Printability regimes of pure metals using contactless magnetohydrodynamic drop-on-demand actuation

Abstract

We demonstrate a computational study used to evaluate drop-on-demand printability of liquid metals via a contactless magnetohydrodynamic (MHD) pumping method. We show that the ejection regimes of pure liquid metal droplets can be categorized using two dimensionless quantities: We and a new dimensionless quantity S=Ha2Ca. By plotting We vs S, a linear relationship emerges which relates the velocity through the ejection orifice to the applied magnetic flux density. Additionally, satellite-free droplet generation is shown to be bounded by the ranges 1000≲S≲2000 and 10≲We≲20. These ranges, coupled with the linear We vs S relationship, allow one to predict the critical magnetic flux necessary to eject a satellite-free liquid metal droplet for any liquid metal with a very low viscosity to surface tension ratio (Oh<0.005). We discuss the physics underlying the MHD ejection process and relate the pump action to the dimensionless quantities. We use an MHD finite element model to parametrically sweep through applied magnetic fields and explore two-phase ejection of Al, Cu, Fe, Li, Sn, Ti, Zn, and Zr droplets from a 200 μm orifice. The model is validated using experimental high speed video ejection of Zn and Al, and the reported relationship between We and S can be used to connect the input flux density to the resulting ejection regime.

In-process monitoring and prediction of droplet quality in droplet-on-demand liquid metal jetting additive manufacturing using machine learning

“…The relative motion of the nozzle and substrate creates a three-dimensional part. The momentum pulses required to create and control the rate and size of ejected droplets can be achieved piezoelectrically (Luo et al, 2016a;Wang et al, 2017Wang et al, , 2018, magneto-hydrodynamically (Simonelli et al, 2019;Sukhotskiy et al, 2017Sukhotskiy et al, , 2021, electro-hydrodynamically (Han & Dong, 2017a, b), pneumatically (Beck et al, 2020;Chang et al, 2020;Gerdes et al, 2018), electromagnetically (Luo et al, 2016b), or with a laser (Stein et al, 2018).…”

Multiphysics multi-scale computational framework for linking process–structure–property relationships in metal additive manufacturing: a critical review

“…Other than the processes described above, liquid metal jetting (also termed as droplet on demand 'DOD') is also emerging as a fusion-based alternative where the feedstock need not be metal powders, thereby reducing the manufacturing cost. Liquid metal jetting is based on inkjet printing, where a controlled droplet stream of liquid metal is utilised for near-net shape fabrication [22]. This technique has been primarily appraised for low-melting materials such as tin-based alloys and solder-like metals for electronics applications [22].…”

“…Liquid metal jetting is based on inkjet printing, where a controlled droplet stream of liquid metal is utilised for near-net shape fabrication [22]. This technique has been primarily appraised for low-melting materials such as tin-based alloys and solder-like metals for electronics applications [22]. The applicability of such a technique on high melting point metal systems has not been significantly explored.…”

One-stage simplified lattice Boltzmann method for two- and three-dimensional magnetohydrodynamic flows

“…Indeed, its area of employment is impressively wide. The design of electromagnetic pumps 2,3 and cooling systems for nuclear reactors 4 , the predictions of solar flares 5,6 , the measurement of flow velocities in hot and aggressive liquids 7,8 , and drop-ondemand printability 9 are just few compelling examples of the most challenging applications of MHD.…”