Metal additive manufacturing marks a new shift in the manufacturing industry similar to the invention of casting techniques. Metal 3D printing has developed to where functional 3D metal printed parts are used in complex machinery. Metal additive manufacturing can reduce lead time, material cost, and weight for complex metal geometry parts that are near or even impossible with subtractive techniques.

Simple geometry such as creating brackets or blocking should not be replaced with additive manufacturing as the time to 3D print is not efficient or financially justifiable. Additive manufacturing techniques are currently being used in applications where undercutting, integrated porous or cooling ducts, and part consolidation is needed. The strength to weight ratio of metal 3D printed parts can be manipulated as well to fulfill necessary requirements in high-performance dynamic machinery such as aerospace crafts. The ducting and porosity of the part shown in figure 1 from ASME, shows a complexity example designed for additive manufacturing that is impossible with conventional techniques.

Figure 1: ASME Additive Manufactured Part

Conventional manufacturing techniques such as die-casting are capable of creating internal features in some instances but the tooling costs and cavity inserts will create high overhead cost. Not to mention the part design is final once the tooling has been created. Parts that may need to be modified or produced in low quantities may be a good fit for an additive process in order to avoid expensive tooling costs. Shown in the graph below, metal 3D printed parts are justifiable to the left of the curve intersection.

Figure 2: Quantity to Cost Ratio

Companies that are incorporating additive manufacturing into production utilize the free-forming capabilities of internal geometry but that doesn’t mean this process comes without a range of challenges. The challenges of high-speed and large-scale production for metal 3D printing are not as repeatable or accurate compared to conventional casting techniques. The surface finish of additive manufacturing is not smooth or consistent unless additional post-surface finishing is used, this will further increase the cost of metal 3D printing. 

The concerns with additive manufacturing are continuously being improved with each coming year as the technology grows and advances. Current technology supports additive manufacturing for low volume and/or have complexity that has impossible geometry as subtractive tooling cannot access part features.

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