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In single point cutting of metals, 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.〔The Open University (UK), 2001. T881 Manufacture Materials Design: Block 2: Cutting, page 14. Milton Keynes: The Open University.〕 ==Formation== Because shear is strongest at the 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. As a consequence of this work hardening, this first layer of metal is stronger than the adjacent metal moving away from the workpiece. Effectively, said first layer becomes part of the tool. The process repeats itself and, after some time, a built up edge (which could be several hundred micrometres thick) forms.〔 The conditions necessary for a noticeable edge to build up are that: * the cutting speed is low.〔The Open University (UK), 2001. T881 Manufacture Materials Design: Block 2: Cutting, page 14 and 15. Milton Keynes: The Open University.〕 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 Open University (UK), 2001. T881 Manufacture Materials Design: Block 2: Cutting, page 15. Milton Keynes: The Open University.〕 * the metal being cut is one that work-hardens and is reluctant to recover (in the stress-recovery sense).〔 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.〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Built up edge」の詳細全文を読む スポンサード リンク
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