Dynamic Shear Stress Evaluation on Micro-Turning Tool Using Photoelasticity

The paper presents an experimental methodology for evaluation of shear stress induced on a micro-turning tool during micro-turning operation. A micro-turning tool manufactured by Sandvik Coromant was used for micro- turning of a brass spindle. The front face of the tool was cleaned, polished and coated with a thin layer of Ethylene-Vinyl Acetate (EVA), a birefringent material. Subsequently, reflection photoelastic experiments were conducted to find the shear stresses induced on the micro-tool. A custom designed grey field poledioscope was used for this purpose which was pre-calibrated and verified using disk under compression test. The tool was subjected to turning operation and dynamic images of the tool were captured using Casio ELIXIM ZR-200 camera in high speed movie mode at 1000 fps (frames per second) for four different orientations of the analyzer simultaneously. These images were processed using a code developed in MATLAB software to generate a shear stress map of the tool dynamically at different time instants of the machining process.