This paper will introduce a new sensor coupling device for milling machines, drilling machines and for the machine center. Within the industry there has always been the need for a practical application of the sensor coupling device to detect the cutting process related signals from the “tool side”. A mounting device which enables the sensor to be fixed close to the rotating multipoint cutting tool has been developed to meet this need. Thus a more practical method for detecting the tool fracture of twist drills and/or tool chipping of an end mill cutter becomes possible. The machining process associated signals are high frequency Acoustic Emission (AE) signals detected from the spindle top of the machine being used. In this study two kinds of AE-signals will be compared. The first are those detected from the spindle housing. The second are signals detected from the spindle top using the newly developed sensor coupling device. Furthermore, the structure of an AE-monitoring system for supervising multipoint cutting tools will be described. In addition, results of experiments which monitor the tool health coefficient, derived from the power spectrum of the machining signals, will be discussed.
