Jetting Mechanism, Simulation And Experimentation Of Micro Scale 3D Printing Based On EHD

Additive Manufamring( AM) is emerging as an advanced manufacturing technology based on the principles of laminated fabrication, its most typical technique is the 3D printing. 3D printing can be quickly and accurately create arbitrarily complex three-dimensional structures by using three-dimensional design data, to solve the problem that it is difficult for traditional methods to manufacture complex three-dimensional structure parts. Complex three-dimensional micro- nano structure has important application in modern industry, and micro scale 3D printing based on EHD(Electrohydrodynamic jet(E-jet) printing) is an emerging and promising micro/nano scale 3D printing processes. It has demonstrated outstanding strengthens and high potentials in term of high resolution, low cost, easy operation, the ability to utilize multiple materials in the same overall print- head, large area patterning. E-jet printing has the capability to create complex 3D micro/nano-structures with low cost and high resolution. On this paper, the spray mechanism and working principle of E-jet printing were preliminary explored,and the affection of different process parameters on the E-jet printing results were studied, and eventually determined the working conditions that ideal printing should have.Based on the combination of classical hydrodynamics and electrodynamics theory analysis, this paper has expounded the printing principles systematically,and the force of conductor liquid and dielectric liquid in the Electrostatic field has analyzed separately. The force of Taylor cone in the cone jet mode has analyzed, and the form change of the liquid in the capillary tip at different voltages and air pressure also has analyzed theoretically. And analyzed the hardware foundation of EHD micro printing experimental platform, and determined the basic hardware configuration, and experimental equipment and material performance requirements were discussed necessarily.Combined the theoretical analysis of E-jet printing, simulates the droplet Deformation and cone jet process in electrostatic field. Calculated the change process of the cone shape at different voltages and pressures, and ultimately get the same result with the theoretical analysis.Set up experimental device of the E-jet printing, and observed the printing process by experiment, we studied the changes of jet mode under different voltage and pressure during printing process, and the correctness of theoretical analysis and numerical simulation has verifed. The print mode is related to voltage and inlet pressure. The voltage is larger and cone shape is shorter, and the multi- jet will be apperd when the voltage was too high. The inlet pressure is greater and the cone jet will be longer. Too great pressure will make the cone jets tend to vertical jet, and the cone jet will disappears. It says that cone jet mode could form in a certain voltage and pressure range, E-jet printing also could be finish properly, rather than a specific voltage and pressure values.With combined the numerical simulation results and experimental laws of printing under DC voltage, further studied the printing effect law under pulse voltage. Wherein, the frequency was bigger and the diameter of the deposit droplet will be smaller. If the frequency was constant, the deposited droplet diameter will increase with voltage amplitude or inlet pressure increase. Meanwhile, if loss of the one-to-one relationship of droplet ejection frequency and pulse frequency, we can still get their correspondence by increased the voltage amplitude or air pressure, which is of great significance to improve the frequency and efficiency of E-jet printing. Ultimately through 160 μm diameters of printing needles, we obtained the droplets which the ejection frequency is 300 Hz and the average diameter is 52.3μm, established an ideal spray printing process conditions.