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Metal additive manufacturing using lasers
Published in Rupinder Singh, J. Paulo Davim, Additive Manufacturing, 2018
C. P. Paul, A. N. Jinoop, K. S. Bindra
The system is integrated with a 5-axis workstation for job manipulation. The five axes are X, Y, Z, V and W. The X, Y and Z axes are linear traverse axes mutually perpendicular to each other, whereas V is a tilt axis about the Y-axis, for tilting the laser head, and W is a continuous rotational axis about the X-axis. The effective stroke length of the linear axis is 250 mm. The angular tilt of the V axis is ±110°, whereas the W axis is capable of a 360° continuous rotation. The manipulator is interfaced with a standard computer numerical controller for manipulating the workstation. The laser head coupled with a manipulator is mounted in a glove box. The glove box is essentially required for maintaining controlled atmospheric conditions during processing. Oxygen and moisture are the main impurities in the atmosphere, which affects the properties of the deposited bulk materials. Therefore, the system is integrated with oxygen and moisture analysers. The desired purity levels are achieved by purging high purity grade Argon gas. In case there is an increase in the impurity level, the high purging rate is used to reinstate the indented purity level in the glove box. The purity level of the glove box is retained by keeping the differential pressure just above the atmospheric pressure. Figure 2.16 shows the LAM process at RRCAT.
Verification of plant and equipment seismic design on the Sellafield Mixed Oxide Fuel Plant
Published in Edmund Booth, Seismic Design Practice into the Next Century, 1998
To prevent any loss of radioactive materials, particularly plutonium, to the environment, much of the manufacturing process for the SMP is carried out in interconnected gloveboxes. Gloveboxes are essentially sealed metal containers with special windows to allow operators to observe maintenance operations and gloveports for operators to perform maintenance. Normal operation of the equipment is by remotely monitored means with no operators physically located by the gloveboxes. The gloveboxes range in size depending on the operations performed in them – larger gloveboxes are about 2m by 4m in plan and 5m tall.
Systems Based on GaSb
Published in Tomashyk Vasyl, Ternary Alloys Based on III-V Semiconductors, 2017
Yb11GaSb9 also crystallizes in the orthorhombic structure with the lattice parameters a = 1173.20 ± 0.13, b = 1231.99 ± 0.13, and c = 1664.01 ± 0.18 pm (Yi et al. 2010) (a = 1172.57 ± 0.12, b = 1232.04 ± 0.13, and c = 1663.3 ± 0.2 pm and a calculated density of 8.483 g⋅cm–3 at 90 ± 3 K [Bobev et al. 2005]). To obtain the title compound, the starting materials were loaded in an alumina crucible with a stoichiometric ratio of Yb/Ga/Sb at 11:76:9 (Yi et al. 2010). The crucible was put in a fused silica ampoule with quartz wool on the top and at the bottom, which was then sealed under a vacuum. The reaction was heated in a furnace under the following temperature profile: heating to 500°C from room temperature in 2 h and dwelling at 500°C for 6 h, and then ramping to 1000°C within 2 h and dwelling for 6 h at this temperature, followed by cooling to 600°C at a rate of 2°C⋅h–1. At this point, the ampoule was quickly removed from the furnace, inverted, and centrifuged to remove the extra flux. It could also be synthesized by direct fusion of the corresponding elements, and large single crystals were prepared from high-temperature flux synthesis (Bobev et al. 2005). All materials were handled in a nitrogen-filled glove box or with other inert atmosphere techniques.
Additive manufacturing of metallic biomaterials: sustainability aspect, opportunity, and challenges
Published in Journal of Industrial and Production Engineering, 2023
Pralhad Pesode, Shivprakash Barve
The whole product development cycle, which takes into account both financial and esthetic considerations and includes product designing studios, supply networks, processing & assembly lines, is only then ready to be rearranged by an industry [25]. Patients may find it challenging to quickly find a prosthesis or splint that matches their anatomical endowments in such a mass-oriented rehabilitation market. Here, AM saves the day by creating patient-specific, customized utility on-site, removing all manufacturing and distribution barriers, and providing a long-term solution [21]. The process becomes more flexible and sustainable by eliminating the need for large warehouses to store inventory, reducing the length of lengthy supply chains for material processing, eliminating labor-intensive assembly lines, and replacing them with single-piece product creation while allowing for on-demand spot fabrication as required. However, there are some issues with AM processes such as storage for metal powder. In order to prevent mishaps like fire, it is usually preferable for this to be a temporary or restricted storage for the powder being used at the time rather than the main store for this activity. It is advised that the storage be anti-static, fireproof, and sealed against moisture and humidity. Powders are typically delivered in containers with varied capacities that may weigh more than 10 kg, making it challenging to put the powder directly into the build chamber. The metal powder is typically transferred into smaller containers using a glovebox. Additionally, this process enhances the powder deposition on the machined bed and the conditions of the powder from being stacked during export and storage. Some gloveboxes can be fed with a continuous gas stream and are made to operate in inert gas environments to prevent oxidation and inflammation. To prevent asphyxia in the event of an inert gas leak, oxygen gas sensors are necessary for sensing the quantity of oxygen in the lab. Typically, these sensors are mounted at a height of around 80 cm above the ground. The metal printer must have a safe and constant supply of inert gas throughout the process. When removing the parts and cleaning the powder, vacuum cleaners are crucial. For the best trapping of powder particles and isolation from air exposure, most powder metal types typically employ a wet cleaner (filled with water). To manage the range of powder particle sizes, sieving systems in various mesh sizes are required. They are also essential for removing any spattered particles, trash, and scrap metals from the old powders for recycling and reusing. Especially in the case of unsuccessful prints, these spattered particles and debris may be created during the melting process and transmitted to the overflow container. These are some limitations of additive manufacturing as opposed to traditional manufacturing [26].