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ing line also eased refractory coating application to the final surface. Vertical and horizontal parting lines were designed to split the runner in half to allow complete removal of all uncured sand from the runner and gates, reduc- ing the possibility for uncured sand to be in the mold. Vertical parting lines introduce the possibility of metal runout dur- ing pouring. Tis risk can be reduced by two ways: having sufficient sand volume below the runner to quickly reduce any runout to solidus tempera- ture and/or having sufficient mold overlap with drafting for a near-per- fect mating surface. Te interlocking surface traps any runout in place and the large volume of sand around the stationary runout quickly freezes the metal. Te yellow path in Figure 6 is the short distance of travel at 6.8 in. Bonded sand is the most expen-


sive consumable required for 3-D printing. 3-D printing facilities often charge based upon the mold volume


INDUSTRY EFFORTS TO PROMOTE 3-D PRINTING


Based in Youngstown, Ohio, America Makes is the nation’s leading collabora- tive partner in additive manufacaturing and 3-D printing technology research, discovery, creation and innovation. The American Foundry Society is partnering with Youngstown Business Incubator (YBI), which has been named a recipient of funds from America Makes. America Makes is focused on helping the U.S. grow its capabilities and strength in 3-D printing, also known as additive manufacturing, by facilitating collaboration among leaders from business, academia, non-profit organizations and government agencies. Focusing on areas that include design, materials, technology, workforce and more, America Makes aims to make the U.S.’s 3-D printing industry become more globally competitive.


Visit americamakes.us for more information.


of the bonded sand. Te flexibility of being able to design and print the 3-D model allows design engineers to efficiently use sand. Figure 7 shows the original mold before removing sand from non-critical areas. It weighed 124.68 lbs. (56.67 kg). Figure 8 shows the reduced mold after having sand removal techniques applied with a weight of 113.16 lbs. (51.43 kg), a


weight reduction of 10.18%. Mold weight reduction allows for easier assembly and reduces the shipping cost of molds and cores.


Orientation of Parts Part orientation to the printing head


ensures the part’s final dimensional accuracy, especially in smaller cores with tight tolerances. When the Z layer is


May 2015 MODERN CASTING | 27


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