Energy and Deformation in Modulation Assisted Machining
Modulation Assisted Machining (MAM) involves material removal by controlled superimposed application of low frequency modulation (<1 >kHz) to machining. Prior work has shown that, by controlling chip formation to occur discretely and enhancing fluid action at machining interfaces, MAM enables up to 3-fold increases in the material removal rate. In the present study, the effects of modulation on specific energy of machining and deformation field of chip formation are examined. The specific energy is estimated from cutting forces that are measured utilizing a newly developed force measurement system of high natural frequency. Reductions of 40-70 percent in the energy are observed relative to that in conventional machining, when cutting metals such as copper and aluminum alloys. Evidence based on high speed (in situ) imaging of the metal flow in chip formation, chip structure and strain, stored energy of cold work, and recrystallization of chip material is presented to show that this reduction is due to chip formation in MAM occurring at smaller strain levels. Unique observations pertaining to highly sinuous flow of metals at room temperature have emerged from the imaging experiments. A simple geometric (aspect) ratio of the length to thickness of the 'undeformed chip' is shown to be a predictor of the transient chip formation conditions that result in reduction in specific energy and deformation levels.
COMPTON, Purdue University.
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