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

The Use of Layered Freeform Fabrication Technologies to Produce Tissue Engineering Scaffolds for Skull Patches

Congenital skull defects in infants are difficult to correct using metal plates due to the growth of the skull. Tissue engineering of bone patches could be the answer to help such patients. Custom scaffolds have been designed based on Computed Tomography (CT) images of the patient’s skull. An in-house developed single screw extruder, casting and a commercial laser cutter has been evaluated in the fabrication of pure polycaprolactone (PCL) scaffolds as well as PCL mixed with hydroxyapatite (HA) scaffolds. Evaluation criteria for each process included the ability to maintain an optimal pore size for cells to proliferate, inclusion of micro surface properties for cell adhesion, incorporation of hydroxyapatite, and ability to maintain desired shape. The mechanical properties of the fabricated scaffolds will be presented in this paper as well as initial cell seeding results with human adipose-derived adult stem (hADAS) cells.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

Advanced Manufacturing Using Linked Processes: Hybrid Manufacturing

Hybrid Manufacturing Processes (HMP) can significantly reduce time to customer, waste, and tooling costs per part, while increasing possible part geometric complexity for small batch parts. In the following chapter, HMP is defined by the production of parts produced first with a near-net shape process using methods including: additive manufacturing, casting, injection molding, etc., which is then coupled with multi-axis computer numerical control (CNC) subtractive machining or some other secondary material removal process. Creating process plans for such hybrid manufacturing processes typically takes weeks rather than hours or days. This chapter outlines several hybrid manufacturing processes and the intricacies required to develop process plans for these complex linked processes. A feature-based advanced hybrid manufacturing process planning system (FAH-PS) uses feature-specific geometric, tolerance, and material data inputs to generate automated process plans based on user-specified feature precedence for additive-subtractive hybrid manufacturing. Plans generated by FAH-PS can optimize process plans to minimize tool changes, orientation changes, etc., to improve process times. A case study of additive-subtractive methods for a patient-specific bone plate, demonstrates system capabilities and processing time reductions as compared to the current manual process planning for hybrid manufacturing methodologies. Using the generated FAH-PS process plan resulted in a 35% reduction in machining time from the current hybrid manufacturing strategy

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

Freeform Fabrication of Titanium Aluminide via Electron Beam Melting Using Prealloyed and Blended Powders

Titanium aluminide (TiAl) is an intermetallic compound possessing excellent high-temperature performance while having significantly lower density than nickel-based superalloys. This paper presents preliminary results of experiments aimed at processing TiAl via the electron beam melting (EBM) process. Two processing routes are explored. The first uses prealloyed powder, whereas the second explores controlled reaction synthesis. Issues such as processing parameters, vaporization of alloying elements, microstructure, and properties are discussed