ASSESSMENT OF CHIP BREAKING CHARACTERISTICS

Abstract

The formation of continuous chips in metal cutting operations often leads to chip disposal problems. Chip-breakers play a predominant role in the effective control of chip-flow and chip-breaking, especially at high cutting speeds, for the easy and safe disposal of chips, as well as for protecting the surface-integrity of the work piece. The dissertation deals with basic information regarding chip breaking like practical problems, need for breaking chips, and chip control in machining with grooved tool inserts. It deals with various factors affecting chip breaking and their influence while breaking chips. It contains various conventional methods of chip breaking and gives brief details about chip breaking by various type of grooved inserts. Experimental studies have been conducted to deal with the chip-breaking characteristics during turning operations. To assess the chip-breaking characteristics parameters like chip breaking cycle time, specific cutting energy and a new parameter called the chip-breaking index, CB, is employed. Out of these three parameters, CB is found to be more effective to assess the characteristics. This index is defined based on the thickness and length of the broken chip. The shape of broken chip, chip-breaking cycle time and specific cutting energy are appraised to determine the optimum cutting conditions for effective chip-breaking. Properly controlled chips were produced with the CB values under 0.06. When the CB values exceeded 0.06, the chips were found to be uncontrolled, regardless of the types of chip former used.