Tool Fracture Probability of Cutting Tools Under Different Exiting Conditions

Abstract

A large number (150) tungsten carbide (6 weight percent) cutting edges were used to make single cuts in AISI 4340 steel (HB = 235 kg/mm2) at a cutting speed of 200 fpm (61 m/min) and a variety of feeds and entrance and exit angles of workpiece taper. A map is presented showing types of brittle tool fracture occurring at exit for a wide range of feeds and exit angles. Fractures were of two types: 1) those due to very sudden unloading of the tool at exit, and 2) those due to metal adhering strongly to the tool face following a cut. Reasons for the two types of exit failure are briefly discussed.