Ultrasonic Thermometry for Manufacturing Materials Using the Pulse-Echo Method

Core temperature of workpieces during manufacturing processes can vary significantly from the surface temperature. If the thermally induced expansion of the workpiece is estimated using the surface temperature, it may lead to a wrong estimation resulting in over or under-compensation for the effects of thermal expansion. Ultrasonic thermometry has been shown to measure the core temperature of steel sample of 100 mm (EN24T) with a resolution and accuracy of better than 0.5 °C and ±1 °C[1]. This study establishes the suitability of ultrasonic thermometry for other metals namely brass, stainless steel, aluminium, and mild steel. By using a calibrated temperature bath, the ultrasonic time-of-flight for different metals was measured. This was done to establish the relationship between the materials and the ultrasonic time-of-flight (TOF) in them at different temperature. The model that will be created using this measurement method can be used during dimensional inspection or subtractive manufacturing processes to aid the control or compensation for the effects of temperature change.