Positive pressure drop-on-demand printhead for Three-Dimensional Printing

In drop-on-demand printing, wetting out of the binder fluid onto the orifice face typically has been prevented by some combination of the following: coatings on the orifice face, high surface energy fluids, and negative pressure. This non-wetting approach is not practical for low surface energy fluids. A new positive pressure method of drop-on-demand printing has been developed which eliminates the requirement for a non-wetting system; modifications to the binder fluid properties or to the orifice material to ensure non-wetting are no longer necessary for reliable drop formation. In fact, slight positive pressure (relative to atmosphere) is maintained in the binder fluid at the orifice to achieve intentional wetting of a small area around the orifice. The pressure causes the binder meniscus to bulge out from the orifice until it detaches from the orifice edge and wets the orifice face. The binder wetting continues outward from the orifice edge along the plane of the orifice face, and would continue uncontrolled were it not for an additional constraint: the orifice face ends abruptly with a sharp corner to which the meniscus attaches, thus defining the wetting boundary for the binder. With such a boundary in place, the fluid meniscus forms a spherical cap on the orifice face. The thickness of the cap can be varied by adjusting the level of positive pressure. Benefits of this controlled wetting include successful drop-on-demand printing with low surface energy fluids, including ethanol and chloroform, and also successful drop formation using polymer-loaded binder without the build-up of solid polymer deposits at the orifice.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Gleason, Blake Wilbur

Advisor dc:contributor.advisor

• Emanuel M. Sachs.

• Mechanical Engineering.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/32318

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/32318