Direct Three-Dimensional Layer Metal Deposition

2010 ◽  
Vol 132 (6) ◽  
Author(s):  
Jianzhong Ruan ◽  
Lie Tang ◽  
Frank W. Liou ◽  
Robert G. Landers
Keyword(s):  
Solid Freeform Fabrication ◽  
Experimental Studies ◽  
Three Dimensional ◽  
Deposition Method ◽  
Freeform Fabrication ◽  
Manufacturing Efficiency ◽  
Layer Deposition ◽  
Staircase Effect ◽  
Parallel Layer ◽  
Nonuniform Thickness

Multi-axis slicing for solid freeform fabrication manufacturing processes can yield nonuniform thickness layers or three-dimensional (3D) layers. The traditional parallel layer construction approach to building such layers leads to the so-called staircase effect, which requires machining or other postprocessing to form the desired shape. This paper presents a direct 3D layer deposition approach that uses an empirical model to predict the layer thickness. The toolpath between layers is not parallel; instead, it follows the final shape of the designed geometry and the distance between the toolpath in the adjacent layers varies at different locations. Directly depositing 3D layers not only eliminates the staircase effect but also improves manufacturing efficiency by shortening the deposition and machining times. Simulation and experimental studies are conducted that demonstrate these advantages. Thus, the 3D deposition method is a beneficial addition to the traditional parallel deposition method.

Direct 3D Layer Metal Deposition and Toolpath Generation

2008 ◽  
Author(s):  
Jianzhong Ruan ◽  
Lie Tang ◽  
Todd E. Sparks ◽  
Robert G. Landers ◽  
Frank Liou
Keyword(s):  
Solid Freeform Fabrication ◽  
Deposition Method ◽  
Single Track ◽  
Uniform Thickness ◽  
Post Processing ◽  
Freeform Fabrication ◽  
Manufacturing Efficiency ◽  
Layer Deposition ◽  
Staircase Effect ◽  
Parallel Layer

Multi-axis slicing for solid freeform fabrication (SFF) manufacturing process can yield non-uniform thickness layers, or 3-D layers. Using the traditional parallel layer construction approach to build such a layer leads to a staircase which requires machining or other post processing to form the desired shape. This paper presents a direct 3-D layer deposition approach. This approach uses an empirical model to predict the layer thickness based on experimental data. The toolpath between layers is not parallel; instead, it follows the final shape of the designed geometry and the distance between the toolpath in the adjacent layers varies at different locations. Directly depositing a 3-D layer not only eliminates the staircase effect, but also improves the manufacturing efficiency by shortening the deposition and machining times. A single track deposition experiment has demonstrated these advantages. Thus, it is a beneficial addition to the traditional parallel deposition method.

Modeling of Spatially Controlled Biomolecules in Three-Dimensional Porous Alginate Structures

2010 ◽  
Vol 4 (4) ◽  
Author(s):  
Ibrahim T. Ozbolat ◽  
Bahattin Koc
Keyword(s):  
Computer Aided Design ◽  
Solid Freeform Fabrication ◽  
Imaging Techniques ◽  
Release Kinetics ◽  
Three Dimensional ◽  
Control Release ◽  
Stochastic Approach ◽  
Distribution Characteristics ◽  
Porous Structures ◽  
Freeform Fabrication

This paper presents a computer-aided design (CAD) of 3D porous tissue scaffolds with spatial control of encapsulated biomolecule distributions. A localized control of encapsulated biomolecule distribution over 3D structures is proposed to control release kinetics spatially for tissue engineering and drug release. Imaging techniques are applied to explore distribution of microspheres over porous structures. Using microspheres in this study represents a framework for modeling the distribution characteristics of encapsulated proteins, growth factors, cells, and drugs. A quantification study is then performed to assure microsphere variation over various structures under imaging analysis. The obtained distribution characteristics are mimicked by the developed stochastic modeling study of microsphere distribution over 3D engineered freeform structures. Based on the stochastic approach, 3D porous structures are modeled and designed in CAD. Modeling of microsphere and encapsulating biomaterial distribution in this work helps develop comprehensive modeling of biomolecule release kinetics for further research. A novel multichamber single nozzle solid freeform fabrication technique is utilized to fabricate sample structures. The presented methods are implemented and illustrative examples are presented in this paper.

A Computational Design Framework for a Rapid Solid Freeform Fabrication Process

2000 ◽  
Author(s):  
Deepesh Khandelwal ◽  
T. Kesavadas
Keyword(s):  
Solid Freeform Fabrication ◽  
Optimization Technique ◽  
Three Dimensional ◽  
Computational Design ◽  
Freeform Fabrication ◽  
3D Cad ◽  
Build Time ◽  
Cad Models ◽  
Efficient Machine ◽  
Novel Concept

Abstract Solid Freeform Fabrication (SFF) techniques in recent years have shown tremendous promise in reducing the design time of products. This technique enables designers to get three-dimensional physical prototypes from 3D CAD models. Although SFF has gained popularity, the manufacturing time and cost have limited its use to small and medium sized parts. In this paper we have proposed a novel concept for rapidly building SFF parts by inserting prefabricated inserts into the fabricated part. A computational algorithm was developed for determining ideal placement of inserts/cores in the CAD model of the part being prototyped using a heuristic optimization technique called Simulated Annealing. This approach will also allow the designers to build multi-material prototypes using the Rapid Prototyping (RP) technique. By using cheaper pre-fabricates instead of costly photopolymers, the production cost of the SFFs can be reduced. Additionally it will also reduce build time, resulting in efficient machine utilization.

Direct Freeform Fabrication Technique for Bio-Manufacturing of Pre-Seeded, Spatially Heterogeneous, Anatomically-Shaped Alginate Hydrogel Implants

2005 ◽  
Author(s):  
Daniel L. Cohen ◽  
Evan Malone ◽  
Hod Lipson ◽  
Lawrence J. Bonassar
Keyword(s):  
Tissue Engineering ◽  
Solid Freeform Fabrication ◽  
Crosslinking Agent ◽  
Three Dimensional ◽  
Patient Specific ◽  
Efficient Production ◽  
Alginate Hydrogel ◽  
Freeform Fabrication ◽  
Patient Specific Implants ◽  
Multiple Material

A major challenge in orthopaedic tissue engineering is the generation of cell-seeded implants with structures that mimic native tissue, both in terms of anatomic geometries and intratissue cell distributions. By combining the strengths of injection molding tissue engineering with those of Solid Freeform Fabrication (SFF), three-dimensional pre-seeded implants were fabricated without custom-tooling, enabling efficient production of patient-specific implants. The incorporation of SFF technology also enables the fabrication of geometrically complex, multiple-material implants with spatially heterogeneous cell distributions that could not otherwise be produced. Using a custom-built robotic SFF platform and gel deposition tools, alginate hydrogel was used with calcium sulfate as a crosslinking agent to produce pre-seeded living implants of arbitrary geometries. The process was determined to be sterile and viable at 94±5%. The GAG production was found to be about half that of a similarly molded samples. The compressive elastic modulus was determined to be 1.462±0.113 kPa.

Development of HA-PLGA Scaffold Encapsulating Intact BMP-2 Using Solid Freeform Fabrication Technology

2011 ◽  
Author(s):  
Jin-Hyung Shim ◽  
Jong Young Kim ◽  
Kyung Shin Kang ◽  
Jung Kyu Park ◽  
Sei Kwang Hahn ◽  
...  
Keyword(s):  
Tissue Engineering ◽  
Bone Regeneration ◽  
Porous Scaffold ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
Porous Scaffolds ◽  
Prolonged Release ◽  
Cellular Activity ◽  
Freeform Fabrication

Tissue engineering is an interdisciplinary field that focuses on restoring and repairing tissues or organs. Cells, scaffolds, and biomolecules are recognized as three main components of tissue engineering. Solid freeform fabrication (SFF) technology is required to fabricate three-dimensional (3D) porous scaffolds to provide a 3D environment for cellular activity. SFF technology is especially advantageous for achieving a fully interconnected, porous scaffold. Bone morphogenic protein-2 (BMP-2), an important biomolecule, is widely used in bone tissue engineering to enhance bone regeneration activity. However, methods for the direct incorporation of intact BMP-2 within 3D scaffolds are rare. In this work, 3D porous scaffolds with poly(lactic-co-glycolic acid) chemically grafted hyaluronic acid (HA-PLGA), in which intact BMP-2 was directly encapsulated, were successfully fabricated using SFF technology. BMP-2 was previously protected by poly(ethylene glycol) (PEG), and the BMP-2/PEG complex was incorporated in HA-PLGA using an organic solvent. The HAPLGA/PEG/BMP-2 mixture was dissolved in chloroform and deposited via a multi-head deposition system (MHDS), one type of SFF technology, to fabricate a scaffold for tissue engineering. An additional air blower system and suction were installed in the MHDS for the solvent-based fabrication method. An in vitro evaluation of BMP-2 release was conducted, and prolonged release of intact BMP-2, for up to 28 days, was confirmed. After confirmation of advanced proliferation of pre osteoblasts, a superior differentiation effect of the HA-PLGA/PEG/BMP-2 scaffold was validated by measuring high expression levels of bone-specific markers, such as alkaline phosphatase (ALP) and osteocalcin (OC). We show that our solvent-based fabrication is a non-toxic method for restoring cellular activity. Moreover, the HAPLGA/PEG/BMP-2 scaffold was effective for bone regeneration.

A Novel Three-Dimensional Direct Controlled Cell Assembling System

2013 ◽  
Vol 652-654 ◽  
pp. 2079-2085
Author(s):  
Yu Li ◽  
Lei Zhang ◽  
Chang Yong Liu ◽  
Yu Zhao ◽  
Wei Sun
Keyword(s):  
Experimental Study ◽  
Modular Design ◽  
Design Method ◽  
Solid Freeform Fabrication ◽  
Three Dimensional ◽  
Freeform Fabrication ◽  
Heterogeneous Object ◽  
Continuous Deposition ◽  
Deposition Mode ◽  
Cell Assembling

Solid freeform fabrication (SFF) technology has been widely used to fabricate three-dimensional (3D) cell constructs. As multi-cell construct is a heterogeneous object (He-Object), it is a trend of biomanufacturing to use SFF technology to fabricate multi-cell constructs. In this paper, a novel multi-nozzle deposition system, called as 3D direct controlled cell assembling (CA) system, was developed to fabricate 3D multi-cell constructs. The developed system design was demand-oriented and applied functional modular design method. As the key part of this system, the multi-nozzle system was designed and described in details. Experimental study was conducted and results showed that the system could meet the requirements of the process and be used to fabricate complex 3D cell constructs. By comparison, the developed system could precisely deposite biomaterials with high viscocity and form constructs with big size in continuous deposition mode.

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