On-Line Monitoring of Drill Wear Using Air-Coupled Audio Microphone when Drilling Composite Materials

Abstract

The condition of the cutting tool when drilling composite materials is the controlling factor for the surface integrity of hole produced. The high rate of tool wear when drilling composite materials makes finding a way to monitor the condition of the cutting tool without interrupting the drilling process a great necessity. Inspecting the condition of the drill between or during the drilling process is not practical or economical. In an attempt to tackle this problem, a new approach of on-line tool wear monitoring method using an air-coupled audio microphone is proposed. An experimental investigation was conducted on multi-directional carbon fiber reinforced plastic (CFRP) composite material using a high speed steel (HSS) drill. The result shows that, the amplitude of the acoustic signal from the microphone decreases when the amount of flank wear increases and the amplitude of thrust force and torque increases with the increase of the flank wear. This result demonstrates that the proposed approach can be used as an effective and economical tool for on-line monitoring of cutting tool condition.