The aim of the presented work was to define a criterion for the prediction of chip breakage in turning C45E+N (AISI 1045). The chip formation, the chip flow and the expansion of the chip due to collision with the periphery were modelled three-dimensionally using the Finite Element Method (FEM). The mechanical loads in the chip breakage zone were determined by comparing the modelled chip with high speed filming records of the real chip breakage cycle. Based on the calculated loads in the chip breakage zone a novel damage criterion based on an approach of Johnson and Cook was developed. This criterion enables the FEM-model to simulate chip breakage three-dimensionally for different tool geometries and varying cutting parameters. The enhanced FE model correlated well with high speed filming records of the chip flow and breakage as well as with the empirical determined cutting forces and chip temperatures.