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sand printing is lower than conventional mold making. As the final three core geometries were approached, the 3-D sand printed cores were consoli- dated into a single core pro- viding a cost advantage over conventional moldmaking. Figure 10 presents the


combined effects of tooling and fabrication costs and part design complexity factor. For a production volume of less than 26 castings, 3-D sand printing is more affordable than conventional pattern- making even in the case of casting without any cores. However, for produc-


Fig 8. Tooling costs as a function of complexity is shown for Case Study 2.


tion volume greater than 26 castings, it depends on the level of part-core complexity. As seen in Case Study 1, the breakeven point shifts to increas- ing levels of complexity as the quantity increases. In the case of 1,000 castings, as observed in Case Study 1, the tool- ing cost per mold/set is significantly lower since fabrication costs is more significant and the scenario is very similar to Figure 9.


Future Work


In order to accelerate the adoption of emerging technology such as 3-D sand


printing in the metalcasting industry, this study recommends future work to examine the combinations of conven- tional patternmaking and 3-D sand printing for a single casting. For example, the economics of using conventional patterns for molds and 3-D sand print- ing for complex cores could be explored. Further, economics and fabrication time associated with using alternative additive manufacturing technologies for pattern- making such as material extrusion (also known as fused deposition modeling) could be explored.


Tis study assumed the 3-D sand


molds and cores printing provided an equivalent surface finish and sand performance with tradi- tional pattern making for mold and core manufac- turing. However, an exten- sion to this study would focus on incorporating additional factors to incor- porate such attributes. Tus, evaluation of such factors can be achieved by measuring surface finish and testing of physical and mechanical properties. Tis work will give additional evaluation criteria for both approaches along with estimated cost.


Finally, incorporating these results


into a CAD–CAM software system would be immediately beneficial. Te end user should be able to plug in the geometric attributes of the castings as shown in Table 1 and input cost parameters such as materials, consum- ables, labor, depreciation and other costs for both patternmaking and 3-D sand printing.


Tis article is a summary of a manuscript published in the International Journal of Metalcasting. For more information on the manuscript, contact the AFS technical department at 800-537-4237.


Fig 9. The fabrication costs for Case Study 2 for 3-D sand printing costs and conventional patternmaking are shown.


Fig 10. This chart depicts the total costs (tooling and fabrication) for Case Study 2 where conventional patternmaking costs are shown for quantities of 26, 100 and 1,000 units.


34 | MODERN CASTING April 2017


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