Rapid Tooling via Stereolithography

Approximately three years ago, composite stereolithography (SL) resins were introduced to the marketplace, offering performance features beyond what traditional SL resins could offer. In particular, the high heat deflection temperatures and high stiffness of these highly filled resins have opened the door to several new rapid prototyping (RP) applications, including wind tunnel test modelling and, more recently, rapid tooling.

Rapid Tooling mit Stereolithographie

Vor etwa drei Jahren wurden Komposit-Kunstharze für die Stereolithographie (SL) auf dem Markt eingeführt. Sie bieten Leistungsmerkmale, die jenseits dessen liegen, was traditionelle SL-Kunstharze auszeichnet. Insbesondere die hohe Wärmeformbeständigkeit und hohe Steifigkeit dieser Komposit-Kunstharze haben verschiedenen neuen Rapid-Prototyping(RP)-Anwendungen den Weg bereitet.

Rapid Manufacturing - eine interdisziplinäre Strategie

Als um 1987 ein Verfahren namens Stereolithographie und ein Stereolithography Apparatus (SLA) vorgestellt wurden, war der Traum von der Herstellung beliebiger dreidimensionaler Bauteile direkt aus Computerdaten und ohne bauteilspezifische Werkzeuge Realität geworden.

Rapid Manufacturing in der Kleinserienproduktion

Die enormen Fortschritte der Rechentechnik in den vergangenen 60 Jahren ermöglichten vielfältige Berechnungen, Simulationen und nicht zu letzt 3D-Konstruktionen sowie deren einheitliches Beschreiben mittels 3D-Flächendaten. Ebenso wurde es möglich real existierende Gegenstände zu vermessen und als 3D-Geometrie datentechnisch zu hinterlegen.

Möglichkeiten des Rapid Manufacturing im Sondermaschinenbau

Durch eine praxisnahe Beratung von Konstrukteuren und Einkäufern auch in kleineren Firmen, konnten gewinnbringende Einsatzmöglichkeiten im Sondermaschinenbau realisiert werden. Die Rapid Manufacturing Anwendungen die sehr erfolgreich im Luftführungsbereich eingesetzt sind, weisen deutliche Vorteile für den Kunden auf.

Trends and Expertise Exchange within Rapid Manufacturing in Europe

Rapid Manufacturing (RM) umfasst den Begriff der direkten und wirtschaftlichen Bauteilherstellung des Serienprodukts aus 3D-Daten. Die Hauptvorteile sind u.a. das Wegfallen von Werkzeugen und eine Designfreiheit in der Produktentwicklung, die noch vor wenigen Jahren undenkbar war. Wenngleich heute eine Vielzahl von Werkstoffen im Kunststoff- und Metallbereich einsetzbar sind, konzentriert sich die Verbreitung des RM allerdings auf besondere Technologie- und Wirtschaftszweige, aufgrund mangelnder Erfahrungswerte, teilweise abweichender Werkstoffeigenschaften, fehlender Standards und ungeeigneter Testmethoden. In der Praxis sind Ingenieure und Techniker stark darauf bedacht, auf etablierte Abläufe und Standards zurückzugreifen. Es ist daher schwer einen geeigneten RM-Prozess aufzubauen, wo wichtige Eingangsgrößen meist unbekannt sind. In diesem Bericht wird beschrieben, welche Informationskanäle es innerhalb Europas zum Thema RM gibt und welche Hochschulen und Forschungszentren Aktivitäten aufweisen. Darüber hinaus werden Anwendungsfelder des RM aufgeführt, die über die bekannten Anwendungsfelder hinaus gehen. Dazu gehören Anwendungen im Bereich der Elektrotechnik, Raumfahrtinstrumentation und der Mode. Obwohl nicht alle Anwendungen des RM in diesem Bericht aufgeführt werden, sind einige Schlüsselinformationen im Bereich innovativer Anwendungen von RM enthalten.

Advantages and pitfalls in computer assisted orthopedic surgery planning using rapid-prototyped guides

Durch die von Rapid Prototyping gebotenen Möglichkeiten können computergestützte 3D Operationsplanungen präzise in der Operation umgesetzt werden. An der Universitätsklinik Balgrist wurden in den letzten 3 Jahren nahezu 100 Patienten erfolgreich behandelt, deren Operation in 3D geplant und mit patienten-spezifischen Schablonen umgesetzt wurde. Wir beschreiben die Genauigkeit dieser Methode und berichten über die hierbei gesammelten Erfahrungen. Aufgrund der Flexibilität der Rapid Prototyping Technologie, gibt es nicht immer nur einen Weg wie eine 3D geplante Operation umgesetzt werden kann. Wir zeigen daher anhand von Fallbeispielen unterschiedliche Strategien auf und beschreiben deren Vor- und Nachteile. Ausserdem präsentieren wir die Weiterentwicklung der Methode zur Anwendung an kleinerer Anatomie wie Knochen des Handgelenkes oder der Finger.

Rapid manufacturing of aluminum components

A manufacturing technique for the production of aluminum components is described. A resin-bonded part is formed by a rapid prototyping technique and then debound and infiltrated by a second aluminum alloy under a nitrogen atmosphere. During thermal processing, the aluminum reacts with the nitrogen and is partially transformed into a rigid aluminum nitride skeleton, which provides the structural rigidity during infiltration. The simplicity and rapidity of this process in comparison to conventional production routes, combined with the ability to fabricate complicated parts of almost any geometry and with high dimensional precision, provide an additional means to manufacture aluminum components.

Development and mechanical testing of a short intramedullary nail for fixation of femoral rotational osteotomy in cerebral palsy patients

Background: Rotational osteotomy is frequently indicated to correct excessive femoral anteversion in cerebral palsy patients. Angled blade plate is the standard fixation device used when performed in the proximal femur, but extensile exposure is required for plate accommodation. The authors developed a short locked intramedullary nail to be applied percutaneously in the fixation of femoral rotational osteotomies in children with cerebral palsy and evaluated its mechanical properties. Methods: The study was divided into three stages. In the first part, a prototype was designed and made based on radiographic measurements of the femoral medullary canal of ten-year-old patients. In the second, synthetic femoral models based on rapid-prototyping of 3D reconstructed images of patients with cerebral palsy were obtained and were employed to adjust the nail prototype to the morphological changes observed in this disease. In the third, rotational osteotomies were simulated using synthetic femoral models stabilized by the nail and by the AO-ASIF fixed-angle blade plate. Mechanical testing was done comparing both devices in bending-compression and torsion. Results: The authors observed proper adaptation of the nail to normal and morphologically altered femoral models, and during the simulated osteotomies. Stiffness in bending-compression was significantly higher in the group fixed by the plate (388.97 +/- 57.25 N/mm) than in that fixed by the nail (268.26 +/- 38.51 N/mm) as torsional relative stiffness was significantly higher in the group fixed by the plate (1.07 +/- 0.36 Nm/degrees) than by the nail (0.35 +/- 0.13 Nm/degrees). Conclusions: Although the device presented adequate design and dimension to fit into the pediatric femur, mechanical tests indicated that the nail was less stable than the blade plate in bending-compression and torsion. This may be a beneficial property, and it can be attributed to the more flexible fixation found in intramedullary devices.

Biomodel-guided stereotaxy

OBJECTIVES: To simplify the practice of stereotactic surgery by using an original method, apparatus, and solid anatomic replica for trajectory planning and to validate the method and apparatus in a laboratory and clinical trial. METHODS: The patient is marked with fiducials and scanned by using computed tomography or magnetic resonance imaging. The three-dimensional data are converted to a format acceptable to stereolithography. Stereolithography uses a laser to polymerize photosensitive resin into a solid plastic model (biomodel). Stereolithography can replicate brood vessels, soft tissue, tumor, and bone accurately (

The new craft skills of engineering: The impact of innovation technology on engineering practices

This chapter explores the impact of innovation technologies such as simulation, modelling, and rapid prototyping on engineering practice. Innovation technologies help redefine the role of engineers in the innovation process, creating a new division of innovative labour both with and across organizations. This chapter also explores the boundaries of experimentation and inertia within particular domains of problem-solving to create new opportunities and value.

Tooth Tissue Engineering: Optimal Dental Stem Cell Harvest Based on Tooth Development

Our long-term objective is to devise reliable methods to generate biological replacement teeth exhibiting the physical properties and functions of naturally formed human teeth. Previously, we demonstrated the successful use of tissue engineering approaches to generate small, bioengineered tooth crowns from harvested pig and rat postnatal dental stem cells (DSCs). To facilitate characterizations of human DSCs, we have developed a novel radiographic staging system to accurately correlate human third molar tooth developmental stage with anticipated harvested DSC yield. Our results demonstrated that DSC yields were higher in less developed teeth (Stages 1 and 2), and lower in more developed teeth (Stages 3, 4, and 5). The greatest cell yields and colony-forming units (CFUs) capability was obtained from Stages 1 and 2 tooth dental pulp. We conclude that radiographic developmental staging can be used to accurately assess the utility of harvested human teeth for future dental tissue engineering applications.

Precise Insertion of Orthodontic Miniscrews with a Stereolithographic Surgical Guide Based on Cone Beam Computed Tomography Data: A Pilot Study

Purpose: Orthodontic miniscrews are commonly used to achieve absolute anchorage during tooth movement. One of the most frequent complications is screw loss as a result of root contact. Increased precision during the process of miniscrew insertion would help prevent screw loss and potential root damage, improving treatment outcomes. Stereo lithographic surgical guides have been commonly used for prosthetic implants to increase the precision of insertion. The objective of this paper was to describe the use of a stereolithographic surgical guide suitable for one-component orthodontic miniscrews based on cone beam computed tomography (CBCT) data and to evaluate implant placement accuracy. Materials and Methods: Acrylic splints were adapted to the dental arches of four patients, and six radiopaque reference points were filled with gutta-percha. The patients were submitted to CBCT while they wore the occlusal splint. Another series of images was captured with the splint alone. After superimposition and segmentation, miniscrew insertion was simulated using planning software that allowed the user to check the implant position in all planes and in three dimensions. In a rapid-prototyping machine, a stereolithographic guide was fabricated with metallic sleeves located at the insertion points to allow for three-dimensional control of the pilot bur. The surgical guide was worn during surgery. After implant insertion, each patient was submitted to CBCT a second time to verify the implant position and the accuracy of the placement of the miniscrews. Results: The average differences between the planned and inserted positions for the ten miniscrews were 0.86 mm at the coronal end, 0.71 mm at the center, and 0.87 mm at the apical tip. The average angular discrepancy was 1.76 degrees. Conclusions: The use of stereolithographic surgical guides based on CBCT data allows for accurate orthodontic mini screw insertion without damaging neighboring anatomic structures. INT J ORAL MAXILLOFAC IMPLANTS 2011;26:860-865

Monolithic CAD/CAM Lithium Disilicate Versus Veneered Y-TZP Crowns: Comparison of Failure Modes and Reliability After Fatigue

Purpose: The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate and hand-layer-veneered zirconia all-ceramic crowns. Materials and Methods: A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic lithium disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different step-stress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated. Results: Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic lithium disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM lithium disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the lithium disilicate ceramic in the range of 1,100 to 1,200 N. Conclusion: Based on present fatigue findings, the application of CAD/CAM lithium disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures. Int J Prosthodont 2010; 23: 434-442.

Surgical planning for resection of an ameloblastoma and reconstruction of the mandible using a selective laser sintering 3D biomodel

Ameloblastoma is a benign locally aggressive infiltrative odontogenic lesion. It is characterized by slow growth and painless swelling. The treatment for ameloblastoma varies from curettage to en bloc resection, and the reported recurrence rates after treatment are high; the safety margin of resection is important to avoid recurrence. Advances in technology brought about great benefits in dentistry; a new generation of computed tomography scanners and 3-dimensional images enhance the surgical planning and management of maxillofacial tumors. The development of new prototyping systems provides accurate 3D biomodels on which surgery can be simulated, especially in cases of ameloblastoma, in which the safety margin is important for treatment success. A case of mandibular follicular ameloblastoma is reported where a 3D biomodel was used before and during surgery.