Rapid Prototyping Machine Research Articles

Rapid Prototyping STL Reconstruction for CT Medical Image in Fused Deposition Modelling

The main objective of this research is to reconstruct 3D rapid prototyping (RP) models for computer tomography (CT) medical images in fused deposition modeling (FDM). It demonstrates a technique to convert medical images to points cloud, and simplify into STL (Stereo-Lithography) triangular meshes for RP machine in fused deposition modelling. The grey prediction algorithm is used to sort contour point data in each layer of the medical image. The contour difference detection operation is used to sequence the points for each layer. The 3D STL meshes are then constructed by layer-by-layer sequence meshes algorithm to build the STL file. Once this STL file is saved, a 3D physical model of the medical image can be fabricated by FDM RP manufacturing, and its virtual reality model can also be presented for visualization. CT images of a human skull and femur bone were used as the case studies for the construction of the 3D solid model with medical images. The STL models generated using this new methodology compared to commercial computer-aided design (CAD) models. The results of this research are therefore clinically reliable in reconstructing 3D STL models for CT medical images.

Creation of cell models from confocal microscopy data files using rapid prototyping

A novel process was developed to convert digital data files from confocal microscopy of cells into three‐dimensional models. This process produces accurate models of cells as compared to existing methods that primarily rely on renditions. Data sets form Confocal Laser Scanning Microscopy (CLSM) and Multiphoton Laser Scanning Microscopy (MPLSM) for C. elegans embryo were converted to TIFF files using open source program Image J. Following importing files in Mimics, a medical imaging program, a slice distance of 4uM was chosen for modeling. Following enhancement, a Boolean operation was performed creating 2 separate segmentation masks, one for cellular structures and the other for exterior wall of embryo. The files were then exported into Freeform Modeling program which allowed us to convert 3‐D computer images into virtual clay. Files were further converted to a .stl format which can be read by rapid prototyping machine spectrum ZTM 510 (Z Corporation) 3D printer. Another build using 3D systems 250 SLA employing the DSM Somos Watershed XC 11122 resin was accomplished. The novel process described for building accurate 3‐D models of cells could find use in producing specimens for educational, research and clinical applications. Supported by National Science Foundation, grant EEC‐0648845 awarded to Subha Kumpaty, Department of Mechanical Engineering, Milwaukee School of Engineering.

Physical models of enzymes engineered for biofuel cells: 2010 Pingry School S.M.A.R.T. Team Project

The 2010 Pingry School S.M.A.R.T. Team (Students Modeling A Research Topic) has been working with the Banta laboratory at Columbia University to design and produce accurate, three‐dimensional physical models of alcohol dehydrogenase AdhD and other enzymes with applications for use in a biofuel cell. Features being engineered into these enzymes include (1) self‐assembly into hydrogels, (2) alternate cofactor use, and (3) broader substrate specificity. Discussions with the Banta laboratory allowed the students to use RP‐RasMol to design models of enzymes studied in the lab to highlight their structural and functional characteristics. These designs were used to direct rapid prototyping machines to build physical models of these enzymes. Along with Jmol tutorials created on the Team website (www.pingrysmartteam.com) and in Proteopedia (www.proteopedia.org), these physical models serve as “communication tools” used to enhance the understanding of these enzymes and their applications among the scientific and academic community. By contributing this new tool to the Banta laboratory research team, the students have the unique opportunity to experience and participate in the activities of a research laboratory. This work is supported by a grant awarded to Tim Herman by the NIH NCRR SEPA program and the HHMI Precollege Science Education Program.

Product-form design model based on genetic algorithms

Industrial design attempts to enhance quality of life by designing products that meet consumer requirements. Combining concepts from various fields, including design, computer technology, aesthetics, and economics, industrial designers seek to improve quality of life by designing products that meet consumer needs. Industrial designers focus on customers' perceptions of products and their preferences for certain shapes, textures, colors, styles, linguistic variables, prices, and functions. Because new products are continuously being released, manufacturers must continually design products to satisfy customer needs to avoid displacement by market competitors. When planning strategies for marketing products to various users and consumers, managers must often consider multiple combinations of product shapes and must design products that cater to consumer tastes to minimize the risk of their products being rejected by the market. Companies with highly-skilled designers have more ideas, better and more competitive products, and shorter production times than companies with weak designers. This study analyzed product styles by applying genetic algorithms and Kansei Engineering Type II (AHP and Quantification Theory Type I). This research transforms the psychological conceptions of consumers into linguistic variables. A MATLAB program was constructed to enable designers to simulate consumer logic. The cognitive dissonance between virtual and real models was minimized by using a 3D CAD model, and the virtual model of optimum solutions in this study employed a rapid prototyping machine to generate real models efficiently. Future genetic algorithm models applying different decision theories may achieve even faster and more accurate results. Relevance to industry Component diversification enables rapid improvement in product competitiveness. This study proposes a support model that conforms to the psychological preferences of consumers by applying a genetic algorithm method. Therefore, the model is applicable to electronic commerce websites or to other unmanned shops.

The Development of a Rapid Prototyping Prosthetic Socket Coated with a Resin Layer for Transtibial Amputees

This article proposes a type of transtibial socket composed of an inner layer fabricated by a rapid prototyping (RP) machine and an outer layer coated with unsaturated polyester resin. This work integrates contemporary technologies including a handheld scanner and CAD systems, to design a thin primary socket shape and then manufactures the socket using a fused deposition-modeling machine. To prevent breakage caused by the layer-based forming process and to reinforce flexural strength, the current research coats the preliminary RP socket with a layer of unsaturated polyester resin. After shaping the proximal brim of the resin-reinforced RP socket to match the specific stump, this study assembles and aligns a shank and a prosthetic foot to form a prosthesis set. After completing a trial safety walk wearing the prosthesis, which is satisfactory to the amputee and a registered prosthetist, this research measures interface pressures between the stump and the resin-reinforced RP socket. Experiment results demonstrate that the resin-reinforced RP socket is applicable for transtibial amputees. In addition to strengthening the FDM socket and producing consistent socket fit, this study also demonstrates a feasible procedure that employs current technologies to design and manufacture transtibial sockets without plaster moulds.

Identification of Precious Artefacts: The Sonic Imprint for Small Artefacts

Identification of artworks is mainly based on a few characteristics which can be observed using non-invasive tools (sight, touch, simple instruments), the investigated properties being geometry, weight, colours, texture, etc. Nowadays, technology allows reproducing all these characteristics to such an extent that even expert conservators can be deceived: in particular at the present time even the geometry of an artwork can be easily reproduced with the help of laser scanner analysis and with a rapid prototyping machine or a computer numerical control (CNC) milling machine. We propose a new tool, the Sonic Imprint, producing a code capable of identifying a rigid artefact from its vibrational resonance frequencies beyond doubt. In fact the vibration modes of an artefact strongly depend on the spatial distributions of its density and elastic parameters, as well as on its internal defects, definable in terms of abrupt changes of elastic properties in a small portion of the object. Then even small differences of these properties (differences usually present even among “identical” objects produced with industrial methods, at least in terms of defects) give appreciable variations of the Sonic Imprint codes, allowing secure identification of artworks, prevention of clonation and even damage monitoring. Moreover the procedure is really robust, rapid, inexpensive and not invasive. We tested it on a large number of commercial objects with the same shape and dimension and on many artworks in archaeological museums: an example is described. The application of this methodology to small-size artefacts (from small stones, vessels, pottery to medium-large coins) involves some problems in the detection of the Sonic Imprint. The problems, just due to the smaller sizes of this kind of objects, arise from the presence of higher resonance frequencies and larger damping of the induced vibrations. This implies that probes and instrumentation should be replaced to be adapted to the new experimental conditions.

Systematic user-based assessment of “Navigated Control Spine” / Systematische, nutzerzentrierte Evaluation von „Navigated Control Spine”

The aim of this study was the systematic preclinical assessment of a new mill for spinal surgery. This mill automatically switches off at predefined workspace margins. The system is called the "Navigated Control Spine". The workspace is planned intraoperatively with fluoroscopic images. Assessment was performed in a simulated surgical scenario with real surgical instruments and equipment, and the following criteria were measured: "milling accuracy" and "surgical workflow parameters". To simulate the patient, an anatomical spine model was created with a Rapid Prototyping machine. The models included electronic components that simulate injuries to the structures at risk. For the workflow parameters, the results show differences between experienced and inexperienced surgeons. The maximum accuracy for experienced surgeons was +0.31 mm and for inexperienced surgeons +0.57 mm. The dura, as one of the structures at risk, was never injured.

An Aesthetics Driven Approach to Jewelry Design

AbstractThis paper proposes a computer-based design tool to automate art form generation used in jewelry design. Expert system and evolutionary algorithm are integrated into the prototype design tool named JAFG (Jewelry Art Form Generator). Art forms are represented using iterated function system (IFS) fractals. Case-based reasoning method and fuzzy logic are used for calculating case similarity to increase the efficiency of existing art forms retrieval. An evolutionary algorithm is used as a mechanism to generate new art forms. A rule-based reasoning with a forward chaining IF-THEN rule method is applied to estimate production cost. An automated model-making module integrated into the design system provides users with an option to manufacture jewelry prototypes using a computer numerical control (CNC) or a rapid prototyping (RP) machine. Examples are given to illustrate how JAFG operates.

An experimental design approach to manufacture of parts using fused deposition modelling

Investigating the mechanical properties of the parts manufactured from rapid prototyping (RP) machine is important for rapid manufacturing. It is necessary that, the identification of effect of different combination of process parameters to get the desired mechanical properties. This paper presents a method to manufacture parts with different combination of process parameters of fused deposition modelling (FDM) using design of experiments. The effect of road width (RW) and raster angle (RA) on density, hardness, and surface roughness is investigated. The experiments have been conducted based on second order central composite rotatable design which is one type of response surface methodology. The 13 samples are prepared and tested. From the results, the regression coefficients are calculated and fitted to the general form of quadratic equation for two factors. By using statistical analysis, the significance of the various factors is determined. The final relation shows the effect of input parameters over the output response.

Manufacturing parts optimization in the three‐dimensional printing process by the Taguchi method

The functional requirements of three‐dimensional printing systems are speed, accuracy and the strength of the green‐part. However, these functional indices are significantly affected by the properties of the adopted materials and the manufacturing process parameters of the rapid prototyping machine. The four most important process parameters were systematically investigated in this study. Using the ANOVA analysis techniques of the Taguchi method and adjusting the shrinkage setup values, we determined the optimal parameter setup values for NCKU‐1 powder and reduced the dimensional accuracy error to ±0.08 mm, ±0.07 mm and ±0.06 mm in the X‐, Y‐and Z‐direction, respectively. The results also show that these optimized parameters can shorten building time by 9.57% and increase flexural stress by 31.27%. Finally, the quality properties were also examined separately for ZP 100 and NCKU‐1 powder. It is concluded that building time decreased by 16.5%, binder consumption was reduced by 35.4% and flexural stress increased 172.88% if the powder was changed from ZP 100 to NCKU‐1.

Heuristics for Direct Slicing of Point Clouds for Layered Manufacturing

Reverse Engineering and Rapid Prototyping are integrated mostly using the tessellated STL (Solid-to-Layer) file. If copies of 3D scanned products are needed in a few time, the polygonization task is normally performed on the point cloud, often generating errors, requiring high computational effort, and heavy human intervention. In this paper it is proposed to overcome the limitations of polygonization by using direct slicing of point clouds, modelling the problem as a travelling salesman problem (TSP), solved basing on the heuristic technique called cheapest insertion. The point cloud is decomposed into elementary voxels, then, considering each Z level of the voxelized point cloud, the external non-void voxels are linked together, using the above mentioned heuristics, to generate the contour of the object with an automatic process. The contour of the object can be easily converted into commercial slice files suitable for Rapid Prototyping machines. The approach is applied to several complex shaped models to prove its robustness and efficiency.

Fabrication of patient specific fasciaform molds for formaldehyde fasciaform grafting tympanoplasty

In this paper, we report a procedure for making a patient specific Fasciaform Mold for a Formaldehyde Fasciaform Grafting Tympanoplasty procedure based on Computer Tomography (CT) of the patient's temporal bone. Three dimensional ear canal models were first reconstructed from the CT scans of patients. The models were then used by CNC (Computer Numeric Control) machines for making stainless steel molds as well as rapid prototyping machines for producing acrylic based polymer molds. Both a stainless steel mold and a pair of plastic acrylic molds were produced for Formaldehyde Fasciaform Grafting Tympanoplasty. The procedure is found to be feasible in producing a patient specific fasciaform mold within a reasonable time.

Non-uniform deformation of an STL model satisfying error criteria

In this research, a method is presented for generating a deformed model satisfying given error criteria from an STL model in a triangular-mesh representation suitable for rapid prototyping (RP) processes. A deformed model is a non-uniformly modified shape from a base STL model. In developing a family product with various sizes such as a shoe, sometimes prototypes for all sizes should be made using an RP machine. Although an STL model is generated from a solid model, it is well known that creating a non-uniformly modified solid model from a base solid model is very difficult. Generally there are some gaps between surfaces after modification, and stitching the gaps is very difficult. To solve this problem, the authors explored the possibility of generating a deformed STL model directly from a base STL model. This research includes a data structure for modifying the STL model, checking the error of a modified edge compared with the exact non-uniformly scaled curve, checking the error of a modified facet compared with the exact non-uniformly scaled surface, and splitting a facet with an error greater than the allowable tolerance. Using the results of this research, the difficult work of creating solid models to build non-uniformly deformed STL models could be avoided.

A partial mesh replacement technique for design modification in rapid prototyping

Most rapid prototyping machines accept the .STL format as the universal format of the geometric model, where the substance of the .STL format is essentially a triangular model. A partial replacement of the meshes in such a model is practically necessary, but has been received little attention. The purpose of this study is to develop a partial mesh replacement technique for replacing a region of meshes along a closed region of profile. The proposed method is primarily composed of three steps: cutting path computation, mesh segmentation and mesh stitching. The cutting path computation is employed to evaluate the intersecting points of all meshes lying under the projection of the boundary curve. Mesh segmentation is employed to divide the original meshes into two parts: preserved and replaced meshes. Mesh stitching is finally employed to sew the boundaries of the preserved and new meshes. Several examples are presented to demonstrate the feasibility and application of the proposed method.

Rapid Manufacturing of Metal-Ceramic Composites

This paper presents a layer manufacturing technology called selective laser gelling (SLG) to fabricate metal-ceramic composites green parts which are difficult to construct using traditional methods for fabricating composites. When a layer of metal-ceramic slurry is scanned via Nd: YAG laser radiation, the metal particles are gelled together by the silica sol to form a composites part. In comparison with other composites processes, the features of this process include lower laser forming energy, faster fabrication speed, less dimensional variations. The material composition is mixing by the stainless steel powder and a silica sol in a proportion of 75 to 25 wt. %. A series of experiments was conducted to obtain the smallest pave-able layer thickness of 50 μm on an experimental rapid prototyping (RP) machine. The feasibility of this process was demonstrated by manufacturing a gear shaped prototype with a surface finish of 18μm under a laser energy density of 3.5 J/mm2.

Rapid fabrication of custom patient biopsy guides

Image‐guided surgery is currently performed using frame‐based as well as frameless approaches. In order to reduce the invasive nature of stereotactic guidance and the cost in both equipment and time required within the operating room, we investigated the use of rapid prototyping (RP) technology. In our approach, we fabricated custom patient‐specific face masks and guides that can be applied to the patient during stereotactic surgery. While the use of RP machines has previously been shown to be satisfactory from an accuracy standpoint, one of our design criteria – completing the entire build and introduction into the sterile field in less than two hours – was unobtainable. (1) Our primary problems were the fabrication time and the nonresistance of the built material to high‐temperature sterilization. In the current study, we have investigated the use of subtractive rapid prototyping (SRP) machines to perform the same quality of surgical guidance, while improving the fabrication time and allowing for choosing materials suitable for sterilization. Because SRP technology does not offer the same flexibility as RP in terms of prototype shape and complexity, our software program was adapted to provide new guide designs suitable for SRP fabrication. The biopsy guide was subdivided for a more efficient build with the parts being uniquely assembled to form the final guide. The accuracy of the assembly was then assessed using a modified Brown‐Roberts‐Wells phantom base by which the position of a biopsy needle introduced into the guide can be measured and compared with the actual planned target. These tests showed that: 1) SRP machines provide an average technical accuracy of 0.77 mm with a standard deviation of the mean of 0.07 mm, and 2) SRP allows for fabrication and sterilization within three‐and‐a‐half hours after diagnostic image acquisition. We are confident that technology is capable of reducing this time to less than one hour. Further tests are being conducted to determine the registration accuracy of the face mask on the patient's head under IRB‐approved trials. The accuracy of this new guidance technology will be verified by judging it against current frame‐based or frameless systems.PACS number: 87.57.Gg

3-Dimensional Printing of Models to Create Custom-Made Devices for Coil Embolization of an Anastomotic Leak After Aortic Arch Replacement

The objective of this study was to show the use of 3-dimensional printing models to fabricate a custom-made occluder for device embolization of an anastomotic leak after replacement of the ascending aorta and the aortic arch in a human immunodeficiency virus (HIV)-infected patient. We present a 50-year-old HIV-infected patient who underwent ascending aorta and aortic arch replacement for a type A dissection, and who had an aortic arch pseudoaneurysm (sized 5 x 5 x 4 cm) with a slit-shaped entrance hole located anteriorly to the implanted supra-aortic vessels. The patient's 128-slice computed tomography data were visualized and reconstructed. Afterward we fabricated a life-like replica of the complex pathology of the ascending aorta and the aortic arch using a rapid prototyping machine. After careful examination of the model, we fabricated a custom-made occluder device for interventional closure of the leakage. Using data derived from 128-slid computed tomography linked to proprietary software, we were able to create models of the ascending aorta, the aortic arch end, especially the pseudoaneurysm with its slit-shaped opening between the aortic lumen and the aneurysm. This was very helpful to build a perfectly fitting custom-made occluder device to plan and simulate the interventional closure. Moreover, the models were helpful for intra-interventional orientation. The stereolithographic replicas were extremely useful for choosing the treatment option and for planning and simulating the occlusion of the pseudoaneurysm. Furthermore, the models were necessary for our engineers who were building the custom-made occluder device.

Fabrication of Customized Bio-Electrode for Neural Stimulation Using Rapid Prototyping Technique

In the treatment of disorders, bio-electrodes are used to be implanted into the patients’ deep brain for long-term stimulation. This paper presents a custom design and flexible fabrication process of bio-electrode for treating neural disorders using rapid prototyping (RP) technique. A 3D model of the bio-electrode is designed and the photosensitive resin electrode prototype is fabricated on the laser rapid prototyping machine, and then the bio-electrode is fabricated using this electrode prototype and the silicon rubber mold and winding technique. The spatial distribution of the electric field fabricated of the bio-electrode is analyzed, and the optical photomicrograph reveals that the cylindrical surfaces of the polyurethane of the bio-electrode have smooth surface and no visible microcracks, and the spiral lines are arranged densely and have no defects of loose and falling and partly protruding. The electrochemical experiments show that the electrochemical process of the bio-electrode is reversible and the bio-electrode has good functionality and stability property.

Correction of hemifacial microsomia with the help of mirror imaging and a rapid prototyping technique: case report

A 23-year-old man presented with an 8-year history of unilateral hemifacial microsomia. A three-dimensional model of the maxillofacial bones was generated after acquisition of helical computed tomographic data. A customised implant model was designed by projecting a mirror image of the healthy mandible on to the three-dimensional model. A resin model of the implant was then made using a rapid prototyping machine. A polymeric biomaterial was sculpted according to the model and implanted into the affected side of the mandible to restore his facial symmetry. The hemifacial microsomia was corrected and a symmetrical facial contour obtained. No complications developed during the 6-year follow-up.

Fabrication of an Auricular Prosthesis Using Computed Tomography and Rapid Prototyping Technique

This article describes the use of computed tomography and rapid prototyping method to produce a wax pattern of a missing ear. Computed tomographic scans were obtained from the patient, and a three-dimensional digital image was produced using a computer-aided design software. Then, the image of the present ear was extracted, and its mirror image was obtained with the software. The pattern of the inverted three-dimensional cast was produced using a rapid prototyping machine. The cast was duplicated in wax of identical dimensions and shape of the opposing ear, and the auricular prosthesis was fabricated with traditional methods.