
52 Fundamentals of Machining Processes
of a poor surface nish. The BUE changes the geometry of the cutting tool.
BUE is generally undesirable in many cases; however, a thin, stable BUE can
protect the cutting tool from excessive wear. The presence of a large and
stable BUE causes failure of the cutting tool. This occurs through severe cra-
ter wear caused by metal fragments at the back of the chip and by abrasion
of the tool ank due to the presence of hard fragments of BUE adhered to
the workpiece surface.
Experimental evidence indicates that the BUE occurs under the following
machining conditions:
• Ductile materials such as mild steel, copper ...