A gradient-based deformation compensation method for minimizing warpage in sintered binder jetted parts

Principal investigator: Albert To

University: University of Pittsburgh

Industry partner: Wabtec, ExOne and Ansys

Binder jet printing (BJP) enjoys high material deposition rate, low-cost feedstock, negligible residual stress, and self-supporting parts compared to other powder bed metal additive manufacturing (AM) processes. These unique advantages make BJP attractive to the manufacturing industry, especially for manufacturing large and complex parts with high resolution. However, one critical issue that hinders the broad adoption of BJP is the significant warpage introduced during post-sintering of jetted parts. A practical solution is to employ the so-called “deformation compensation” method, in which the original design geometry is modified so that the compensated model deforms to the target shape after fabrication (i.e. printing and sintering). However, existing deformation compensation methods have a loose parameter that needs to be tuned empirically to obtain satisfactory result for different geometries. To overcome this issue, the project team will develop a gradient-based deformation compensation method without any tuning parameter for designing sintered BJP parts. The research tasks include: 1) Mature the sintering model for complex BJP parts, 2) Extend the reverse shape compensation method to treat 3D parts, and 3) Experimentally validate the reverse shape compensation method. Near the end of the project, PITT will share the developed design tool with our western PA industrial partners Wabtec, ExOne, and ANSYS, and train their engineers to use it. The developed method is expected to yield sintered binder jetted parts with much less warpage than other existing methods. This would ultimately lead to significantly smaller upfront costs, waste, and lead-times for binder jetted parts. The PITT student fellows supported through this project will work closely with engineers from the industrial partners through internship and will leverage their expertise in binder jetting and computational modeling. The close interaction with the industrial partners is expected to lead to high-paying employment opportunities for the students involved after the project.