GOALI/Collaborative Research: Mechanics and Dynamics of Low Frequency Vibration Assisted Machining

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This Grant Opportunities for Academic Liaison with Industry (GOALI) project partners two universities with industry in the fundamental research on the effect of applying slow vibrations to enhance material removal in machining processes. Vibrations have been treated as a disturbance and a source of inefficiency to many manufacturing operations including machining processes. However, this new approach attempts to use low frequency (slow) vibrations to improve the contact conditions between the cutting tool and workpiece and thereby improve machining efficiency. By applying controlled slow oscillations to cutting tools, this new cutting process can enable material removal with lower cutting effort and energy, attain longer tool-life, and improve overall stability of the machining process towards higher material removal rates. It can significantly enhance manufacturing productivity, and hence US competitiveness and prosperity, and product quality especially for components made of difficult-to-cut metal alloys employed in U.S. automotive, aerospace, defense and energy sectors. Collaboration with a partner from US automotive industry will help ensure the technology transfer and enhance student training.This project investigates the mechanisms by which low frequency vibration applied in continuous cutting process can alter and improve the cutting mechanics and dynamics. Modulating the tool at low frequency along tool feed direction transforms continuous cutting into discrete cutting. This new discrete cutting kinematics not only alters the deformation mechanics of chip formation, but also changes the thermomechanical dynamics in the cutting zone as well as the dynamic stability of the machining process. This research will analyze chip formation mechanics through in-situ digital image correlation and develop analytical models to understand the relationship between vibration kinematics, including cutting force and energy, and overall material removal effort. As the low frequency modulation periodically disengages the cutting tool from the workpiece, it interrupts continuous heating of the cutting edge and induces pre-determined cool-down periods to reduce tool temperature. Analytical models and experimental characterization will capture this transient and cyclic heat conduction regime and its thermo-mechanics. It will provide optimal cutting strategies to increase the tool-life. Finally, effect of feed modulation on the coupled dynamics of process and the machining equipment will be investigated. New knowledge will be created on how to use the controlled low frequency vibration to control and suppress high-frequency self-excited chatter instabilities during machining. It will allow machining of precision parts at significantly higher depth, feed and speed leading to greater material removal rates.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.