Improvement of a Fast Tool Control unit for cutting force measurement in diamond turning of micro-lens array

This paper describes a Fast Tool Control (FTC) unit integrated with a piezoelectric force sensor, which is designed for in-process measurement of the cutting force during the fabrication of micro-lens array. The piezoelectric force sensor integrated with the FTC unit is designed to have a stroke of 48 gm, a bandwidth of 7837 Hz and a stiffness of 34.67 N/mu m. The micro-lens array is fabricated with a length of 190 pm and a depth of 5.2 pm on the oxygen-free copper surface and the Ni-P plating surface. The measured cutting forces of the oxygen-free copper surface and the Ni-P plating surface were 0.54 N and 0.92 N, respectively. The cutting tool wear could be detected through monitoring the cutting force by developed FTC unit integrated with a piezoelectric force sensor.