In-Process Monitoring of Surface Roughness Utilizing Ultrasound

This paper presents the capability of an ultrasonic system for the in-process surface roughness measurement of machined parts. The system uses a focused ultrasonic transducer to measure the reflected amplitude variation of an ultrasonic beam incident on the surface. The robustness of the system is examined by applying the technique to different machined surfaces and investigating the effect of various coupling fluids. Experimental results show that the technique is applicable to the surfaces produced by most production processes. In addition, the capability of in-process measurements is demonstrated by adapting the system to a CNC machining center. Results show in-process measurements correlate well with off-line profilometer data. Tolerance to machine vibration is also shown by comparing the measurement data with the machine spindle on and off.