Predictive modeling of microhole profile drilled using a focused electron beam with backing materials

Abstract

This study establishes a simple and rapid predictive model for a microhole profile drilled using a focused electron beam based on the finite difference method. Vertical irradiation and full penetration using a focused beam with a Gaussian distribution were reflected onto the three-dimensional mesh of metallic substrates. The predictive hole profiles on the substrate were estimated by analyzing the phase transition using predictive temperature distributions. To validate the predictive accuracy of model, experimental drilling processes on AISI 304 stainless steel substrates were conducted, and the experimental hole qualities were measured using microcomputed tomography. Comparisons between predictive and experimental results represented high predictive accuracy in three criteria: hole diameters, straightness, and geometrical hole shape. Applying the fractional energy absorptance dependent on the substrate depth significantly improved the prediction accuracy of model. The predictive results demonstrated that the thermal analysis with temperature distributions could predict the drilled hole qualities rapidly and accurately, avoiding the high computational loads from considerations for velocity fields or pressure distributions around the substrate.