Characterization of Thin Walled Ti-6Al-4V Components Reduced via Electron Beam Melting

Direct-metal energy beam SFF processes typically produce layers by scanning the contours and then filling in the area within the contour. Process parameters used to solidify contours are often different from those for fill areas. It is to be expected, therefore, that the contour and fill area regions will have different microstructures. This can have important ramifications for thin walled components such as biomedical implants whose slices have very little fill area. This paper characterizes the metallurgical differences in contour and fill areas in titanium components produced via Electron Beam Melting. The implications of these properties for thin walled components are described.Mechanical Engineerin

Performances of novel custom 3D-printed cutting guide in canine caudal maxillectomy: a cadaveric study

IntroductionCaudal maxillectomies are challenging procedures for most veterinary surgeons. Custom guides may allow the procedure to become more accessible.MethodsA cadaveric study was performed to evaluate the accuracy and efficiency of stereolithography guided (3D-printed) caudal maxillectomy. Mean absolute linear deviation from planned to performed cuts and mean procedure duration were compared pairwise between three study groups, with 10 canine cadaver head sides per group: 3D-printed guided caudal maxillectomy performed by an experienced surgeon (ESG) and a novice surgery resident (NSG), and freehand procedure performed by an experienced surgeon (ESF).ResultsAccuracy was systematically higher for ESG versus ESF, and statistically significant for 4 of 5 osteotomies (p < 0.05). There was no statistical difference in accuracy between ESG and NSG. The highest absolute mean linear deviation for ESG was <2 mm and >5 mm for ESF. Procedure duration was statistically significantly longer for ESG than ESF (p < 0.001), and for NSG than ESG (p < 0.001).DiscussionSurgical accuracy of canine caudal maxillectomy was improved with the use of our novel custom cutting guide, despite a longer duration procedure. Improved accuracy obtained with the use of the custom cutting guide could prove beneficial in achieving complete oncologic margins. The time increase might be acceptable if hemorrhage can be adequately controlled in vivo. Further development in custom guides may improve the overall efficacy of the procedure

Characterization of High Alloy Steel Produced Via Electron Beam Melting

Electron Beam Melting (EBM) is a direct-to-metal freeform fabrication technique in which a 4 kW electron beam is used to melt metal powder in a layer-wise fashion. As this process is relatively new, there have not yet been any independently published studies of the high alloy steel microstructural properties. This paper describes the EBM process and presents results of microstructural analyses on H13 tool steel processed via EBM.Mechanical Engineerin

Rapid Manufacturing with Electron Beam Melting (EBM) - A Manufacturing Revolution?

The Electron Beam Melting technology is the result of intensive research and development and has a wide array of applications within areas such as Rapid Prototyping, Rapid Manufacturing, Tooling and Biomedical Engineering. The technology combines first-class material properties with high build speeds. The presentation will provide a basic understanding of the technology, technical status, applications and ongoing R&D.Mechanical Engineerin

Powder removal from Ti-6Al-4V cellular structures fabricated via electron beam melting

Direct metal fabrication systems like electron beam melting (EBM) and direct metal laser sintering (also called selective laser melting) are gaining popularity. One reason is the design and fabrication freedom that these technologies offer over traditional processes. One specific feature that is of interest is mesh or lattice structures that can be produced using these powder-bed systems. One issue with the EBM process is that the powder trapped within the structure during the fabrication process is sintered and can be hard to remove as the mesh density increases. This is usually not an issue for the laser-based systems since most of them work at a low temperature and the sintering of the powder is less of an issue. Within the scope of this project, a chemical etching process was evaluated for sintered powder removal using three different cellular structures with varying mesh densities. All meshes were fabricated via EBM using Ti6Al4V Footnote Information powder. The results are promising, but the larger the structures, the more difficult it is to completely remove the sintered powder without affecting the integrity of the mesh structure

Shear Properties of the Re-Entrant Auxetic Structure Made via Electron Beam Melting

While the tensile/compressive mechanical properties of the re-entrant auxetic cellular structure have been relatively well modeled, their shear properties including the shear modulus and shear strength have not been investigated. This paper focuses on the analytical modeling of the shear properties of this auxetic structure utilizing beam analysis. The modeling results were further compared with results from both simulation and experimentation. It was found that in addition to the effective length reduction effect, the size effect also becomes significant for the shearing of this re-entrant auxetic structures. Due to the size effect, it was expected that the re-entrant auxetic structure could not be effectively homogenized based on the developed analytical property model, and additional design factors must be considered in the future.Mechanical Engineerin

Direct Fabrication of Metal Orthopedic Implants Using Electron Beam Melting Technology

Metal orthopedic implants have been used for many decades with great success. Replacement joints and plates for bone fractures are usually made from titanium, cobaltchromium or stainless steel. Through recent advancements in biomodeling, custom orthopedic implants can be designed. However, fabrication of these custom implants can be prohibitively expensive with traditional processes. With the introduction of Electron Beam Melting (EBM), direct fabrication of fully dense metal components is possible. In this paper, the development of titanium for the EBM-process will be discussed, and direct fabrication of custom designed orthopedic implants made out of steel and titanium will be demonstrated.Mechanical Engineerin

Custom-designed orthopedic implants evaluated using finite element analysis of patient-specific computed tomography data: femoral-component case study

<p>Abstract</p> <p>Background</p> <p>Conventional knee and hip implant systems have been in use for many years with good success. However, the custom design of implant components based on patient-specific anatomy has been attempted to overcome existing shortcomings of current designs. The longevity of cementless implant components is highly dependent on the initial fit between the bone surface and the implant. The bone-implant interface design has historically been limited by the surgical tools and cutting guides available; and the cost of fabricating custom-designed implant components has been prohibitive.</p> <p>Methods</p> <p>This paper describes an approach where the custom design is based on a Computed Tomography scan of the patient's joint. The proposed design will customize both the articulating surface and the bone-implant interface to address the most common problems found with conventional knee-implant components. Finite Element Analysis is used to evaluate and compare the proposed design of a custom femoral component with a conventional design.</p> <p>Results</p> <p>The proposed design shows a more even stress distribution on the bone-implant interface surface, which will reduce the uneven bone remodeling that can lead to premature loosening.</p> <p>Conclusion</p> <p>The proposed custom femoral component design has the following advantages compared with a conventional femoral component. (i) Since the articulating surface closely mimics the shape of the distal femur, there is no need for resurfacing of the patella or gait change. (ii) Owing to the resulting stress distribution, bone remodeling is even and the risk of premature loosening might be reduced. (iii) Because the bone-implant interface can accommodate anatomical abnormalities at the distal femur, the need for surgical interventions and fitting of filler components is reduced. (iv) Given that the bone-implant interface is customized, about 40% less bone must be removed. The primary disadvantages are the time and cost required for the design and the possible need for a surgical robot to perform the bone resection. Some of these disadvantages may be eliminated by the use of rapid prototyping technologies, especially the use of Electron Beam Melting technology for quick and economical fabrication of custom implant components.</p