A Multiphysics Approach Based on Using Thermal, Mechanical, and Acoustic Measurements in Milling of SKD11 Carbon Steel

Milling of hardened carbon steels like SKD11 generates complex physical interactions that can affect tool wear, surface quality, and process stability. This study presents a multiphysics experimental approach aimed at better understanding these physical interactions. The first objective is to monitor key features in real-time, including cutting force, vibration, cutting temperature, and sound signal, during the milling process. An integrated setup involving infrared thermography and thermocouples, a piezoelectric dynamometer, sound and vibration emission sensors was used, and data were collected under two different cutting conditions. The second measurement objective is to inspect the end-of-process features such as surface quality, tool wear, and chip formation. Tool wear was measured by different methods at the end of the cut in order to show the strong correlation between cutting forces, temperature, sound signal, and vibration patterns of the machining process. The results of this study are focused mainly on the design approach rather than on detailed numerical details. The tooth-passing frequency analyzed from the cutting-force signal was correlated with the sound signal. Cutting strategies affect the surface quality under the same cutting conditions. This work provides guidance on eliminating redundant measurements for multiphysics investigations of the milling process, and accounts for all features, in contrast to previous experimental studies. Besides those findings, there are some issues that need to be improved, such as repositioning the thermocouples, elongating the cutting path to inspect the tool state and surface quality; more cutting conditions should also be applied.