OCTOBER 20239MANUFACTURING TECHNOLOGY INSIGHTSbetter surface finishes and the ability to create finer features, produce parts with higher densities, and print net shape parts. Depending on the print manufacturer, LPBF does require a setup and break-down time of more than an hour. This technology could trap powder in hollow spaces or internal fluid paths, which increases the time in post-processing steps to remove the unsintered powder. Design considerations are very important so that powder does not get trapped and becomes a safety, performance, or FOD risk.Directed energy deposition (DED) uses a laser or electron beam to sinter powder or wire feedstock dispensed from a nozzle on a 4 or 5-axis arm. Therefore, parts are built up with the swift use of minor additional material, but there is a loss intolerance and a rougher surface finish. DED also requires more support material and post-processing finishing/machining than LPBF. This technology shines in repairs where a damaged part is put in the machine to add material wherever necessary. DED machines can use multiple materials in the same build, whereas LPBF is limited to one material per print. DED machines also tend to have a larger build volume than LPBF machines.Like LPBF, a binder jet dispenses powder in thin layers but also uses a liquid binder to hold the part together rather than sintering it with a laser. The part is post-processed by sintering and washing the binder out of it. This method is great for automotive and aerospace, as it tends to produce a part quicker than LPBF. However, the post-processing required can take longer time, especially if parts are thicker, as it will take longer for the debinder to reach its center. Parts can also have trouble printing net-shape parts and will not have as high of a density as parts produced using LPBF directly out of the printer. If batched together, this technology has a much lower cost on entry into metal additive manufacturing and can produce parts at a lower price than those of DED and LPBF.Like any manufacturing method, AM has advantages and drawbacks that one must be mindful of when deciding if a part should be produced additively. While there are various methods discussed above that are quite different, most information covered below will pertain to all/most metal AM techniques. Its major advantage is the ability to rapidly create prototypes and shorten the lead times of production parts. It is also important to note that the lead time for printing the part may be shorter than machining or vacuum brazing, but projects with long, complex post-process operations will most likely see lesser benefits than those with minimal post-processing operations. Additive manufacturing has also opened the door to designing geometry that would otherwise be impossible to create at minimal to no added cost for the increasing complexity. For example, in LPBF, a 1" cube costs roughly the same as a 1" block of lattice structure or triply periodic minimal surface. This is a major advantage for AM, drawing interest in a wide array of industries, including the manufacturing of heat exchangers. It is also possible to hold tight tolerances and produce very small features with additive manufacturing, making it great for printing net shape or near net shape parts that require minimal machining. Another great upside to additive manufacturing, especially laser powder bed fusion and DED, is the ability to recycle and reuse non-sintered powder from previous jobs. There are ways to properly maintain lot control of your powders and reclaim most of the unused powder after each print.Additive manufacturing is a great addition for many companies to add to their manufacturing repertoire; however, it's important to know and understand its limitations. Metal AM is still relatively new, so there is a limited selection of materials and data available for purchase. It is also challenging to track and maintain good material lot control, especially when there are a lot of printers and different materials in one location. The powdered metal material used in laser powder bed fusion, binder jet, and some types of DED also tends to have health and safety risks that are not present with wrought or cast metal feedstock. If not handled properly, aluminum powder can be dangerous and is considered a chemical of interest for the Department of Homeland Security (DHS). The buying and storing of aluminum powders on-site requires regular audits by DHS. It is important to remember that, like any other manufacturing technique, additive manufacturing needs to make sense for your application. As the industry grows and specifications and guidelines are established, it is important to educate customers on the benefits of additive manufacturing and work with those customers early in the design process to determine if it fits the product and choose the best metal additive technology to fit the tolerances, part size, and budget. Additive manufacturing is a great addition for many companies to add to their manufacturing repertoire; however, it's important to know and understand its limitations
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