BURR BREAKOUT MODEL DEVELOPMENT AND EXPERIMENTAL-VERIFICATION/

The mechanisms of burr formation and breakout in orthogonal cutting ar e analyzed. A burr formation/breakout model for orthogonal cutting is proposed, based on the observation of SEM micro-machining tests. It is found that a negative deformation plane begins to form when the stead y-state chip formation stops as the tool approaches the end of the cut . Plastic bending and shearing of the negative deformation plane contr ibutes to the burr formation, while crack propagation along the plane causes the breakout. Simulated orthogonal cutting experiments using co pper, Al 2024-T4, and Al 6061-T6 were performed with a modified impact machine to verify the model. The tests showed excellent agreement wit h the model predictions.