away from the workpiece becomes hot enough to recover before seizing onto the tool, preventing the formation of a BUE.
• the metal being cut is one that work-hardens and is reluctant to recover. A BUE will not form with pure metals since they do not work-harden much. Conversely, alloys, such as steel, do work-harden and recover less so they are prone to forming a BUE.

  Effects on the cutting process

• A reduction in the power demand of the cutting operation.
• Slight increase in tool life, since the cutting is partly being done by the built up edge rather than the tool itself.

• Excessive work hardening at the surface of the workpiece.
• Poor surface finish, since bits of the BUE eventually break off and stick to the workpiece. These bits tend to be problematic since, due to the work-hardening they underwent, they are very hard and so become abrasive.
• A reduction in the dimensional control of the process, due to the dynamically changing geometry of the cutting tool.