Design of a slurry layer forming station and improved fluid handling system for raster processes in 3DP®

Three-Dimensional Printing (3DPTM) is a rapid-manufacturing process originally developed at MIT for building parts directly from CAD-generated models. Parts are fabricated in "slices" by creating a complete layer of powder and then selectively joining powder particles with a polymer binder deposited using a moving printhead. Traditional 3DPTM builds layers by spreading dry powder and prints binder using a rastering scheme with a continuous-jet printhead. For smaller parts and greater accuracy, a variation on the process called slurry 3DPTM (s3DPTM) uses raster-built slurry layers and a vector-printing scheme with a drop on demand (DoD) printhead. This here thesis presents efforts to improve core technology in both dry-powder 3DPTM and slurry 3DPTM. One of the most critical steps in s3DPTM is the building of the slurry layers. To avoid intra- and interlayer defects the slurry layer must be rastered at high deposition rates to promote line merging and better layer quality. The difficulty lies in the design of a machine capable of oscillating the slurry nozzle at the required frequencies. Fortunately, such a design was completed and the machine built as part of a collaborative effort with TDK Japan to build an s3DPTM machine for manufacturing small parts. The design uses a reciprocating countermass strategy to recycle mechanical energy and eliminate troublesome vibrations. A general overview of this slurry layer forming station (LFS) is given, along with an in-depth treatment of several components, including the forcers, centering system, and interface software. And speaking of rastering, dry-powder 3DPTM relies on this strategy for printing binder, just as the LFS uses a raster method to build powder layers. Beginning with observations made during the design of the LFS, the fluid-handling system was redesigned to improve binder droplet stream stability during the carriage traverse and turnaround. The improvement was made possible by repositioning a smaller version of the "Clamshell" constant pressure vessel used to set the fluid flow rate to the printhead carriage itself and using a closed-loop control system to maintain a constant fluid level in the Clamshell. Drawings, parts lists, schematic diagrams, and assembly instructions are included for building additional fluid control systems.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Mechanical Engineering.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2001

Author dc:creator

• Ables, David C. (David Christopher), 1973-

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/1721.1/8545

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/8545