Numerical analysis of grinding temperature measurement by the foil/workpiece thermocouple method

High temperatures generated in grinding are the main factor responsible for thermal damage on the ground surface. The energy partition ratio is often investigated experimentally in order to predict this temperature. The method of the foil/workpiece thermocouple is frequently used. The disruptions of this measurement technique have been studied numerically on a global scale of the wheel by a 2D finite element method taking into account the mica sheets and the constantan foil. The longitudinal thermal inertia of the thermocouple has been determined for various junction thicknesses. The simulations show that the systematic error on the maximum temperature rise (MTR) measurement cannot be neglected and is dependent on grinding conditions such as the workpiece velocity and the arc contact length. Moreover, the junction thickness and the assumed heat flux conducted into the electrode also have an influence on this error. However, the sensor is always accurate during the cooling time outside the foil/wheel contact zone. Consequently, the assessment of the partition ratio is more reliable when made during the cooling phase rather than through the MTR.