This Proceedings of the Sixth Solid Freeform Fabrication (SFF) Symposium, held at The
University of Texas in Austin on August 7-9, 1995, was attended by over 150 national and
international researchers. Papers addressed SFF issues in computer software, machine design,
materials synthesis and processing, and integrated manufacturing. The continued growth in the
research, application and development of SFF approaches was readily apparent from the increased
participation over previous years and the diverse domestic and foreign attendees from industrial
users, SFF machine manufacturers, universities, and government. The excitement generated at the
Symposium reflects the participants' total involvement in SFF and the future technical health of this
growing technology. The Symposium organizers look forward to its being a continuing forum for
technical exchange among the expanding body of researchers involved in SFF.
The Symposium was again organized in a manner to allow the multi-disciplinary nature of
the SFF research to be presented coherently, with various sessions emphasizing computer issues,
machine topics, and the variety of materials aspects of SFF. To avoid parallel sessions, a poster
session was organized. We believe that documenting the constantly changing state of SFF art as
represented by these Proceedings will serve both the people presently involved in this fruitful area
as well as the large flux of new researchers and users entering the field.
Several important issues surfaced during a plenary discussion at the end of the meeting.
Considerable interest was expressed in the availability of related topics on the worldwide web. In
response, The University of Texas at Austin Laboratory for Freeform Fabrication homepage
(http://shimano.me.utexas.edu/sffl) now includes links to all sites currently published by our home
page, including all locations submitted at the meeting. This current list of web locations is also
included at the end of this proceedings volume. We will be pleased to update the list by notification
of one of the Symposium Proceedings editors.
Another issue which would benefit a majority of SFF researchers is formation of a research
infrastructure manufacturing network. Interest was expressed in the formation of a library of
"public domain" .STL files. Clemson University has created this, and Elaine Persall is the contact
person. contact information is in the participant index.
The editors would like to extend a warm "Thank You" to Sue Ferentinos for her detailed
handling of the logistics of the meeting and the Proceedings, as well as her excellent performance
as registrar and problem solver during the meeting. We also acknowledge the support efforts of
Vicki Lehmeier and Cindy Pflughoft throughout. We would like to thank the organizing
committee, the session chairmen, the attendees for their enthusiastic contributions, and the speakers
both for their significant contribution to the meeting and for the relatively prompt delivery of the
manuscripts comprising this volume. We look forward to the continued close cooperation of the
SFF community in organizing the Symposium. We also want to thank ONR through Grant No.
N00014-95-1-0424, ARPA, and The Minerals, Metals and Materials Society for co-sponsoring the
Symposium with the Mechanical Engineering Department and the Center for Materials Science and
Engineering at the University of Texas at Austin.
Organizing Committee: Dick Aubin, United Technologies Research Center;
Joel W. 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;
Michael Cima, Massachusetts Institute of Technology;
William Coblenz, ARPA;
Richard Crawford, The University of Texas at Austin;
Samuel Drake, University of Utah;
Steven Fishman, Office of Naval Research;
Harris L. Marcus, University of Connecticut at Storrs;
Sean O'Reilly, Ford Motor Company;
Fritz Prinz, Stanford University;
Emanuel Sachs, Massachusetts Institute of Technology;
Greg Sanders, Lost Foam International;
Susan Smyth, General Motors Corporation;
Ralph Wachter, Office of Naval Research;
Michael Wozny, Nat'l Institute of Standards and TechnoIogy
Browsing 1995 International Solid Freeform Fabrication Symposium by Title
A versatile, automated, laser-based system, capable of producing complex threedimensional
shapes of ceramic and ceramic composite materials, through either controlled layer
ablation or solid freeform fabrication, is currently under development. The system comprises
a 1.2 kW C021aser, positioning system, beam scanner, non-contacting positioning sensor, beam
conditioner and CAD/CAM system. This paper reports progress in relating machine parameters
(scan rate, feed, beam power and polarization) to process measurables (material removal rate
and surface roughness), and demonstrates the potential for rapid prototyping and direct
manufacturing of: (a) rotationally symmetric components based on ablative ceramics such as
Si3N4 and (b) graphite fuel cell plenums
Many of the currently available RP-Systems are suitable for building design models of
arbitrarily shaped parts. However, most of these RP processes use sophisticated and expensive
equipment which is not well suited for an office environment. In this paper we present a
method and an experimental device for building design models by a modified 3D print process
using plastic powder and a photopolymeric binder.
The work shows the mechanical properties of direct laser-sintered metal parts. The parts were tested after sintering and after an infiltration. Furthermore the accuracy of the parts was measured. Micrographs of the parts show the microstructure of the copper-nicker-tin alloy. The achievable complexity of parts is demonstrated by examples. An overview of future activities is given.
(1995) Pang, Thomas H.; Guertin, Michelle D.; Nguyen, Hop D.
Rapid Prototyping and Manufacturing (RP&M) users need to compare the accuracy of various
commercially available RP&M materials and processes. A good diagnostic test for both material and the
fabrication process involves a 4-inch long "letter-H" diagnostic part. This diagnostic part, known as "H-4", was
developed to measure the inherent dimensional characteristics ofvarious RP&M build materials. It is also less
dependent on the calibration status of particular RP&M machines, and is excellent for the purpose of generating
simple but meaningful accuracy information, which can be used to further understand the mechanism and the
modes of distortion in RP&M materials. H-4 parts were prepared and built in Stereolithography Apparatus (SLA)
using Ciba-Geigy epoxy based resins SL 5170 and SL 5180, and results were compared to acrylate based SL 5149.
Experimental data involving the magnitude, mechanism, and the modes of distortion for these three resins are
analyzed in this paper.
The concept of CAM-LEM technology is presented and discussed in the context of the fabrication of Al2O3 ceramics. Particular attention is paid to the interplay of green tape characteristics and the unit operations involved in CAM-LEM. Examples of ceramic shapes
difficult to form by conventional methods are described.
This paper reports a radical departure from generally accepted concepts in construction
automation and demonstrates that new techniques of layered manufacturing can be applied
effectively to construction. In the process, we also modified material processing of cement to
adapt it to the requirements ofSolid Freeform Fabrication.
Our purpose is illustrated with sample structures manufactured by incremental deposition of
reactive bulk materials (cement and Silica in this instance), a characterization of their material
properties, and an assessment of their potential for Solid Freeform Fabrication of large structures.
For example, we estimated that it would take about months to build a structure the size
ofa 3000 sq. ft. house.
Free form fabrication methods have a great potential to significantly
improve the design and manufacture of equipment for people
with physical disabilities, such as quadriplegia through spinal cord injury,
arthrogryposis, or cerebral palsy. Depending on the nature of
the disability a device may need to be designed or adapted. A person
with quadriplegia, for example, may benefit from an assistive device
that maps existing head movements, into the movements of a spoon
between a plate and his/her mouth. To be comfortable and effective
a person Iuay need a headband that can connect to a suitable linkage.
Stereolithography lends itself well to the fabrication of such one-of-akind
devices. Since the fabrication process time is considerably less
than conventional approaches a greater number of iterations can be
performed during the design to arrive at the most compatible device
for a particular disability. Some rehabilitation devices are fabricated
to establish the viability and linlitations of this approach. This paper
details the efforts underway to integrate stereolithography with the
needs of rehabilitation engineering.
(1995) Mathewson, Brian B.; Newman, Wyatt S.; Heuer, Arthur H.; Cawley, James D.
This paper describes a machine and process for automated fabrication of functional 3-D
laminated engineering components, ceramics in the present example. A laser cuts successive layers
of a part derived from a CAD model description out of unfired tape-cast ceramic sheets
vacuum-clamped to an x-y sled. A material-handling robot uses a selective-area gripper to extract
only the desired part outlines from the surrounding waste material, then stacks the slices to build the
part. This system design enables rapid manufacture of functional engineering components with
arbitrarily complex internal and external geometries from virtually any material available in sheet
Current methods ofjoining of ceramic components may compromise the strength, chemical
resistance, or high temperature properties of the resulting ceramic parts. A new method of
joining, Ceramic Joining by Selective Beam Deposition, creates an all-ceramic joint
between two or more ceramic components through selective decomposition of a gas
precursor. An all-ceramic joint not only preserves the valuable properties of the ceramic
materials joined, but may be tailored to match the coefficient of thermal expansion ofthe
original material(s). The added material may be the same as one or both of the joined
Inaterials, or may be a composite material. This preliminary work explores the effect of
scanning speed and precursor pressure on Selective Beam Deposition ofsilicon carbide