The results of research are presented whose objective was to develop a remote thermocouple technique for measuring cutting temperatures in a turning operation. The measuring scheme relies on the signals from two standard thermocouples located beneath the cutting tool insert. These signals are fed into an analog computer which calculates on-line the temperature at the tool point. The on-line computation provides an estimate of the tool point temperature within about one second rather than requiring the tool thermal system to come to steady state before temperatures are estimated. The research included two development phases. The first involved the use of digital computer simulations of the heat transfer process in a generalized cutting tool. This led to the derivation of a simple equation to estimate the cutting temperature from measurements taken at two remote points. The second phase concerned experimental validation of the computer simulations under a variety of cutting conditions.

This paper shows the development of a mathematical model for determining the average interface temperatures when using a remote sensor. The accuracy of the remote sensor technique was greatly improved by introducing an insulator between the tool and tool-holder. The presence of the insulator provided boundary conditions which enabled a numerical solution to the set of equations representing heat flow and temperature distribution. The model was compared experimentally with a tool-chip thermocouple, and agreement of the order of ± 6 percent was observed. The model can be used not only to determine the average tool-chip interface temperature, but the temperature distribution of the overall tool. The developed model proved to be somewhat insensitive to physical constants and the surrounding environment. Its use as a practical, accurate method for determining cutting temperatures is possible without the need for calibrating tool-chip thermocouples, complicated experimental setups, tedious iterative calculations, over-generalized assumptions, and unavailable physical constants for tools and work materials.

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Transmission electron micrographs are presented which show evidence of plastic deformation in the form of high densities of dislocations and twins in the subsurface of the crater area of polycrystalline alumina cutting tools. The inverse dependence of crater area on hardness for four different tool materials suggests that plastic flow controls the rate of crater wear.

While not statistically significant, these results suggest that the intervention for employees at high risk of STD achieves practical and clinical significance by achieving absolute and relative reductions in risk of STD of 3% and 15%, respectively.