Comprehensive examination of a new mechanism to produce small droplets in drop-on-demand inkjet technology

For drop-on-demand inkjet technology, the capacity to reduce the inkjet droplet size without changing the size of the nozzle orifice would beneficially impact coating, processing, and maintenance attributes. To examine droplet sizes emanating from prescribed nozzle orifices, this manuscript applies numerical simulation based on computational fluid dynamics and an in-depth assessment of relevant parameters associated with producing liquid droplets, and then compares the outcomes with published data. For a given liquid, six distinct flow regimes were determined to affect droplet sizes, the critical characterization of which could be effectively assessed by using two non-dimensional parameters, including the Weber number, We, and a newly defined, non-dimensional temporal frequency number, Ω. The use of the regimes enables the specification of operational conditions to control and minimize droplet sizes to less than 20 % of the nozzle orifice diameter and up to 150 times smaller droplet volumes from nozzle orifices. As a consequence, a new method is proposed that would be useful for lowering droplet sizes while maintaining desired droplet quality for deposition on and coating of surfaces.