THE EFFECT OF REVERSE SHEAR ON THE FAILURE OF METAL-CUTTING TOOLS

Finite element models of a metal cutting tool have been developed to examine the reverse shear mechanism. The stress distributions at both tool/work engagement and disengagement have been studied. Direct and shear loads have been applied both separately and simultaneously. A reverse shear as well as a diminishing direct loading during disengagement have also been modelled. It was found that under certain cutting conditions reverse shear could have very strong influence on the stress distribution within a cutting tool. However, it was also found that mechanical stresses alone would not have caused unexpected tool failure for a properly designed metal cutting tool. Thermal stresses generated upon tool/work engagement and disengagement also play a very significant part in influencing the performance of metal cutting tools. The combined effect of a built-up-edge and reverse shear on tool performance has also been discussed.