A cutting tool includes a shaft, and a sensor device disposed in such a manner as to surround a portion of the shaft. The sensor device includes a sensor module including first sensors, a substrate connected to the first sensors, and a wireless communication unit connected to the substrate and configured to transmit a signal including information detected by the first sensors to outside and a housing accommodating the sensor module. A region of the shaft surrounded by the sensor device includes a first region having a shape of a 4n-sided polygon when viewed from a direction in which the rotation axis extends. The plurality of first sensors are arranged on at least two of outer peripheral surfaces of the first region, perpendicular lines of the outer peripheral surfaces passing through the rotation axis and intersecting at 90 degrees.

The present disclosure relates to system for shearing material. The system can include a machine including a tool that rotates around an axis at a speed of rotation (f.sub.ROT) for shearing a raw material workpiece; wherein said tool[has at least one tool edge can engage the raw material workpiece; a vibration sensor can generate an analogue measurement signal (S.sub.EA) dependent on mechanical vibrations (V.sub.IMP) emanating from rotation of said tool; a position sensor can generate a position signal indicative of a rotational position of said rotating tool; and status parameter extractor.