Slow Speed Machining of Titanium
MATERIALS RESEARCH LABS ASCOT VALE (AUSTRALIA)
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Catastrophic-shear type chips are produced in machining titanium. These are shown to be formed by a cyclic process of indentation and catastrophic shear. The deformation within the chip was very heterogeneous most of the deformation occurring in narrow shear bands between the segments. A model of chip formation has been proposed based on orthogonal planning and machining in the scanning electron microscope. Cracking was often associated with the shear bands and this degraded surface finish. The change to a continuous chip at low cutting speeds reported by Recht was not observed and furthermore, the surface finish further deteriorated. Decreasing the depth of cut, rake angle, or using tools having a large nose radius made the chip less segmented and consequently improved surface finish. The depth of deformation beneath the machined surfaces increased with increasing depth of act and decreasing rake angle. Machining with a lubricant decreased the depth of deformation.
- Properties of Metals and Alloys
- Fabrication Metallurgy