Various drop-on-demand (DOD) inkjet systems that can precisely deliver droplets have been developed in recent years to produce cementitious materials; however, production of reliable components has not yet reached its full potential. This is due to a lack of understanding of the governing factors that affect shape accuracy, and mechanical performance. This research focus is the fluid intrusion behavior in powder beds since this is an important step that determines the final properties of printed parts with selective cement activation method.
Droplet size and velocity in a DOD system is determined by the designed driving waveform, fluid pressure and fluids physical properties. Because the influence of droplets’ features on the powder-binder interaction is not independent of other printing parameters (including printing speed and layer thickness), a statistical approach is developed to study the effect of droplet size and velocity in tandem with significant printing parameters to evaluate their effect on fluids intrusion into the powder bed.
The two materials used in this study are ordinary Portland and calcium aluminate cements; aqueous solutions were developed for each type of cement as dispensing liquid and their rheology were studied to investigate the jet-ability of fluids. A waveform editor and a drop-watch camera system allows manipulation of the electronic pulses to the piezo jetting device for optimization of the drop characteristics as it is ejected from the nozzle. Waveform is an independent factor that, together with "printing speed" and "layer thickness," make the DOE table. The modulus of rupture and compression strength are responses to analyze the influence of significant parameters on the performance of a printed part. The results of X-ray tomography assist to offer a firm interpretation for the influence of each individual factor. Dimensional accuracy will be assessed by printing a benchmark with core and shells.
Selected parameters are variables in this technology determine water to cement ratio, therefore results aid to optimize the designed waveform and other two factors. Final properties of produced cement-based materials will be formulated as its printing parameter.