Inkjet Printing at Megahertz Frequency
Inkjet printing enables more efficient, economic, scalable manufacturing for a wider variety of materials, than other traditional additive techniques. However, the jetting frequency of commercial droplet-on-demand inkjet techniques is mostly limited to ~10 kHz. This paper presents an investigation of the possibility of jetting at megahertz frequencies in order to boost the productivity of inkjet by ~100 times. The key to this problem is rooted in droplet formation dynamics, a subject that has been extensively studied for over 300 years. Hence, the focus of this paper is to understand the limitations of generating droplets at a megahertz frequency and explore possible solutions for overcoming these limitations. The paper begins with a review of literature on the dynamics of droplet formation. A numerical model is then developed for the simulation of droplet formation dynamics. The numerical model is validated against available experimental data from the literature. Aided by insights gained from scaling analysis, the validated model is then used to study the effects of different process parameters on high frequency jetting. The study finds energy density input to the nozzle is the key to achieve megahertz frequency printing.