“CoreCavity: interactive shell decomposition for fabrication with two-piece rigid molds” by Nakashima, Auzinger, Iarussi, Zhang, Igarashi, et al. …

  • ©Kazutaka Nakashima, Thomas Auzinger, Emmanuel Iarussi, Ran Zhang, Takeo Igarashi, and Bernd Bickel



Entry Number: 135

Session Title:

    New Additions (and Subtractions) to Fabrication


    CoreCavity: interactive shell decomposition for fabrication with two-piece rigid molds




    Molding is a popular mass production method, in which the initial expenses for the mold are offset by the low per-unit production cost. However, the physical fabrication constraints of the molding technique commonly restrict the shape of moldable objects. For a complex shape, a decomposition of the object into moldable parts is a common strategy to address these constraints, with plastic model kits being a popular and illustrative example. However, conducting such a decomposition requires considerable expertise, and it depends on the technical aspects of the fabrication technique, as well as aesthetic considerations. We present an interactive technique to create such decompositions for two-piece molding, in which each part of the object is cast between two rigid mold pieces. Given the surface description of an object, we decompose its thin-shell equivalent into moldable parts by first performing a coarse decomposition and then utilizing an active contour model for the boundaries between individual parts. Formulated as an optimization problem, the movement of the contours is guided by an energy reflecting fabrication constraints to ensure the moldability of each part. Simultaneously the user is provided with editing capabilities to enforce aesthetic guidelines. Our interactive interface provides control of the contour positions by allowing, for example, the alignment of part boundaries with object features. Our technique enables a novel workflow, as it empowers novice users to explore the design space, and it generates fabrication-ready two-piece molds that can be used either for casting or industrial injection molding of free-form objects.


    1. Giuseppe Alemanno, Paolo Cignoni, Nico Pietroni, Federico Ponchio, and Roberto Scopigno. 2014. Interlocking Pieces for Printing Tangible Cultural Heritage Replicas. (2014).Google Scholar
    2. Stephan Bischoff, Tobias Weyand, and Leif Kobbelt. 2005. Snakes on Triangle Meshes. In Bildverarbeitung fÃÿr die Medizin 2005. Springer-Verlag, 208–212.Google ScholarCross Ref
    3. J. C. Carr, R. K. Beatson, J. B. Cherrie, T. J. Mitchell, W. R. Fright, B. C. McCallum, and T. R. Evans. 2001. Reconstruction and representation of 3D objects with radial basis functions. In Proceedings of the 28th annual conference on Computer graphics and interactive techniques – SIGGRAPH ’01. ACM Press Google ScholarDigital Library
    4. Pritam Chakraborty and N. Venkata Reddy. 2009. Automatic determination of parting directions, parting lines and surfaces for two-piece permanent molds. Journal of Materials Processing Technology 209, 5 (mar 2009), 2464–2476.Google ScholarCross Ref
    5. Xuelin Chen, Hao Zhang, Jinjie Lin, Ruizhen Hu, Lin Lu, Qixing Huang, Bedrich Benes, Daniel Cohen-Or, and Baoquan Chen. 2015. Dapper: decompose-and-pack for 3D printing. ACM Transactions on Graphics 34, 6 (oct 2015), 1–12. Google ScholarDigital Library
    6. David Cohen-Steiner, Pierre Alliez, and Mathieu Desbrun. 2004. Variational shape approximation. ACM Transactions on Graphics 23, 3 (aug 2004), 905. Google ScholarDigital Library
    7. Sándor P. Fekete and Joseph S. B. Mitchell. 2001. Terrain Decomposition and Layered Manufacturing. International Journal of Computational Geometry & Applications 11, 06 (dec 2001), 647–668.Google ScholarCross Ref
    8. J.Y.H. Fuh, M. W. Fu, and A.Y.C. Nee. 2004. Computer-Aided Injection Mold Design and Manufacture. CRC Press. https://www.crcpress.com/Computer-Aided-Injection-Mold-Design-and-Manufacture/Fuh-Fu-Nee-Fu/p/book/9780824753146Google Scholar
    9. Wei Gao, Yunbo Zhang, Diogo C. Nazzetta, Karthik Ramani, and Raymond J. Cipra. 2015. RevoMaker: Enabling multi-directional and functionally-embedded 3D printing using a rotational cuboidal platform. In Proceedings of the 28th Annual ACM Symposium on User Interface Software & Technology – UIST ’15. ACM Press. Google ScholarDigital Library
    10. Philipp Herholz, Wojciech Matusik, and Marc Alexa. 2015. Approximating Free-form Geometry with Height Fields for Manufacturing. Computer Graphics Forum 34, 2 (may 2015), 239–251. Google ScholarDigital Library
    11. Ruizhen Hu, Honghua Li, Hao Zhang, and Daniel Cohen-Or. 2014. Approximate pyramidal shape decomposition. ACM Transactions on Graphics 33, 6 (nov 2014). 1–12. Google ScholarDigital Library
    12. Masatomo Inui, Hidekazu Kamei, and Nobuyuki Umezu. 2014. Automatic detection of the optimal ejecting direction based on a discrete Gauss map. Journal of Computational Design and Engineering 1, 1 (jan 2014), 48–54.Google ScholarCross Ref
    13. Alec Jacobson, Ladislav Kavan, and Olga Sorkine-Hornung. 2013. Robust inside-outside segmentation using generalized winding numbers. ACM Transactions on Graphics 32, 4 (jul 2013), 1. Google ScholarDigital Library
    14. Wenzel Jakob, Marco Tarini, Daniele Panozzo, and Olga Sorkine-Hornung. 2015. Instant field-aligned meshes. ACM Transactions on Graphics 34, 6 (oct 2015), 1–15. Google ScholarDigital Library
    15. David O. Kazmer. 2016. Injection Mold Design Engineering. Carl Hanser Verlag. http://www.hanserpublications.com/Products/385-injection-mold-design-engineering-2e-ebook.aspxGoogle Scholar
    16. Rahul Khardekar, Greg Burton, and Sara McMains. 2005. Finding feasible mold parting directions using graphics hardware. In Proceedings of the 2005 ACM symposium on Solid and physical modeling – SPM ’05. ACM Press Google ScholarDigital Library
    17. Chang Ha Lee, Amitabh Varshney, and David W. Jacobs. 2005. Mesh saliency. ACM Transactions on Graphics 24, 3 (jul 2005), 659.Google ScholarDigital Library
    18. Weishi Li, R.R. Martin, and F.C. Langbein. 2009. Molds for Meshes: Computing Smooth Parting Lines and Undercut Removal. IEEE Transactions on Automation Science and Engineering 6, 3 (jul 2009), 423–432.Google Scholar
    19. Alan C. Lin and Nguyen Huu Quang. 2014. Automatic generation of mold-piece regions and parting curves for complex CAD models in multi-piece mold design. Computer-Aided Design 57 (dec 2014), 15–28.Google Scholar
    20. Linjie Luo, Ilya Baran, Szymon Rusinkiewicz, and Wojciech Matusik. 2012. Chopper: partitioning models into 3D-printable parts. ACM Transactions on Graphics 31, 6 (nov 2012), 1. Google ScholarDigital Library
    21. Luigi Malomo, Nico Pietroni, Bernd Bickel, and Paolo Cignoni. 2016. FlexMolds: automatic design of flexible shells for molding. ACM Transactions on Graphics 35, 6 (nov 2016), 1–12. Google ScholarDigital Library
    22. A.Y.C. Nee, M.W. Fu, J.Y.H. Fuh, K.S. Lee, and Y.E Zhang. 1997. Determination of Optimal Parting Directions in Plastic Injection Mold Design. CIRP Annals 46, 1 (1997), 429–432.Google ScholarCross Ref
    23. Alok K. Priyadarshi and Satyandra K. Gupta. 2004. Geometric algorithms for automated design of multi-piece permanent molds. Computer-Aided Design 36, 3 (mar 2004), 241–260.Google ScholarCross Ref
    24. B. Ravi and M.N. Srinivasan. 1990. Decision criteria for computer-aided parting surface design. Computer-Aided Design 22, 1 (jan 1990), 11–18. Google ScholarDigital Library
    25. Adrian Secord, Jingwan Lu, Adam Finkelstein, Manish Singh, and Andrew Nealen. 2011. Perceptual models of viewpoint preference. ACM Transactions on Graphics 30, 5 (oct 2011), 1–12. Google ScholarDigital Library
    26. Lior Shapira, Ariel Shamir, and Daniel Cohen-Or. 2008. Consistent mesh partitioning and skeletonisation using the shape diameter function. The Visual Computer 24, 4 (jan 2008), 249–259. Google ScholarDigital Library
    27. Olga Sorkine and Marc Alexa. 2007. As-rigid-as-possible Surface Modeling. In Proceedings of the Fifth Eurographics Symposium on Geometry Processing (SGP ’07). Eurographics Association, Aire-la-Ville, Switzerland, Switzerland, 109–116. http://dl.acm.org/citation.cfm?id=1281991.1282006 Google ScholarDigital Library
    28. J. Vanek, J. A. Garcia Galicia, B. Benes, R. Měch, N. Carr, O. Stava, and G. S. Miller. 2014. PackMerger: A 3D Print Volume Optimizer. Computer Graphics Forum 33, 6 (may 2014), 322–332. Google ScholarDigital Library
    29. W. M. Wang, C. Zanni, and L. Kobbelt. 2016. Improved Surface Quality in 3D Printing by Optimizing the Printing Direction. Computer Graphics Forum 35, 2 (may 2016), 59–70.Google ScholarCross Ref
    30. Miaojun Yao, Zhili Chen, Linjie Luo, Rui Wang, and Huamin Wang. 2015. Level-set-based partitioning and packing optimization of a printable model. ACM Transactions on Graphics 34, 6 (oct 2015), 1–11. Google ScholarDigital Library
    31. Chunjie Zhang, Xionghui Zhou, and Congxin Li. 2009. Feature extraction from freeform molded parts for moldability analysis. The International Journal of Advanced Manufacturing Technology 48, 1–4 (sep 2009), 273–282.Google Scholar
    32. Xiaoting Zhang, Xinyi Le, Athina Panotopoulou, Emily Whiting, and Charlie C. L. Wang. 2015. Perceptual models of preference in 3D printing direction. ACM Transactions on Graphics 34, 6 (oct 2015), 1–12. Google ScholarDigital Library

ACM Digital Library Publication: