Fiber Bragg Grating Sensor for Temperature Measurement in Micro Turning of Optical Surfaces with High Surface Integrity

Abstract

This article presents the use of Fiber Bragg Grating (FBG) sensor to measure the temperature induced at the tip of the tool, while micro-face turning of optical surfaces. FBG sensor of 120 μm diameter was mounted near the tip of the tool and the shift in Bragg wavelength due to induced temperature was acquired with the help of an interrogator. The experiments were conducted on a Taylor Hobson DT-250 SPDT machine, over three different optical grade alloys namely Aluminum 6061, OFHC (Oxygen free highly conducting) copper and stainless steel. It was observed that while machining stainless steel, temperature at tool tip was highest and in case of OFHC copper it was lowest. The roughness and waviness of machined optical surfaces were measured using PGI 400 Profilometer. The results confirm that temperature induced in micro cutting and the rate of heat dissipation of work material contributes significantly to optical surface integrity.