Atomized Dielectric-Based Electric Discharge Machining for Sustainable Manufacturing

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

Electro discharge machining process has been successfully employed in aerospace, automobile, and other industries to manufacture high-accuracy micro-parts with range of materials irrespective of their hardness. However, the efficiency of the process has been low due to low energy of individual discharges and accumulation of debris particles in the inter-electrode gaps, especially, when machining micro-scale features. Further, the electro discharge machines use pressure flushing techniques that result in consumption of significantly higher amount of dielectric than needed for an effective discharge process. This award supports research to study an atomized dielectric-based electro discharge machining process that can reduce the consumption of the dielectric 10-20 folds and helping to achieve an environmentally sustainable machining process. The new process will offer unique capabilities of manufacturing high-accuracy components and devices with complex geometries. In addition, the quantitative understanding of plasma discharges in flowing liquid will be useful in a number of plasma applications ranging from water purification to plasma medicine. The overall goal of this research is to improve the efficiency of the micro-electro discharge machining process and produce an environmentally-sustainable machining process by reducing the consumption of hazardous dielectric. The approach is to atomize dielectric and produce a thin moving film that fills inter-electrode gap and flushes out the debris efficiently. This research has four specific objectives: (1) to understand film formation, flow characteristics, melt-pool formation, and debris flushing; (2) to understand the formation, collapse, and discharge of plasma in liquid medium; (3) to establish the relationship between the trajectory of the debris and the dielectric velocity; and (4) to establish relationships between process parameters and machining characteristics (discharge energy, material removal, and debris flushing). To achieve these objectives, a film formation model will be developed using mass and momentum transfer from the dielectric droplets in the spray; a spatially-resolved three-dimensional plasma model will be developed using a fluid-based approach; and the debris flushing model will be developed using the force balance at the flowing debris particle in the inter-electrode gap. To validate these models, experimentally measured data will be compared to model predictions. Film thickness will be measured using high-speed camera, plasma temperature and electron density will be measured using spectroscopy, and debris particle distribution around the discharge location will be determined from the measurements of different sized debris particles using scanning electron microscope.