Simulation Study Of Pneumatic Driven Micro Droplet Jetting Deposition Process

Freeform fabrication with micro-droplet Jetting is a new technology developed on inkjet printing technology,Its core is the use of outside pressure to force the material to form droplets from the nozzle deposited on the substrate.The technology has high forming accuracy,widely available materials and non-contact characteristics,which has broad application prospects in the fields of manufacturing of flexible conductive lines.Droplets deformation directly affect the molding accuracy and quality,so the precise control of droplet deposition form is widely used in the premise and condition,so it is necessary to clear the regular of various factors in the droplet deposition process.So as to achieve precise control of droplet deposition morphology.Based on this,this article adopted the theoretical analysis and simulation research method to studied the deposition process of the droplets collide with a substrate,established the simulation model droplets collide with a substrate,analyzed the impact of the flow field for the deposition patterns,researched the influence of different parameters in the deposition process,on this basis,the two adjacent droplets collide with a substrate deposition process analysis to provided theoretical guidance for experiments.First,the establishment of the droplets collision with a substrate deposition simulation model.Analyzing the deformation process of the droplets collide with a substrate,using the GAMBIT software to establish simulation model combined with the experimental conditions,using the VOF method to track the droplet surface,utilizing the FLUENT software to simulate droplets collide with a substrate deposition dynamic process.Secondly,the regular study of the different parameters on the deposition morph ology.Based on the model established,this article analyzed flow field and pressure field on the spreading patterns and researched the regular of the velocity,surface tension and contact angle on deposition process.Simulation results showed that:(1)the greater the initial velocity of the droplet,the faster sprawl,the bigger the sprawl range,but the final form of the droplet size has nothing to do with the speed;(2)the smaller the surface tension of the droplet,the bigger the sprawl range,the slower the retraction process,the less obvious the reaction;(3)the contact angle represent wetting degree,the greater the contact angle,the worse the hydrophilic,the smaller the maximum diameter of droplet sprawl and the shorter the time,the shorter the corresponding retraction oscillation time,the longer the time to stable.Based on previous studies,the establishment of two adjacent droplets collide with the substrate deposition simulation model to analyze the droplets morphological feature and the regular of the droplet coincidence rate and the contact angle from the initial relative position of the two adjacent droplets and substrate properties to droplet deposition,at thesame time,the article analyzed the central location of steady-state time to provide theoretical guidance for subsequent experiments.Finally,the article used the self-developed pneumatic micro-droplet jet device,adopted high-speed image acquisition system to collect droplets collide with a substrate deformation process in demand and controlled injection conditions,and to compared the simulation results with experimental photo.Simulation results and experimental photographs were compared and it indicated that the model established in this paper is reasonable and feasible.