Shear Deformation in Chip Particulates Produced Using Modulation Assisted Machining

Controlled breakage of chip-tool contact during modulation assisted machining (MAM) produces the chips as particulates at a rate of frequency of modulation. Particulates of different shapes and size ranging from 100 mu m to 5mm and aspect ratio of similar to 10 were produced using different modulation and machining conditions in MAM. Scanning electron microscopy and tool maker's microscope was used to evaluate morphology and size of the particulates produced at different conditions. Shear strain imposed in particulates was estimated from the undeformed chip length and actual chip length. Microstructure characterization of bulk brass and chip particulates was done by optical microscopy and electron back scatter diffraction. Results show that there existed ultrafine grained microstructure at the edge of chip particulates, while the central area of the chip particulates has elongated and equiaxed grained microstructure. Average shear strain for chip length ratio 0.511 was found to be 2.32 for the particulates.