As machining technology develops toward the unmanned and automated system, the prediction of chip breaking is considered increasingly important, especially in continuous machining such as in cutting aluminum alloys. In this paper, chip breakers with different parameters are designed to produce chips that can be evacuated easily and reliably from the working zone. The formulation of chip up-curl radius is constructed through analyzing the chips subject to chip breaker. The predictive model of chip breaking is developed based on chip breaking conditions. Chip breaking strain is obtained by using backward-deducing method and cutting experiments. In order to verify the model, PCD tools with chip breakers are used to cut LY12, chip breaking areas are compared with those obtained from the predictive model. Results show the chip breaking predictive model is reasonable.