Droplet volume modulation based on multi-waveform superposition for drop-on-demand material jetting

The piezoelectric drop-on-demand material jetting technique is widely used in additive manufacturing due to its cost-effectiveness, high accuracy, and the ability to efficiently print a variety of materials. However, there is a conflict between the requirements related to printing productivity and printing quality, which is solved by the droplet volume modulation method. In recent years, a variety of inkjet technologies have been developed to control the droplet volume, but control was achieved only over a small range, with the ratio between the maximum and minimum volume approx. 10. In this paper, the advance droplet phenomenon was shown and its formation mechanism was determined through experiments and simulations. Based on the formation mechanism and the response characteristic of the piezoelectric printhead to the basic waveform, a droplet volume modulation method was proposed. The method was based on multi-waveform superposition and the aim was to achieve a larger volume range of droplet ejection. The experimental results have shown that the newly designed waveform results in a controllable and stable single droplet ejection in a volume range from 0.61 pl to 83.7 pl, with the ratio between the maximum and minimum volume more than 130, an order of magnitude above current levels. Hence, this work provides a new perspective for improving both the printing quality and printing productivity of additive manufacturing. © 2023 Elsevier B.V.