| In metal machining, chips must be effectively removed from the cutting zone to prevent them from damaging the part, the tool, or the machine. Cutting fluids have been utilized in the past to flush chips away from the cutting zone. With the increased emphasis that society places on the environment, however, it is desirable to eliminate cutting fluids from machining operations. To eliminate fluids as a chip transport medium, we must be able to accurately predict the morphology and kinematics of chips for given process conditions (e.g., feed, speed, tool material and nose radius). Once the chip behavior can be accurately predicted, it can be effectively controlled by manipulating process variables, thereby facilitating dry machining.; Once initial chip curl and constrained chip spiral characteristics can be predicted, they can be optimized as part of the overall cutting process design. In this research, the effects of cutting conditions on chips in drilling is presented to determine the statistically significant cutting conditions with respect to dominant chip mass. The effects of chip mass on drilled hole surface finish is shown. A new methodology is presented to develop a Johnson-Cook constitutive model for workpiece materials for the purpose of predicting cutting forces at the tool and the stresses on the shear plane. Analytic and experimental work is performed to investigate initial chip curl and to model it as a function of workpiece properties. Numerically generated chips are created to investigate the effects of obstruction geometry on chip growth after the chip has impacted an obstruction. Experimental work is done to investigate the effects of cutting conditions on constrained chip spiral morphology and to develop a predictive chip semi-spiral morphology model. The process inputs which have statistically significant effects on the morphology of the chip once it has impacted an obstruction are determined to confirm the model. |
