The effects of nozzle defects on the behaviour of drops ejected from drop-on-demand print-heads were studied. Nozzles in two types of commercial print-heads were modified with two different micromachining techniques: focused ion beam (FIB) milling and pulsed laser micromachining. Nozzles were modified by producing single or multiple notches on their edges. The studies focused on the volume, speed and direction of travel of the drops. Fifteen different types of geometrical defects on 128 nozzles were studied. Shadowgraph images captured with short high time resolution were used to determine the drop size, speed and trajectory from the same nozzles before and after modification. The results indicate that geometrical defects up to ∼100 μm2 at the front (exit) face of a 50 μm diameter nozzle do not cause any significant variation on the behaviour of these nozzles but that defects at the back (entry) of the nozzle can have a major effect on the direction of jetting.
J.R. Castrejón-Pita, G.D. Martin, I. M. Hutchings, "Influence of Nozzle Defects on Drop-on-demand Ink-jets" in Proc. IS&T Int'l Conf. on Digital Printing Technologies and Digital Fabrication (NIP26), 2010, pp 14 - 17, https://doi.org/10.2352/ISSN.2169-4451.2010.26.1.art00005_1