“…Specifically, when employing these technologies, the cutting tools are extracted from the manufacturing machine and placed on the measuring instruments to inspect the cutting tool conditions directly. Indirect monitoring technologies measure sensing signals corresponding to the insert condition during the machining process, including information, such as cutting force [ 5 , 6 , 7 , 8 , 9 ], vibration [ 10 , 11 , 12 ], acoustic emissions [ 13 , 14 , 15 ], temperature [ 16 ], and sound [ 17 ], and subsequently analyze the signals for tool condition classification. Indirect monitoring technologies have lower tool condition classification accuracy than do direct types; however, they are applicable for online tool condition inspection.…”