Tool Temperature Analysis in Face Milling Using an ESP32-C3-Based Measurement Approach

Reliable temperature measurement on rotating milling tools remains challenging, particularly under flood cooling, where optical access and sensor integration are restricted. This study develops a compact, tool-integrated measurement system combining an embedded Type-K thermocouple, analog signal conditioning, ESP32-C3-based data acquisition, local microSD storage, and Wi-Fi data transfer. A sealed housing enables operation under cutting-fluid exposure, while local storage decouples acquisition from wireless communication. The system was evaluated through face-milling experiments on 42CrMo4 steel at three cutting speeds and three feed-per-tooth levels under dry cutting and flood cooling. Within the investigated conditions, feed per tooth exerted the strongest influence on the measured internal tool temperature during dry cutting. Temperatures reached approximately 175–235 °C under dry cutting and remained generally below 70 °C under flood cooling, which also reduced their sensitivity to cutting parameters. The measurements additionally supported inverse calibration of a three-dimensional finite element model to investigate heat transfer and heat partitioning. From an industrial perspective, the system provides an accessible approach to acquiring internal tool-temperature data during dry and flood-cooled milling without specialized rotary telemetry hardware. These measurements can support cooling-strategy assessment and thermally informed process-parameter selection, while providing a foundation for future tool-condition monitoring and adaptive machining.