TR2016-101

Strengthening ABS, Nylon, and Polyester 3D Printed Parts by Stress Tensor Aligned Deposition Paths and Five-Axis Printing


    •  Yerazunis, W.S., Barnwell III, J.C., Nikovski, D.N., "Strengthening ABS, Nylon, and Polyester 3D Printed Parts by Stress Tensor Aligned Deposition Paths and Five-Axis Printing", International Solid Freeform Fabrication Symposium, August 2016.
      BibTeX TR2016-101 PDF
      • @inproceedings{Yerazunis2016aug,
      • author = {Yerazunis, William S. and Barnwell III, John C. and Nikovski, Daniel N.},
      • title = {Strengthening ABS, Nylon, and Polyester 3D Printed Parts by Stress Tensor Aligned Deposition Paths and Five-Axis Printing},
      • booktitle = {International Solid Freeform Fabrication Symposium},
      • year = 2016,
      • month = aug,
      • url = {https://www.merl.com/publications/TR2016-101}
      • }
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  • Research Areas:

    Data Analytics, Optimization

In most fused filament fabrication systems, all filament laydown paths are at constant Z height. This creates a weak direction in the resulting parts, as the interlayer adhesion between melted and solidified material is much weaker than the tensile strength of the bulk material. For example, a hemispherical dome pressure vessel endcap will fail easily along these Z=constant cleavage planes. We resolve this problem by proposing a 3D printing system that does not limit the nozzle positioning to a single Z layer at a time, or to constant pitch and yaw angle, but instead lay down extrusions more closely aligned with the stress tensor within the part (but requiring 5 simultaneous axes of motion). To verify this, we have constructed a working 5-axis fused-filament fabrication 3D printer and produced a number of test parts in ABS, nylon 645, and T-glase polyester. Using a commercial hydrostatic pressure system, we have tested these parts to destruction and find a typical strength improvement of 3x to 5x over conventional 3-axis parts printed to the same specification, in the same machine, from the same spool of polymer; the only thing changed was the extrusion pattern. An approximate calculation to translate this into the material's ultimate tensile strength shows that the 5-axis FFF parts are within a factor of two of the ultimate tensile strength of typical professionally injection-molded ABS material.