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Study of Infill Pattern and Backfill of Low-Cost 3D Printed Polymer Tooling for Sheet Metal Forming Applications

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  • schoolOptimization

3D printed polymer tooling is very attractive for tooling design, especially in low-volume manufacturing and production prototyping, due to its lower cost, shorter lead time and higher design flexibility compared to traditional metal tooling. Instead of printing solid tooling, using a sparse infill and backfill strategy can further decrease printing time and total manufacturing cost. The primary concerns with polymer tooling for metal forming is sufficient tool strength and stiffness. In this work, the effects of two polymer materials, three infill patterns, three shell thicknesses and two backfill materials were studied on the compressive properties of fabricated parts. Commercial 20% carbon fiber reinforced ABS (CF/ABS) and 20% glass fiber reinforced Polycarbonate (GF/PC) from SABIC were selected as tooling materials due to their high mechanical properties. Epoxy and cement were selected as backfill material based on their low cost and good mechanical properties. CF/ABS and GF/PC pellets were printed on a Cincinnati Inc. medium area additive manufacturing (MAAM) 3D printer using melt extrusion method. Its build envelope is 1m×1m×1m and max printing speed is 2.5 kg/hr. Compression test of backfilled filled polymer samples showed that samples of CF/ABS with grid infill pattern and epoxy backfill have highest compressive properties. These results provide design guidelines for full-size 3D printed tooling. Lastly, 1.5 mm steel sheet metal components were stamped using solid CF/ABS tooling. Twenty pieces were successfully formed without any observed damage to CF/ABS tooling. With proper infill pattern and backfill, the estimated cost reduction is 95% versus traditional metal tooling. 

Learning Objectives:

  • Upon completion, participant will learn application examples of how the automotive industry is utilizing large-scale polymer AM tooling.
  • Upon completion, participant will understand cost reduction opportunities using backfill mold techniques in combination with polymer AM.
  • Upon completion, participant will learn the printability of carbon fiber reinforce ABS pellets on the Cincinnati Inc large-scale 3D printer.

Sponsored by:   stratasys.png

  • Dan Zhang
    Postdoc Researcher
    Center for Design and Manufacturing Excellence, The Ohio State University