A Geometry-Based Chip Thickness Model for Microdrilling of Hardened Steel

Abstract A geometry-based chip thickness model is proposed to enhance the understanding of chip behavior in the microdrilling of Stavax hardened steel under dry condition. Chip formation at specific cutting regions, including the primary cutting blade, secondary cutting blade, and chisel indentation zone, is evaluated in the model. The cutting size effect is incorporated into the model to address the unique plowing and shearing phenomena. The model is experimentally validated over a range of chiploads. The progression of chip morphology is observed. Overall chip thickness is shown to be thicker as compared to the theoretical chip thickness. Both experimental and analytical models show a strong dependence of chip thickness, chip thickening rate, and morphology on the size effect that dictates the effectiveness of the chip removal process.