This Proceedings of the Third Solid Freeform Fabrication Symposium, held at
The University of Texas in Austin on August 3-5, 1992, again demonstrates the very
active interest in this fully integrated approach to design, materials processing, and
manufacturing. The active participation of speakers and attendees from industry that uses
SFF, SFF machine manufacturers, universities, and government gives a clear indication
of the importance that SFF in its many variants has in the future of manufacturing. As
SFF extends itself into structurally sound parts made of polymers, metals, ceramics and
their composites, the number of people and institutions involved will continue to grow
exponentially. The organizers look forward to this growth and the continued availability
of the Solid Freeform Fabrication Symposium to serve as a source of technical exchange
among the researchers involved in the area.
The Symposium was organized in a manner to allow the multi-disciplinary nature
of the SFF research to be presented coherently. To avoid parallel sessions a poster
session was organized. The initial session emphasized the computer interfacing required
for SFF. This was followed by a session associated with materials related research on
SFF. Two sessions were offered describing the latest techniques and modifications of
SFF. These sessions were highlighted by a spirited panel discussion led by Robert L.
Brown, Emanuel Sachs, and Joel Barlow, on "where is SFF going?" The final session
concentrated on machine issues in SFF. The written versions of the presented papers are
incorporated into these Proceedings. The editors would like to thank the speakers for
their prompt delivery of the manuscripts that allows the timely publication of these
Proceedings. The constantly changing state of the SFF art as represented by these
Proceedings will serve both the people presently involved in this fruitful area as well as
new researchers and users coming into Solid Freeform Fabrication.
The editors would also like to extend a warm thank you to Carolyn Medina for her
extensive efforts in the detailed handling of the logistics of the meeting and the
Proceedings. We would also like to thank the organizing committee, the speakers, the
session chairmen, panel members, and the attendees for their enthusiastic contributions.
We look forward to the continued close cooperation of the SFF community in organizing
the Symposium. We also want to thank ONR and DARPA for co-sponsoring the
Symposium and DTM Corporation for hosting the reception.
Organizing committee: Dick Aubin, United Technologies;
Joel Barlow, The University of Texas at Austin;
Joseph J. Beaman, The University of Texas at Austin;
David L. Bourell, The University of Texas at Austin;
Robert L. Brown, The Gillette Company;
William Coblenz, DARPA;
Richard Crawford, The University of Texas at Austin;
Samuel Drake, University of Utah;
Steven Fishman, Office of Naval Research;
Harris L. Marcus, The University of Texas at Austin;
Fritz Prinz, Carnegie Mellon University;
Emanuel Sachs, Massachusetts Institute of Technology;
Greg Sanders, General Motors Corporation;
Peter R. Sferro, Ford Motor Company;
Ralph Wachter, Office of Naval Research;
Michael Wozny, Rennselaer Polytechnic Institute
Before we begin a discussion of machine issues it is important that we categorize
exactly what we mean. There are differences between the design of a research piece of
equipment as compared to a commercial piece of equipment. A research piece of
equipment has to have the flexibility to demonstrate a success pattern. A commercial
piece of equipment, on the other hand, assumes that you have a stable platform and you
are now trying to assess how broad a success path you have (Figure 1). In fact, you are
trying to make that path as broad as possible so that the machine will not fail and will
always work the same way. This particular talk, and my expertise, is much more along
the lines of design of a research piece of equipment. What I will be talking about today
are machine issues associated with developing a success path in Solid Freeform
Fabrication. The machines we will be talking about have to have the flexibility to operate
in a wide variety of ways with a wide variety of experiments.
This paper outlines the use of
FDM to speed product design and
to streamline the manufacturing
Time compression, the ability to
quickly reduce the time it takes to
get new products to market, has
increased the pressure on all phases
of the manufacturing process.
Manufacturers must find and
implement time saving systems
without sacrificing quality.
Adaptive laminated machining is the fusion of slicing a solid model into layers and producing parts by CNC
milling machines. Unlike other solid freeform fabrication processes which create the part by addition of
material, adaptive laminated machining can create solid parts by selectively removing in layers. The
research issues and practical limitations on shape and manufacturability are thus different from other
processes. However, the biggest advantage is the ability to obtain a solid metal part such as a die or a
mold directly. In this paper, the concept of this technique, and initial results and parts produced in Clemson
will be presented. In addition, future research needs and issues will be discussed.
Rapid prototyping systems are based, almost exclusively on polymer, or paper materials.
The dimensions of the parts produced are limited by the volume of the processing area within
the machine, and parts tend to warp or distort due to shrinkage and lack of support. Also the
mechanical properties of the part are restricted to those of the processable materials and thus,
in many cases, required 'engineering properties' cannot be obtained
(1992) Beck, James E.; Prinz, Fritz B.; Siewiorek, Daniel P.; Weiss, Lee E.
A new technology for manufacturing mechatronics is described. The technique is based on recursive
masking and deposition of thermally sprayed materials. Using these methods, mechanical structures
can be created that embed and interconnect electronic components. This results in highly integrated
mechatronic devices. A simple, electromechanical artifact was designed and produced to assess the
feasibility of these techniques. The details and limitations of this project will be discussed. Areas of
future research are identified which are aimed at realizing the full potential of this emerging manufacturing
The STL de facto data exchange standard for Solid Freefonn F*brication represents
CAD models as a collection of unordered triangular planar facels. No topological
connectivity information is provided; hence the term "bucket of facet." Such topological
information can, however, be quite useful for performing model validity checking and
speeding subsequent processing operations such as model slicing. lfhis paper discusses
model topology and how to derive it given a collection of unordered tri,ngular facets which
represent a valid model.
(1992) Roberts, Floyd; Lomshek, David; Brower, William E.
The ability to perform in-flight rapid prototyping would be of great benefit to NASA in two ways.
First, repair parts could be fabricated from CAD designs beamed up from earth based laboratories which
might allow a failed experiment to proceed. The mission specialists themselves, under the creative
influence of space flight, might design a new part or tool and fabricate it on board in a matter of hours.
Second, with metal casting and ceramic sintering facilities on board, rapid prototyping would allow
manufacturing in space. This paper presents some test criteria for evaluating two of the rapid prototyping
techniques, stereolithography and fused deposition, in microgravity conditions. Effects of the variation
of head speed and strip width for the fused deposition process on the resulting mechanical properties are
presented. The mechanical strength of the polyamide test bars increased with both increasing head speed
and strip width. Increasing head speed would be desirable in microgravity applications.