Feasibility study of rapid prototyping using the uniform droplet spray process

Abstract

This work studied the feasibility of rapid prototyping using the Uniform Droplet Spray (UDS) process. Straight and stable liquid metal jets are crucial requirements in the application of UDS to rapid prototyping. Methods to maintain the jet straight and stable were developed. Hardware improvements include an auxiliary orifice mounting fixture and a new crucible bottom with a tightly-fitting orifice-pocket. A droplet trajectory controller, including deflection plates and a pulse provider to a charging plate, was developed to precisely deliver droplets for deposition. The degree of separation between deflected and undetected streams of droplets was modeled and the prediction was compared with experimental results. This comparison revealed that the degree of actual deflection was approximately twice as high as the predicted value. Using the trajectory controller, deposition was conducted using pure tin (Sn) with droplet impact conditions of velocity and liquid fraction of 45 m/s and 97%, respectively. The deposition frequency was varied in the experiment to study its effects on deposit shapes. A low frequency deposition at 57Hz produced a vertical pillar, whereas a high frequency deposition at 574Hz resulted in a large drop.