The Twenty-First Annual International Solid Freeform Fabrication (SFF) Symposium – An
Additive Manufacturing Conference, held at The University of Texas in Austin on August 9-11,
2010, was attended by almost 150 researchers from 11 countries. Papers addressed additive
manufacturing issues in computer software, machine design, materials synthesis and processing,
and integrated manufacturing. The diverse domestic and foreign attendees included industrial users,
machine manufacturers, university researchers and representatives from the government.
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 process development,
modeling, applications and materials. We believe that documenting the changing state of the art in
additive manufacturing through this Proceedings will serve both those presently involved in this
fruitful technical area as well as new researchers and users entering the field.
A special session on government issues in additive manufacturing was held Monday morning.
Participants discussed various aspects of additive manufacturing from the perspectives of users,
funding agencies, standards producers and customers. Speakers were William Frazier (NAVAIR),
Karen Taminger (NASA Langley), Mary Kinsella (AFRL) and Albert Wavering (NIST).
This year’s best oral presentation was given by Adriaan Spierings, Nikolaus Herres and Gideon
Levy from inspire AG, St.Gallen, Switzerland and the Hochschule für Technik Buchs, Switzerland.
Selection is based on the overall quality of the paper, the presentation and discussion at the meeting,
the significance of the work and the manuscript submitted to the proceedings. The paper title was,
"Influence of the Particle Size Distribution on Surface Quality and Mechanical Properties in
Additive Manufactured Stainless Steel Parts". Selected from 88 oral presentations, this presentation
appears on Page 397 of this Proceedings. The best poster presentation selected from 22 posters was
given by Shyam Barua, Todd Sparks and Frank Liou from the Missouri University of Science
and Technology. The paper title was, "Development of a Low Cost Imaging System for a Laser
Metal Deposition Process" and appears on Page 121.
This is the second year we have presented awards recognizing an outstanding junior and senior
researcher in the field of additive manufacturing. The recipient of the International Outstanding
Young Researcher in Freeform and Additive Manufacturing Award was Dr. Peter Mercelis,
Managing Director of LayerWise, NV in Belgium. Dr. Gideon Levy, Research Manager and Head
of the Institute for Rapid Product Development at iRPD-Inspire AG in St. Gallen, Switzerland, won
the International Freeform and Additive Manufacturing Excellence (FAME) Award.
The editors would like to extend a warm “Thank You” to Rosalie Foster 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 would like to thank the Organizing Committee, the
session chairs, 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 the Office of Naval Research
(N00014-10-1-0528) and the National Science Foundation (#CMMI-1028881) for supporting this
meeting financially. The meeting was co-organized by the University of Connecticut at Storrs, and
the Mechanical Engineering Department and the Laboratory for Freeform Fabrication at The
University of Texas at Austin.
(University of Texas at Austin, 2010-09-23) Huang, T.S.; Doiphode, N.D.; Rahaman, M.N.; Leu, M.C.; Bal, B.S.; Day, D.E.
There is an increasing demand for synthetic scaffolds with the requisite biocompatibility,
internal architecture, and mechanical properties for the bone repair and regeneration. In this work,
scaffolds of a silicate bioactive glass (13-93) were prepared by a freeze extrusion fabrication
(FEF) method and evaluated in vitro for potential applications in bone repair and regeneration.
The process parameters for FEF production of scaffolds with the requisite microstructural
characteristics, as well as the mechanical and cell culture response of the scaffolds were
evaluated. After binder burnout and sintering (60 min at 700°C), the scaffolds consisted of a
dense glass network with interpenetrating pores (porosity ≈ 50%; pore width = 100−500 µm).
These scaffolds had a compressive strength of 140 ± 70 MPa, which is comparable to the
strength of human cortical bone and far higher than the strengths of bioactive glass and ceramic
scaffolds prepared by more conventional methods. The scaffolds also supported the proliferation
of osteogenic MLO-A5 cells, indicating their biocompatibility. Potential application of these
scaffolds in the repair and regeneration of load-bearing bones, such as segmental defects in long
bones, is discussed.
(University of Texas at Austin, 2010-09-23) Bernardo, Jesse; Samavedi, Satyavrata; Williams, Christopher B.; Morgan, Abby W.
Unlike traditional stochastic scaffold fabrication techniques, additive manufacturing (AM) can be used to create
tissue-specific three-dimensional scaffolds with controlled porosity and pore geometry. Directly fabricating
scaffolds through AM methods is limited because of the relatively few biocompatible materials available for
processing in AM machines. To alleviate these material limitations, an indirect fabrication method is proposed.
Specifically, the authors investigate the use of Fused Deposition Modeling to fabricate scaffold patterns of varied
pore size and geometry. The scaffold patterns are then mineralized with a biocompatible ceramic (hydroxyapatite).
A heat treatment is then used to pyrolyze the pattern and to sinter the thin ceramic coating. The result is a
biocompatible ceramic scaffold composed of hollow tubes, which may promote attachment of endothelial cells and
In this paper, the authors explore the scaffold pattern fabrication and mineralization processes. Two scaffold
pattern materials are tested [acrylonitrile butadiene styrene (ABS) and investment cast wax (ICW)] to determine
which material is the most appropriate for scaffold mineralization and sintering. While the ICW could not be
thoroughly mineralized despite a sodium hydroxide surface treatment, the ABS patterns were successfully
mineralized following an oxygen plasma surface treatment. A 0.004 mm mineral coating was found on the ABS
patterns that featured a strut offset of 0.3 mm, which is in the range of appropriate pore size for bone tissue
(University of Texas at Austin, 2010-09-23) Hoeges, S.; Lindner, M.; Meiners, W.; Smeets, R.
Using bioresorbable materials implants can be manufactured which dissolve in the human body
and are replaced by natural bone structure. For large implants an interconnecting porous structure
needs to be integrated in the implant for a good vascularisation. Using additive manufacturing
technology these internal structures can be directly manufactured. The structure can be designed
by consequent following the guidelines of the medical expert. This paper describes the development of Selective Laser Melting to process bioresorbable materials Poly(D,L-lactide) and B-Tricalciumphosphate. The properties of the parts concerning microstructure, mechanical and
biological properties after processing are analyzed in laboratory and animal tests. Possible
applications are demonstrated and include individual bone substitute implants in cranio-maxillofacial surgery.
(University of Texas at Austin, 2010) George, Mitchell J.; Crawford, Richard H.
Selective Laser Sintering (SLS) is a manufacturing process that can build arbitrarily shaped parts
without part specific tooling. Its advantages have been employed in many different fields, one of
these being medical surgery. Currently, SLS is limited in medical applications as a pre-operative
modeling tool. For SLS manufacturing to progress in areas like compliant surgical tooling and
patient specific bone matrices, concurrent work is needed to investigate the effects of medical
sterilization on SLS materials. This paper presents the results of sterilization experiments on SLS
parts built from nylon 11. To simulate the process of introducing tools into a sterile environment,
these specimens were subjected to multiple rounds of dry heat sterilization. Changes to the
dimensions, tensile strength and flexibility were recorded and analyzed. It was found that the
specimens’ dimensions remained relatively constant. Both the tensile modulus and the flexural
modulus decreased as the sterilization cycles progressed. The tensile modulus decreased by 25%
and the flexure modulus decreased by 19% after ten rounds of sterilization.
(2010) Wang, Wanshan; Wu, Wenzheng; Yu, Tianbiao; Qin, Xingjun; Chen, Yadong; Rosen, David W.
The usage of RP models can shorten the operation time for reconstructive surgery of mandible
defects using the free fibula flap technique and can improve the accuracy of mandible
reconstruction. This paper reports on a case study of reconstructive surgery on a patient with a
mandibular defect caused by a tumor. A customized mandible rapid prototype model was
manufactured from the patient’s CT data and was used to simulate the reconstructive surgery
procedure. A customized titanium plate was shaped using the mandible RP model as a pattern
before surgery. The usage of a mandible RP model reduced the operation time by 1.5-2.5 hours
and the shape precision of the reconstructed mandible was improved. The customized titanium
plate was consistent with the mandible anatomy.
(2010) Kolan, Krishna C.R.; Doiphode, Nikhil D.; Leu, Ming C.
13-93 glass is a third-generation bioactive material which accelerates the bone’s natural ability to
heal by itself through bonding with surrounding tissues. It is an important requirement for
synthetic scaffolds to maintain their bioactivity and mechanical strength with a porous internal
architecture comparable to that of a human bone. Additive manufacturing technologies provide a
better control over design and fabrication of porous structures than conventional methods. In this
paper, we discuss and compare some of the common aspects in the scaffold fabrication using two
such processes, viz. selective laser sintering (SLS) and freeze extrusion fabrication (FEF).
Scaffolds fabricated using each process were structurally characterized and microstructure
analysis was performed to study process differences. Compressive strength higher than that of
human trabecular bone was achieved using SLS process and strength almost comparable to that
of human cortical bone was achieved using FEF process.
(2010-09-23) Horn, Timothy J.; Harrysson, Ola L.A.; Little, Jeffrey P.; West, Harvey A. Jr; Marcellin-Little, Denis J.
The performance of orthopedic implants is often evaluated using cadaveric bone
specimens. The high inter-specimen variability of cadaveric bone properties requires large
sample sizes to obtain statistical significance. With recent focus on custom implants
manufactured using direct metal freeform fabrication techniques, the need for a customized bone
analog model is recognized. Data for bone geometry and internal structure were obtained from
computed-tomography imaging. Traditional rapid prototyping techniques are then used to
generate the rapid tooling from which composite bones that mimic the properties of the real bone
can be duplicated. This work focused on the manufacturing process of bone analog models.
(2010) Frank, Matthew C.; Joshi, Ashish; Anderson, Donald D.; Thomas, Thaddeus P.; Rudert, M. James; Tochigi, Yuki; Marsh, J. Lawrence; Brown, Thomas D.
This research involves the development of rapid manufacturing for patient-specific bone implants
using a Subtractive Rapid Prototyping process. The geometry of segmental defects in bone, resulting
from traumatic injury or cancerous tumor resection, can be reverse-engineered from medical images (such
as CT scans), and then accurate defect fillers can be automatically generated in advanced synthetic or
otherwise bioactive/biocompatible materials. This paper presents a general process planning
methodology that begins with CT imaging and results in the automatic generation of process plans for a
subtractive RP system. This work uniquely enables the rapid manufacturing of implant fillers with
several key characteristics including; suitable bio-compatible materials and custom surface characteristics
on specified patches of the filler geometry. This work utilizes a PLY input file, instead of the more
common STL, since color texture information can be utilized for advanced process planning depending
on whether the surface is fracture, periosteal or articular in origin. The future impact of this work is the
ability to create accurate filler geometries that improve initial fixation strength and stability through
accurate mating geometry, fixation planning and inter-surface roughness conditions.
Keywords: Rapid Machining, Rapid Prototyping, Bone Implants, Surface Texturing
Recently, a new technique has been developed to create unique open-cellular materials with
micro-scale truss, or lattice features ranging from tens to hundreds of microns. These materials
are formed from a three-dimensional, interconnected array of self-propagating photopolymer
waveguides. By utilizing this self-propagating effect, three-dimensional open-cellular polymer
materials can be formed in seconds. In addition, intrinsic to the process is the ability to control
specific micro-lattice parameters which ultimately affect the bulk material properties. Unlike
stereolithography, this new fabrication technique is rapid (~ minutes to form an entire part) and
relies on a single two-dimensional exposure surface to form three-dimensional structures
(thickness > 25 mm possible). This combination of speed and planar scalability opens the
possibility for large-scale mass manufacturing. The utility of these new materials range from
lightweight energy absorbing structures to thermal management materials to bio-scaffolds.