Direct Observations of the Chip-Tool Interface in the Low Speed Cutting of Pure Metals

Abstract

An experimental study of the chip-tool interface and its evolution in the low speed cutting of metals has been carried out. Specially prepared transparent glass and sapphire tools have been used to cut commercially pure metals such as lead, aluminum and copper. The chip-tool interface has been observed in situ using optical microscopy and recorded on film and video tape. By observing the motion of inhomogeneities in the chip, and profilometry of the chip and tool surfaces, it has been established that there is intimate sliding contact between the chip and the tool at and near the cutting edge. Farther away from the cutting edge and close to the end of the chip-tool contact, metal transfer and sticking are observed between the chip and tool surfaces. It has been shown that metal deposition on the rake face initially occurs near the point at which the chip curls out of contact with the tool and progressively extends outward and away from the cutting edge in conjunction with an increase in the length of contact as cutting progresses. The sticking and sliding zones are unchanged when these pure metals are machined with tungsten carbide tools.