Deviation between the sliding direction of the chip over the tool and the direction of the friction force in oblique cutting

Abstract

Pure oblique cutting experiments with conventional cutting tools as well as ultra-sharp tools have been carried out under a wide range of cutting conditions using a linear slide based cutting set-up. The chip flow direction was measured using the 3D Digital Image Correlation (DIC) technique of high-speed stereoscopic images and the frictional force direction was determined from forces. It is estimated that the error in chip flow angle measurements using DIC, was approximately ±1°, as was the error in friction force direction measurements from forces. An increasing trend of the angles with an increase in feed and a decreasing trend of the angles with an increase in speeds were observed. It was found that under many conditions, there is a significant difference between the chip flow direction and the friction force direction. This difference decreases with increase in friction co-efficient and with increasing sharpness of the cutting edge. However, with ultra-sharp microtome knives there is a small but finite difference between the chip flow direction and the friction force direction. By the use of DIC to measure the chip flow angle at different points along the back of the chip, it is found that there was no variation in chip-flow angle over the width of the chip.