Built up edge
In machining, specifically cutting operations, a built-up edge (BUE) is an accumulation of material against the rake face that seizes to the tool tip, separating it from the chip.
[1] Because shear is strongest at the initial contact surface with the cutting tool, the first layer of metal impacting and seizing on it work-hardens more than the rest of the volume of metal.
The process repeats itself and, after some time, a built up edge (which could be several hundred micrometres thick) forms.
[1] The conditions necessary for a noticeable edge to build up are that: The built up edge effectively changes tool geometry and rake steepness.
It also reduces the contact area between the chip and the cutting tool,[1] leading to: However, the formation of BUEs have negative effects on the quality of the workpiece,[1] specifically:
