Evaluation of Chip-Tool Interface Conditions using Transparent Tools

In-situ high speed photographic observations through transparent ceramic cutting tools have been used to observe the dynamic contact interactions at the chip-tool interface while cutting commercially pure copper under a range of cutting speeds and rake angles. Under all conditions it is observed that the chip slides over the rake surface of the tool close to the cutting edge. Under low cutting speeds some chip material is transferred to the tool where the chip curls out of contact with the tool in the form of a fairly thick deposit. At higher cutting speeds a fine layer of chip material is transferred to the tool closer to the cutting edge and the thick deposits formed at lower speed are removed. The tendency for deposition is decreased as the rake angle is decreased. In all cases the dynamic nature of the cutting process and the slow evolution of the deposition are clearly evident.