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shown in Figure 2 include two main components: pattern and coreboxes. Tooling cost is influenced by pattern material, part size, desired accuracy and part complexity. Hence, it can be concluded that tooling cost for complex part geometry with larger part size and greater accuracy will be significantly higher than traditional manufacturing of tooling (for similar mold-core material).


Te tooling cost in metalcasting Fig 1. Shown is a process map of conventional sand casting. Among several cost factors in sand


casting, two major cost components are the tooling and fabrication costs which involve a variety of operations to produce the mold and cores and subsequent inspection. Te unit cost of a corebox depends on the number of cores, cavity geometry/size, mold and core sizes and production volume for that specific part design (i.e., number of castings per design). In the case of traditional mold making, additional operations are required with multiple cores including the assembly of the cores, bonding of cores and inspection. Several studies have identified the


relationship between complex part designs which require multiple cores and its impact on tooling cost in traditional approaches to fabricate a corebox. In conventional manufactur- ing of sand molds, the production cost is influenced directly by part complex- ity because of the need for multiple


operations, special tools, skilled labor, significant tool wear and lower productivity. Another analysis showed it was evident the cost for machin- ing tooling was relatively higher for complex part designs with similar geometric volume. Components of tooling costs


facilities and pattern shops usually is amortized over the number of cast- ings produced and is a critical factor that increases unit cost during low production volume. Tooling cost is a fixed initial cost in traditional mold making and this negatively impacts the number of part designs that can be produced economically. Tis is espe- cially true for low quantity produc- tion that would occur during product development. Te motivation of this study was to develop a model based on part design complexity, production volume and tooling-fabrication costs of coreboxes. Te developed model can be applied to evaluate the economic feasibility of traditional sand casting methods and 3-D sand printing for varied combinations of part designs and production volume.


The Complexity Factor Te methodology employed in this


Fig 2. Components of tooling cost include materials, size, complexity and accuracy.


study involves: • The creation of CAD models for each casting design for evaluation.


Fig 3. The side (a) and angular views of the casting (transparent) and cores (gray) are shown. April 2017 MODERN CASTING | 31


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