On-line monitoring approach of cutting tool fracture in automatic machining

A technique of detecting cutting fracture by simultaneous monitoring both the spindle motor current and acoustic emission (AE) during the cutting process is reported. A holler current sensor and a new type of AE sensor which transmits the AE signal through the lubricant are used to catch the required signals. The comprehensive estimation principle of cutting tool fracture, monitoring plan, and experimental results are introduced. The drills breakage with diameter over 0.6 mm and turning and milling cutters' crack with area over 0.2 mm² can be detected automatically by the system. The rate of success in detection approaches 98% or higher.