Design and Operation of a Droplet Deposition System for Freeform Fabrication of Metal Parts

Abstract

Based on a linear stability theory for liquid jets, the design of a droplet generator system is presented for freeform fabrication. The linear stability theory of forming droplets is first reviewed and its suitability to the present droplet deposition system is then discussed. The analytical formulae for predicting droplet size and break-up length at optimal conditions are developed. Based on the present formulation, a droplet generator is designed and built to make wax and tin alloy droplets. Experiments have been conducted at a wide range of jet velocities, frequencies, and droplet sizes. Good agreements are found between the analytical predictions based on the linear theory and experimental results. It has also been found that using the present design and procedure recommended, the droplet sizes can be controlled having a size deviation of less than 3 % and the variation of the deposited layer can be managed within 3% of its width deposited.