Journal articles: 'Solid Freeform Fabrication (SFF)'

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Arni, Ramakrishna, and S. K. Gupta. "Manufacturability Analysis of Flatness Tolerances in Solid Freeform Fabrication." Journal of Mechanical Design 123, no. 1 (September 1, 1999): 148–56. http://dx.doi.org/10.1115/1.1326439.

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Increasingly, Solid Freeform Fabrication (SFF) processes are being considered for creating functional parts. In such applications, SFF can either be used for creating tooling (i.e., patterns for casting, low volume molds, etc.) or directly creating the functional part itself. In order to create defect free functional parts, it is extremely important to fabricate the parts within allowable dimensional and geometric tolerances. This paper describes a systematic approach to analyzing manufacturability of parts produced using SFF processes with flatness tolerance requirements on the planar faces of the part. Our research is expected to help SFF designers and process providers in the following ways. By evaluating design tolerances against a given process capability, it will help designers in eliminating manufacturing problems and selecting the right SFF process for the given design. It will help process providers in selecting a build direction that can meet all design tolerance requirements.

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Pinilla, Jose Miguel, Ju-Hsien Kao, and Fritz Prinz. "Compact graph representation for Solid Freeform Fabrication (SFF)." Journal of Manufacturing Systems 19, no. 5 (January 2001): 341–54. http://dx.doi.org/10.1016/s0278-6125(01)89006-3.

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Kakisawa, Hideki, Kazumi Minagawa, Keisuke Ida, Katsuhiro Maekawa, and Kohmei Halada. "Dense P/M Component Produced by Solid Freeform Fabrication (SFF)." MATERIALS TRANSACTIONS 46, no. 12 (2005): 2574–81. http://dx.doi.org/10.2320/matertrans.46.2574.

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Rogers, Bill, Gordon W. Bosker, Richard H. Crawford, Mario C. Faustini, Richard R. Neptune, Gail Walden, and Andrew J. Gitter. "Advanced Trans-Tibial Socket Fabrication Using Selective Laser Sintering." Prosthetics and Orthotics International 31, no. 1 (March 2007): 88–100. http://dx.doi.org/10.1080/03093640600983923.

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There have been a variety of efforts demonstrating the use of solid freeform fabrication (SFF) for prosthetic socket fabrication though there has been little effort in leveraging the strengths of the technology. SFF encompasses a class of technologies that can create three dimensional objects directly from a geometric database without specific tooling or human intervention. A real strength of SFF is that cost of fabrication is related to the volume of the part, not the part's complexity. For prosthetic socket fabrication this means that a sophisticated socket can be fabricated at essentially the same cost as a simple socket. Adding new features to a socket design becomes a function of software. The work at The University of Texas Health Science Center at San Antonio (UTHSCSA) and University of Texas at Austin (UTA) has concentrated on developing advanced sockets that incorporate structural features to increase comfort as well as built in fixtures to accommodate industry standard hardware. Selective laser sintering (SLS) was chosen as the SFF technology to use for socket fabrication as it was capable of fabricating sockets using materials appropriate for prosthetics. This paper details the development of SLS prosthetic socket fabrication techniques at UTHSCSA/UTA over a six-year period.

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Wu, Quan, Xiang Lin Zhang, and Meng Jun Li. "Research on Microwave Sintering Process for High Strength HA Porous Scaffold." Advanced Materials Research 239-242 (May 2011): 2515–19. http://dx.doi.org/10.4028/www.scientific.net/amr.239-242.2515.

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This paper investigated solid freeform fabrication(SFF) and microwave sintering processes of high strength HA porous scaffold. A newly developed SFF method called motor assisted micro-syringe freeform fabrication system was introduced to construct HA scaffolds. Sintering conditions that influenced the phases, microstructure and mechanical strength of scaffolds were discussed. Study of microstructure images and strength test results showed that densification and grain size were found to play an important role in determining the mechanical properties of sintered porous scaffolds, and microwave sintering process could get a sintered scaffold with small grain size and uniform structure more rapidly at lower sintering temperature than that of the conventional sintering. The fabricated HA scaffolds with controlled architecture (interconnected macro pore of 200-400μm, micro pore of 1-10μm within the rods) and improved mechanical properties (45.2MPa, 56.2% porosity ) may find potential applications in bone tissue engineering.

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KIM, DONG SOO, SUNG WOO BAE, and KYUNG HYUN CHOI. "APPLICATION AND PERFORMANCE EVALUATION FOR THE DMS SYSTEM IN THE SLS PROCESS." International Journal of Modern Physics B 22, no. 09n11 (April 30, 2008): 1833–38. http://dx.doi.org/10.1142/s0217979208047493.

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A Solid Freeform Fabrication (SFF) system using Selective Laser Sintering (SLS) is currently recognized as a leading process and SLS extends the applications to machinery and automobiles due to the various materials employed. Especially, accuracy and processing time are very important factors when the desired shape is fabricated with Selective Laser Sintering (SLS), one of Solid Freeform Fabrication (SFF) system. In the convectional SLS process, laser spot size is fixed during laser exposing on the sliced figure. Therefore, it is difficult to accuracy and rapidly fabricates the desired shape. In this paper, to deal with those problems a SFF system having ability of changing spot size is developed. The system provides high accuracy and optimal processing time. Specifically, a variable beam expander is employed to adjust spot size for different figures on a sliced shape. Therefore, design and performance estimation of the SFF system employing a variable beam expander are achieved and the mechanism will be addressed to measure the real spot size generated from the variable beam expander. Also, the reduction of total processing time is an important issue in SFF system. A digital mirror system (DMS) is a system which scans the laser beam with different spot size. The spot size is selected based on the slicing section to decrease and accuracy of the process time and improve the processing efficiency. In this study, the optimal scan path generation for DMS will be addressed, and this development will improve the whole processing efficiency and accuracy through the scan efficiency by considering the existing scan path algorithm and heat energy distribution.

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Heard, David W., Julien Boselli, Raynald Gauvin, and Mathieu Brochu. "Solid Freeform Fabrication of Al-Li 2199 via Controlled-Short-Circuit-MIG Welding." Advanced Materials Research 409 (November 2011): 843–48. http://dx.doi.org/10.4028/www.scientific.net/amr.409.843.

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Aluminum-lithium (Al-Li) alloys are of interest to the aerospace and aeronautical industries as rising fuel costs and increasing environmental restrictions are promoting reductions in vehicle weight. However, Al-Li alloys suffer from several issues during fusion welding processes including solute segregation and depletion. Solid freeform fabrication (SFF) of materials is a repair or rapid prototyping process, in which the deposited feedstock is built-up via a layering process to the required geometry. Recent developments have led to the investigation of SFF processes via Gas Metal Arc Welding (GMAW) capable of producing functional metallic components. A SFF process via GMAW would be instrumental in reducing costs associated with the production and repair of Al-Li components. Furthermore the newly developed Controlled-Short-Circuit-MIG (CSC-MIG) process provides the ability to control the weld parameters with a high degree of accuracy, thus enabling the optimization of the solidification parameters required to avoid solute depletion and segregation within an Al-Li alloy. The objective of this study is to develop the welding parameters required to avoid lithium depletion and segregation. In the present study weldments were produced via CSC-MIG process, using Al-Li 2199 sheet samples as the filler material. The residual lithium concentration within the weldments was then determined via Atomic Absorption (AA) and X-ray Photoelectron Spectroscopy (XPS). The microstructure was analyzed using High Resolution Scanning Electron Microscopy (HR-SEM). Finally the mechanical properties of welded samples were determined through the application of hardness and tensile testing.

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Chin, R. K., J. L. Beuth, and C. H. Amon. "Successive Deposition of Metals in Solid Freeform Fabrication Processes, Part 2: Thermomechanical Models of Adjacent Droplets." Journal of Manufacturing Science and Engineering 123, no. 4 (May 1, 2000): 632–38. http://dx.doi.org/10.1115/1.1380200.

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Residual stress-induced tolerance losses are a principal barrier for using Solid Freeform Fabrication (SFF) processes to create functional parts out of engineering materials. In Part 1 of this paper, problems of successively deposited layers and droplets deposited in a column are considered for SFF processes. Models of these problems are used to detail thermal and mechanical interactions between existing and newly deposited material as well as their effects on final residual stress distributions on sub-layer (droplet) and multi-layer scales. In the current study, sub-layer interactions are further considered using models of droplets deposited adjacent to one another. As in Part 1, models are applied to a particular SFF process; however, insights and conclusions are relevant to numerous similar SFF processes. Simulations of separated and connected droplets deposited onto a large substrate indicate very limited thermal interactions between adjacently deposited droplets. However, mechanical interactions between droplets can be significant, which is consistent with the directionality of warping observed in experiments. Results from deposition of droplets on a thin substrate demonstrate the importance of process-induced substrate preheating in reducing residual stresses.

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Lim, K. K., P. Cheang, and M. Chandrasekaran. "Studies on Porous Titanium Alloy Implant Manufactured by Three Dimensional Solid Freeform Fabrication System." Advanced Materials Research 29-30 (November 2007): 107–10. http://dx.doi.org/10.4028/www.scientific.net/amr.29-30.107.

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Titanium (Ti) alloys have emerged to become valuable biomaterials for biomedical and orthopedic applications due to their high strength to weight ratio, excellent biocompatibility and corrosion resistance. In this study, the authors utilized Solid Freeform Fabrication (SFF), also commonly known as a rapid prototyping technology to investigate a new porous three-dimensional (3D) Ti alloy implant. Elemental powders for producing a Ti-Al-Fe-Zr alloy were mechanically alloyed and blended with water soluble binder material. The blended powders were manufactured by Three Dimensional Printer (3DP), followed by debinding and sintering in an inert environment. The effects of process parameters on structural and geometrical requirements were assessed. Results from these investigations demonstrated that Ti alloys are promising biomaterials for near net shape fabrication of porous 3D implants, which retained their interconnected pore network. As an illustration, complex geometries of porous 3D Ti alloy specimens were manufactured as a demonstration of 3D SFF System.

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Hu, D., H. Mei, and R. Kovacevic. "Improving solid freeform fabrication by laser-based additive manufacturing." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 216, no. 9 (September 1, 2002): 1253–64. http://dx.doi.org/10.1243/095440502760291808.

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Solid freeform fabrication (SFF) methods for metal part building, such as three-dimensional laser cladding, are generally less stable and less repeatable than other rapid prototyping methods. A large number of parameters govern the three-dimensional laser cladding process. These parameters are sensitive to the environmental variations, and they also influence each other. This paper introduces the research work in Research Center for Advanced Manufacturing (RCAM) to improve the performance of its developed three-dimensional laser cladding process: laser-based additive manufacturing (LBAM). Metal powder delivery real-time sensing is studied to achieve a further controllable powder delivery that is the key technology to build a composite material or alloy with a functionally gradient distribution. An opto-electronic sensor is designed to sense the powder delivery rate in real time. The experimental results show that the sensor's output voltage has a good linear relationship with the powder delivery rate. A closed-loop control system is also built for heat input control in the LBAM process, based on infrared image sensing. A camera with a high frame rate (up to 800frame/s) is installed coaxially to the top of the laser—nozzle set-up. A full view of the infrared images of the molten pool can be acquired with a short nozzle—substrate distance in different scanning directions, eliminating the image noise from the metal powder. The closed-loop control results show a great improvement in the geometrical accuracy of the built feature.

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KIM, Dong Soo, Young Jin AHN, Won Hee LEE, Sung Woo BAE, and Kyung Hyun CHOI. "A Study of the Solid Freeform Fabrication (SFF) System with Dual Laser System." JSME International Journal Series C 49, no. 4 (2006): 1215–22. http://dx.doi.org/10.1299/jsmec.49.1215.

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Vasinonta, Aditad, Jack L. Beuth, and Michelle L. Griffith. "A Process Map for Consistent Build Conditions in the Solid Freeform Fabrication of Thin-Walled Structures." Journal of Manufacturing Science and Engineering 123, no. 4 (August 1, 2000): 615–22. http://dx.doi.org/10.1115/1.1370497.

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In solid freeform fabrication (SFF) processes involving thermal deposition, thermal control of the process is critical for obtaining consistent build conditions and in limiting residual stress-induced warping of parts. In this research, a nondimensionalized plot (termed a process map) is developed from numerical models of laser-based material deposition of thin-walled structures. This process map quantifies the effects of changes in wall height, laser power, deposition speed and part preheating on melt pool length, which is an essential process parameter to control in order to obtain consistent build conditions. The principal application of this work is to the Laser Engineered Net Shaping (LENS) process under development at Sandia Laboratories; however, the general approach and a subset of the presented results are applicable to any SFF process involving a moving heat source. Procedures are detailed for using the process map to predict melt pool length and predictions are compared against experimentally measured melt pool lengths for stainless steel deposition in the LENS process.

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Chin, R. K., J. L. Beuth, and C. H. Amon. "Successive Deposition of Metals in Solid Freeform Fabrication Processes, Part 1: Thermomechanical Models of Layers and Droplet Columns." Journal of Manufacturing Science and Engineering 123, no. 4 (May 1, 2000): 623–31. http://dx.doi.org/10.1115/1.1380199.

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Solid Freeform Fabrication (SFF) processes allow the automated building of three-dimensional shapes by successively depositing material in layers. Residual stress-induced tolerance losses are principal concerns in using these processes to create functional parts. Thermomechanical models of temperatures and stresses are presented, which are relevant to controlling residual stress effects in SFF processes. Models are applied to a particular SFF process; however, insights and conclusions are applicable to a large number of related processes. The temporal evolution of temperatures and stresses is investigated at two levels of detail. The successive deposition of layers of material is investigated first using one-dimensional simulations, approximating the build-up of residual stress in a multi-layered part. The successive deposition of a column of molten metal droplets (a technique used to create thick layers) is then modeled using two-dimensional axisymmetric simulations. Insights are given into process changes that can minimize residual stress-related effects in manufactured parts, including part constraint and localized preheating near the point of deposition. Results for thermomechanical interactions between droplets deposited in a column provide the foundation for studying interactions between adjacently deposited droplets, which is addressed in Part 2.

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Lafon, Jean Baptitse, Christophe Chaput, Richard Gaignon, and Cyrille Delage. "3D Net-Shape Manufacturing of Complex Ceramic Parts by High Resolution Stereo Lithography – Examples of Application to Biomedical and Industrial Products." Additional Conferences (Device Packaging, HiTEC, HiTEN, and CICMT) 2011, CICMT (September 1, 2011): 000261–65. http://dx.doi.org/10.4071/cicmt-2011-tha13.

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Solid Freeform Fabrication (SFF) processes are fairly new shaping methods, which allow the direct fabrication of complex ceramic structures, without tooling or machining, on the basis of a component CAD file. SFF techniques provide an attractive answer for applications with the need to produce custom designs while also controlling the product structure or producing multimaterial devices demanding improved properties or multifunctional components. Stereolithography (SL) is a layer manufacturing process based on the space-resolved polymerisation of a UV photocurable compound consisting in a dispersion of ceramic particles in a monomer containing a photoinitiator. Improvements in the SL process, notably understanding and driving the key parameters influencing the 3D resolution of the reactive compound, now make it possible to directly manufacture useful 3D ceramic parts with final properties similar or identical to those obtained from traditional processes. SL processing applications are numerous and include medical implants, complex microwave devices, refractory molds and cores, MEMS, microfluidic networks for micro reactors, drug delivery devices or biological analysis, etc...

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Lee, Won Hee, Dong Soo Kim, Young Jin Ahn, Byung Oh Choi, and Kyung Hyun Choi. "Development of Industrial SFF System Using a New Selective Dual-Laser Sintering Process." Key Engineering Materials 326-328 (December 2006): 123–26. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.123.

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In order to develop more elaborate and speedy system for large objects than existing selective laser sintering (SLS), this study applies a new selective dual-laser sintering process. It contains a 3-axis dynamic focusing scanner system for scanning large area instead of the existing fθ lens. As sintering parameters, the sintering temperature, the laser beam power and the layer thickness have a great influence on sintering of the polymer and metal powder. This paper will address the development of a solid freeform fabrication (SFF) system employing the dual laser system. Experiments were performed to evaluate the effect of a scanning path and to fabricate the large-sized object.

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Li, Yu, Lei Zhang, Chang Yong Liu, Yu Zhao, and Wei Sun. "A Novel Three-Dimensional Direct Controlled Cell Assembling System." Advanced Materials Research 652-654 (January 2013): 2079–85. http://dx.doi.org/10.4028/www.scientific.net/amr.652-654.2079.

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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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Rajagopalan, Sanjay, and Mark Cutkosky. "Error Analysis for the In-Situ Fabrication of Mechanisms." Journal of Mechanical Design 125, no. 4 (December 1, 2003): 809–22. http://dx.doi.org/10.1115/1.1631577.

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Fabrication techniques like Solid Freeform Fabrication (SFF), or Layered Manufacturing, enable the manufacture of completely pre-assembled mechanisms (i.e. those that require no explicit component assembly after fabrication). We refer to this manner of building assemblies as in-situ fabrication. An interesting issue that arises in this domain is the estimation of errors in the performance of such mechanisms as a consequence of manufacturing variability. Assumptions of parametric independence and stack-up made in conventional error analysis for mechanisms do not hold for this method of fabrication. In this paper we formulate a general technique for investigating the kinematic performance of mechanisms fabricated in-situ. The technique presented admits deterministic and stochastic error estimation of planar and spatial linkages with ideal joints. The method is illustrated with a planar example. Errors due to joint clearances, form errors, or other effects like link flexibility and driver-error, are not considered in the analysis—but are part of ongoing research.

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Jackson, T. R., W. Cho, N. M. Patrikalakis, and E. M. Sachs. "Memory Analysis of Solid Model Representations for Heterogeneous Objects." Journal of Computing and Information Science in Engineering 2, no. 1 (March 1, 2002): 1–10. http://dx.doi.org/10.1115/1.1476380.

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Methods to represent and exchange parts consisting of Functionally Graded Material (FGM) for Solid Freeform Fabrication (SFF) with Local Composition Control (LCC) are evaluated based on their memory requirements. Data structures for representing FGM objects as heterogeneous models are described and analyzed, including a voxel-based structure, finite-element mesh-based approach, and the extension of the Radial-Edge and Cell-Tuple-Graph data structures with Material Domains representing spatially varying composition properties. The storage cost for each data structure is derived in terms of the number of instances of each of its fundamental classes required to represent an FGM object. In order to determine the optimal data structure, the storage cost associated with each data structure is calculated for several hypothetical models. Limitations of these representation schemes are discussed and directions for future research also recommended.

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Su, W.-N., P. Erasenthiran, and P. M. Dickens. "Investigation of fully dense laser sintering of tool steel powder using a pulsed Nd: Yag (neodymium-doped yttrium aluminium garnet) laser." Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science 217, no. 1 (January 1, 2003): 127–38. http://dx.doi.org/10.1243/095440603762554677.

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A 550W neodymium-doped yttrium aluminium garnet (Nd:YAG) pulsed laser was used in the solid freeform fabrication (SFF) process to form fully dense sintered parts. Tool steel powder was chosen due to its wide acceptance in the tool-making industry. Unlike many processes applying either thermoplastic binder or metals of low melting points in the powder mixture, this process enables a direct fusion of material to solid parts without a further post-processing step. This paper presents a methodology and the results of high-power laser sintering of tool steel powder. The investigation includes the effects of various process parameters on the fully dense laser sintering results on a single bead and single layer and the related scan strategy to build up solid cubes. This process could eventually produce pre-forms with complex material structures rather than finished tools or parts.

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Au, Kin Man, and Kai Ming Yu. "Variable Radius Conformal Cooling Channel for Rapid Tool." Materials Science Forum 532-533 (December 2006): 520–23. http://dx.doi.org/10.4028/www.scientific.net/msf.532-533.520.

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The cooling system of a plastic injection mould is important as it affects the quality and productivity of the polymeric components or assemblies. Contemporary cooling channel design is confined to simple configurations of straight-drilled coolant passageway around the mould insert. Undesirable defects resulted during injection moulding, such as warpage, are inevitable. The application of rapid tool (RT) based on solid freeform fabrication (SFF) technologies with conformal cooling channel (CCC) design has provided a profound opportunity in quality improvement of polymeric components. In this study, a novel design of variable radius conformal cooling channel (VRCCC) is proposed to achieve better uniform cooling performance. Thermal-FEA and melt flow analysis are used to validate the method.

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Pandey, Pulak M. "On the Rapid Prototyping Technologies and Applications in Product Design and Manufacturing." Materials Science Forum 710 (January 2012): 101–9. http://dx.doi.org/10.4028/www.scientific.net/msf.710.101.

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Material removal, forming, casting and joining are the established manufacturing approaches and processes based on these approaches are being practiced even in modern industries with appropriate automation. Layer by layer material deposition method to produce prototypes from a solid model is relatively new and was developed during last 10-15 years of 20th century. These processes were named as Rapid Prototyping (RP) or Solid Freeform Fabrication (SFF). Today there are many commercial RP system and most of these able to deposit liquid or solid/powder polymer based materials. Some systems are also able to deposit blends of polymer and metal or ceramic. Latest trend in this area is to deposit metals or alloys with variable composition and hence to produce functionally graded material. This paper describes in general the details related to RP processes, data preparation, and various commercial RP technologies. The article also discusses applications these processes.

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Vasinonta, Aditad, Jack L. Beuth, and Michelle Griffith. "Process Maps for Predicting Residual Stress and Melt Pool Size in the Laser-Based Fabrication of Thin-Walled Structures." Journal of Manufacturing Science and Engineering 129, no. 1 (March 31, 2006): 101–9. http://dx.doi.org/10.1115/1.2335852.

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Thermomechanical models are presented for the building of thin-walled structures by laser-based solid freeform fabrication (SFF) processes. Thermal simulations are used to develop quasi-non-dimensional plots (termed process maps) that quantify the effects of changes in wall height, laser power, deposition speed, and part preheating on thermal gradients, with the goal of limiting residual stresses in manufactured components. Mechanical simulations are used to demonstrate the link between thermal gradients and maximum final residual stresses. The approach taken is analogous to that taken in previous research by the authors in developing process maps for melt pool length, for maintaining an optimal melt pool size during component fabrication. Process maps are tailored for application to the laser engineered net shaping process; however, the general approach, insights, and conclusions are applicable to most SFF processes involving a moving heat source, and to other laser-based fusion processes. Results from the residual stress simulations identify two mechanisms for reducing residual stresses and quantify maximum stress reductions achievable through manipulation of all process variables. Results from thermal gradient and melt pool length process maps are used to identify a manufacturing strategy for obtaining a consistent melt pool size while limiting residual stress in a thin-walled part.

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Binnard, Mike, and Mark R. Cutkosky. "Design by Composition for Layered Manufacturing*." Journal of Mechanical Design 122, no. 1 (January 1, 1999): 91–101. http://dx.doi.org/10.1115/1.533549.

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Three dimensional rapid prototyping processes, also called layered manufacturing or solid freeform fabrication (SFF), promise designers the ability to automatically fabricate complex shapes. SFF processes were invented with the assumption that designers would submit complete part models for automated planning and manufacturing. This planning process is normally based on some form of “decomposition,” for example, slicing into layers. Especially for newer, more complex SFF processes, there are several disadvantages to this approach, primarily that decomposition is difficult and does not reliably produce good process plans. Furthermore, it is hard for the designer to get feedback on the manufacturability of his design, and today’s decomposition systems are not fully automated. This paper presents an alternative approach, “design by composition,” where users build designs from “primitives” that include high-level manufacturing plans. When the user combines two primitives with a Boolean operation, software will automatically generate a manufacturing plan for the new design from the plans for the source primitives. In contrast to the decomposition method, design by composition offers several benefits to designers, primarily access to manufacturability feedback during design-time, a greater degree of automation, the ability to create designs with embedded components (such as sensors, electronic circuits, bearings, and shafts), and enhanced control over manufacturing plans. These advantages make design by composition a more attractive approach to SFF processing, especially for designers who are new to these processes. [S1050-0472(00)01701-3]

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Rodrı´guez, Jose´ F., James P. Thomas, and John E. Renaud. "Design of Fused-Deposition ABS Components for Stiffness and Strength." Journal of Mechanical Design 125, no. 3 (September 1, 2003): 545–51. http://dx.doi.org/10.1115/1.1582499.

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The high degree of automation of Solid Freeform Fabrication (SFF) processing and its ability to create geometrically complex parts to precise dimensions provide it with a unique potential for low volume production of rapid tooling and functional components. A factor of significant importance in the above applications is the capability of producing components with adequate mechanical performance (e.g., stiffness and strength). This paper introduces a strategy for optimizing the design of Fused-Deposition Acrylonitrile-Butadiene-Styrene (FD-ABS; P400) components for stiffness and strength under a given set of loading conditions. In this strategy, a mathematical model of the structural system is linked to an approximate minimization algorithm to find the settings of select manufacturing parameters, which optimize the mechanical performance of the component. The methodology is demonstrated by maximizing the load carrying capacity of a two-section cantilevered FD-ABS beam.

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Leong, K. F., K. K. S. Phua, C. K. Chua, Z. H. Du, and K. O. M. Teo. "Fabrication of porous polymeric matrix drug delivery devices using the selective laser sintering technique." Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine 215, no. 2 (February 1, 2001): 191–92. http://dx.doi.org/10.1243/0954411011533751.

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New techniques in solid freeform fabrication (SFF) have prompted research into methods of manufacturing and controlling porosity. The strategy of this research is to integrate computer aided design (CAD) and the SFF technique of selective laser sintering (SLS) to fabricate porous polymeric matrix drug delivery devices (DDDs). This study focuses on the control of the porosity of a matrix by manipulating the SLS process parameters of laser beam power and scan speed. Methylene blue dye is used as a drug model to infiltrate the matrices via a degassing method; visual inspection of dye penetration into the matrices is carried out. Most notably, the laser power matrices show a two-stage penetration process. The matrices are sectioned along the XZ planes and viewed under scanning electron microscope (SEM). The morphologies of the samples reveal a general increase in channel widths as laser power decreases and scan speed increases. The fractional release profiles of the matrices are determined by allowing the dye to diffuse out in vitro within a controlled environment. The results show that laser power and scan speed matrices deliver the dye for 8-9 days and have an evenly distributed profile. Mercury porosimetry is used to analyse the porosity of the matrices. Laser power matrices show a linear relationship between porosity and variation in parameter values. However, the same relationship for scan speed matrices turns out to be rather inconsistent. Relationships between the SLS parameters and the experimental results are developed using the fractional release rate equation for the infinite slab porous matrix DDD as a basis for correlation.

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Lee, Won Hee, Dong Soo Kim, Jung Su Kim, and Min Cheol Lee. "A Study on Reduction of Processing Time and Improvement of Strength by Using Photopolymer Resin in the 3DP Process." Key Engineering Materials 326-328 (December 2006): 151–54. http://dx.doi.org/10.4028/www.scientific.net/kem.326-328.151.

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3DP(three dimensional printing) technology is one of SFF(solid freeform fabrication) technologies which have recently come into a spotlight due to its adaptability to various applications. This technology has a great advantage in terms of short fabrication time for a prototype at a low cost, especially when it comes with multi-nozzle inkjet printing technology. However, it has also a disadvantage since it requires additional curing time, after jetting a binder material, and post-processing time in order to increase the mechanical strength of a product. In this study, a novel 3DP process is proposed to overcome slow solidification and elaborate post-process by adopting photo curing method into the conventional 3DP process. Mechanical properties, such as tensile and bending strengths, of specimens fabricated with the proposed 3DP process were measured and compared with those fabricated with the conventional 3DP process. As a result, it is found that mechanical strengths of specimens from the proposed novel 3DP process show three times higher than those from the conventional 3DP process. Besides, the overall fabrication time with the proposed novel 3DP process is about two times faster than that with the conventional 3DP process, because it does not need additional curing and post-processing time.

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Ahn, S. H., S. McMains, C. H. Séquin, and P. K. Wright. "Mechanical implementation services for rapid prototyping." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 216, no. 8 (August 1, 2002): 1193–99. http://dx.doi.org/10.1243/095440502760272467.

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Inspired by the metal oxide system implementation service (MOSIS) project, CyberCut is an experimental fabrication testbed for an Internet-accessible, computerized prototyping and machining service. Client-designers can create mechanical components, generally using our web-based computer aided design (CAD) system (available at http://cad.berkeley.edu ), and submit appropriate files to the server at Berkeley for process planning. CyberCut then utilizes an open-architecture, computer numerical control (CNC) machine tool for fabrication. Rapid tool path planning, novel fixturing techniques and sensor-based precision machining techniques allow the designer to take delivery of a component machined from high-strength materials with good tolerances, e.g. ±0.002in (0.05 mm). There are also instances where the complex geometry of a component cannot be prototyped on our three-axis machine tool. For these components use is made of solid freeform fabrication (SFF) technologies such as fused deposition modelling (FDM) to build a prototype of the design. Based on experience with this testbed, a new characterization of types of relationship, or ‘couplings’, between design and manufacturing has been developed using the three classifications ‘loose and repetitive’, ‘stiff and one-way’ or ‘strong and bidirectional’. These three couplings represent different trade-offs between ‘design flexibility’ and ‘guaranteed manufacturability’.

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Godlinski, Dirk, and Stéphane Morvan. "Steel Parts with Tailored Material Gradients by 3D-Printing Using Nano-Particulate Ink." Materials Science Forum 492-493 (August 2005): 679–84. http://dx.doi.org/10.4028/www.scientific.net/msf.492-493.679.

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It is difficult to generate any user-defined three dimensional gradient to tailor the functional properties of a component. Problems are not only the lack of local material design tools, but also a suitable manufacturing process. The implementation of the concept of local composition control into the Solid Freeform Fabrication (SFF) process 3D-Printing is described, which leads to geometrical complex parts out of tailored materials. Suspensions of different functional inks containing a binder and carbon black nano-particles are dispensed into droplets through multiple jets – like inkjet printing a halftone image on a paper – but into a metal powder bed to generate layer by layer graded green parts. In this case the tailored preforms are then sintered, while the nano-particle additions from the functional ink act locally as alloying elements in the steel matrix to combine e.g. both, toughness and hardness in the part. This work concentrates on the realisation of the new process and shows first results taking the generation of carbon-graded steel parts as an example.

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Hu, D., and R. Kovacevic. "Modelling and measuring the thermal behaviour of the molten pool in closed-loop controlled laser-based additive manufacturing." Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 217, no. 4 (April 1, 2003): 441–52. http://dx.doi.org/10.1243/095440503321628125.

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Laser-based additive manufacturing (LBAM) is a promising manufacturing technology that can be widely applied in solid freeform fabrication (SFF), component recovery and regeneration, and surface modification. The thermal behaviour of the molten pool is one of the critical factors that influences laser deposition indices such as geometrical accuracy, material properties and residual stresses. In this paper, a three-dimensional finite element model is developed using ANSYS to simulate the thermal behaviour of the molten pool in building a single-bead wall via a closed-loop controlled LBAM process in which the laser power is controlled to keep the width of the molten pool constant. The temperature distribution, the geometrical feature of the molten pool and the cooling rate under different process conditions are investigated. To verify the simulation results, the thermal behaviour of the molten pool is measured by a coaxially installed infrared camera in experimental investigations of a closed-loop controlled LBAM process. Results from finite element thermal analysis provide guidance for the process parameter selection in LBAM, and develop a base for further residual stress analysis.

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Amon, C. H., J. L. Beuth, L. E. Weiss, R. Merz, and F. B. Prinz. "Shape Deposition Manufacturing With Microcasting: Processing, Thermal and Mechanical Issues." Journal of Manufacturing Science and Engineering 120, no. 3 (August 1, 1998): 656–65. http://dx.doi.org/10.1115/1.2830171.

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Shape deposition manufacturing (SDM) is a solid freeform fabrication (SFF) methodology for automatically building up material layers to form three-dimensional, complex-shaped, multi-material structures. Microcasting is a molten metal droplet deposition process which is able to create fully dense metal layers with controlled microstructures. SDM combines microcasting with other intermediate processing operations, such as CNC machining and shot peening, to create high quality metal parts. In this paper, a description is given of SDM and the microcasting process. An overview of thermal and mechanical issues associated with SDM and microcasting is presented, including the control of interlayer metallurgical bonding through substrate remelting, the control of cooling rates of both the substrate and the deposited material and the minimization of residual thermal stress effects. Thermal models are used to study the issue of localized remelting of previously deposited material by newly deposited molten droplets to achieve metallurgical bonding. Mechanical modeling provides insight into residual stress build-up during part manufacture and residual stress-driven debonding between deposited layers.

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Liu, Fwu Hsing, Tsui Yen Ni, Yung Kang Shen, and Jeou Long Lee. "Rapid Forming of Hydroxyapatite-Silica Ceramics." Key Engineering Materials 450 (November 2010): 137–40. http://dx.doi.org/10.4028/www.scientific.net/kem.450.137.

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This paper proposes a solid freefrom fabrication (SFF) technology for fabricating hydroxyapatite(HA)-silica ceramics, which can generate porous three-dimensional physical objects. The HA powder and the silica are mixed with water into slurries form as raw materials. The slurries are paved by a scraper to from a thin layer which is selective scanned by a laser beam according to the cross-section of a 3D model. The HA particles are embeded in the sintered silica matrix to form green parts via a suitable range of process parameters. The benefits of this process are: bio-ceramic parts can be built by lower laser energy and faster fabricating speed. Following a subsequence heat treatment process has been developed to optimize the crystallization process and to increase the strength of the sintered parts. The parts were analyzed by an Atomic Force Microscope (AFM) to determine the surface roughness. The results obtained indicate that the proposed process was possible to generate multilayer, overhanging, and porous structure with brittle property but sufficient integrity for handling prior to post-processing. It was possible to produce the porous structure from the proposed hydroxyapatite-silica ceramics, which had a greater potential for possible bone scaffolds fabrication.

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Kumar, Mohit, and Varun Sharma. "Additive manufacturing techniques for the fabrication of tissue engineering scaffolds: a review." Rapid Prototyping Journal 27, no. 6 (July 5, 2021): 1230–72. http://dx.doi.org/10.1108/rpj-01-2021-0011.

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Purpose Additive manufacturing (AM) or solid freeform fabrication (SFF) technique is extensively used to produce intrinsic 3D structures with high accuracy. Its significant contributions in the field of tissue engineering (TE) have significantly increased in the recent years. TE is used to regenerate or repair impaired tissues which are caused by trauma, disease and injury in human body. There are a number of novel materials such as polymers, ceramics and composites, which possess immense potential for production of scaffolds. However, the major challenge is in developing those bioactive and patient-specific scaffolds, which have a required controlled design like pore architecture with good interconnectivity, optimized porosity and microstructure. Such design not only supports cell proliferation but also promotes good adhesion and differentiation. However, the traditional techniques fail to fulfill all the required specific properties in tissue scaffold. The purpose of this study is to report the review on AM techniques for the fabrication of TE scaffolds. Design/methodology/approach The present review paper provides a detailed analysis of the widely used AM techniques to construct tissue scaffolds using stereolithography (SLA), selective laser sintering (SLS), fused deposition modeling (FDM), binder jetting (BJ) and advanced or hybrid additive manufacturing methods. Findings Subsequently, this study also focuses on understanding the concepts of TE scaffolds and their characteristics, working principle of scaffolds fabrication process. Besides this, mechanical properties, characteristics of microstructure, in vitro and in vivo analysis of the fabricated scaffolds have also been discussed in detail. Originality/value The review paper highlights the way forward in the area of additive manufacturing applications in TE field by following a systematic review methodology.

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Ahn, SeungHyun, Young Ho Koh, and GeunHyung Kim. "A three-dimensional hierarchical collagen scaffold fabricated by a combined solid freeform fabrication (SFF) and electrospinning process to enhance mesenchymal stem cell (MSC) proliferation." Journal of Micromechanics and Microengineering 20, no. 6 (May 14, 2010): 065015. http://dx.doi.org/10.1088/0960-1317/20/6/065015.

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Boudreau, Douglas B., Liza-Anastasia DiCecco, Olufisayo A. Gali, and Afsaneh Edrisy. "Fatigue Behaviour of Additive Manufactured Ti-TiB." MRS Advances 3, no. 62 (2018): 3641–53. http://dx.doi.org/10.1557/adv.2018.618.

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ABSTRACTFatigue behaviour of titanium reinforced with TiB particles fabricated by ‘plasma transferred arc solid freeform fabrication’ (PTA-SFFF) technique was investigated. Rotation bending fatigue tests were conducted following the MPIF 56 standard using the staircase method approach. Experimental data is used to calculate the fatigue strength and construct S-N curves, where the results were compared to a powder metallurgy FC0205 as a benchmark material. The titanium samples were found to exhibit superior fatigue behaviour in comparison to the reference FC0205 material, performing well above 1/3 of its ultimate tensile strength with a 90% survival fatigue strength of 244 +/- 98.3 MPa versus 141 +/- 17.4 MPa. Fatigue failure mechanisms of samples were identified by examination of the fracture surfaces through scanning electron microscopy (SEM) as well as using transmission-electron microscopy (TEM) and focused ion beam (FIB) analysis techniques. Fatigue crack propagation was either arrested or deflected when propagation occurred within the vicinity of the TiB intermetallics. Fracture surfaces of the titanium matrix displayed evidence of striations while the TiB intermetallic experience cleavage fracture.

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Bourell, David L. "Solid Freeform Fabrication." JOM 71, no. 3 (October 30, 2018): 869–70. http://dx.doi.org/10.1007/s11837-018-3206-4.

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36

Crawford, R. H., and J. J. Beaman. "Solid freeform fabrication." IEEE Spectrum 36, no. 2 (February 1999): 34–43. http://dx.doi.org/10.1109/6.744874.

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Bourell, David L. "Solid Freeform Fabrication." JOM 70, no. 3 (January 4, 2018): 370–71. http://dx.doi.org/10.1007/s11837-017-2715-x.

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38

Cawley, James D. "Solid freeform fabrication of ceramics." Current Opinion in Solid State and Materials Science 4, no. 5 (October 1999): 483–89. http://dx.doi.org/10.1016/s1359-0286(99)00055-8.

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Tay, B. Y., J. R. G. Evans, and M. J. Edirisinghe. "Solid freeform fabrication of ceramics." International Materials Reviews 48, no. 6 (December 2003): 341–70. http://dx.doi.org/10.1179/095066003225010263.

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C.L. Wang, Charlie, and Yong Chen. "Thickening freeform surfaces for solid fabrication." Rapid Prototyping Journal 19, no. 6 (September 30, 2013): 395–406. http://dx.doi.org/10.1108/rpj-02-2012-0013.

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41

Manthiram, A., D. L. Bourell, and H. L. Marcus. "Nanophase materials in solid freeform fabrication." JOM 45, no. 11 (November 1993): 66–70. http://dx.doi.org/10.1007/bf03222493.

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Rice, Christopher S., Patricio F. Mendez, and Stuart B. Brown. "Metal solid freeform fabrication using semi-solid slurries." JOM 52, no. 12 (December 2000): 31–33. http://dx.doi.org/10.1007/s11837-000-0065-5.

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Costa, Lino, Deepak Rajput, Kathleen Lansford, Wenqiang Yue, Alexander Terekhov, and William Hofmeister. "The tower nozzle solid freeform fabrication technique." Rapid Prototyping Journal 16, no. 4 (June 15, 2010): 295–301. http://dx.doi.org/10.1108/13552541011049315.

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NIINO, Toshiki, and Yasuyuki SAKAI. "Solid Freeform Fabrication of Tissue Engineering Scaffolds." Journal of the Japan Society for Precision Engineering 73, no. 5 (2007): 528–32. http://dx.doi.org/10.2493/jjspe.73.528.

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Chappell, W. J., C. Reilly, J. Halloran, and L. P. B. Katehi. "Ceramic synthetic substrates using solid freeform fabrication." IEEE Transactions on Microwave Theory and Techniques 51, no. 3 (March 2003): 752–60. http://dx.doi.org/10.1109/tmtt.2003.808727.

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Kwak, Sung-Jo, and Doo-Yong Lee. "Process Optimization of Industrial Solid Freeform Fabrication System." Transactions of the Korean Society of Mechanical Engineers A 32, no. 7 (July 1, 2008): 602–9. http://dx.doi.org/10.3795/ksme-a.2008.32.7.602.

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Bourell, D. "Solid freeform fabrication of powders using laser processing." Metal Powder Report 52, no. 7-8 (July 1997): 43. http://dx.doi.org/10.1016/s0026-0657(97)80238-x.

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Bourell, D. "Solid freeform fabrication of powders using laser processing." Metal Powder Report 53, no. 7-8 (July 8, 1997): 43. http://dx.doi.org/10.1016/s0026-0657(97)84744-3.

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Calvert, Paul, John O'Kelly, and Chad Souvignier. "Solid freeform fabrication of organic-inorganic hybrid materials." Materials Science and Engineering: C 6, no. 2-3 (November 1998): 167–74. http://dx.doi.org/10.1016/s0928-4931(98)00046-0.

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Godbold, O. B., R. C. Soar, and R. A. Buswell. "Implications of solid freeform fabrication on acoustic absorbers." Rapid Prototyping Journal 13, no. 5 (October 2, 2007): 298–303. http://dx.doi.org/10.1108/13552540710824805.

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Journal articles on the topic 'Solid Freeform Fabrication (SFF)'

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