Enhanced droplet volume of material jetting based on bipolar waveform optimization

Fiercer requirements are put forward for the droplet jetting efficiency with the increasing application demand of piezoelectric inkjet technique in additive manufacturing. However, the progress of existing studies on promoting droplet jetting efficiency is restricted by their difficulty in achieving large scale droplet volume increase, with the maximum droplet volume limited to about 8 times the native droplet volume. Herein, a new droplet volume enhancing method was proposed based on bipolar waveform optimization, in which a bottom-up modular optimization method was applied according to the superposition characteristics of flow field oscillation inside the piezoelectric printhead system. More importantly, this method focused on the multi-droplet merging characteristics driven by multi-pulse waveforms, with the aim of realizing significant increase in droplet volume. The experimental results have shown that the newly designed waveform achieves stable droplets with the maximum-to-native volume ratio above 50, i.e., nearly six times above current levels. Hence, this work contributes a new perspective to droplet jetting efficiency.