Optimizing a Lattice Based Raft for Decoupling Thermal Stress to Reduce L-PBF Build Plate Warping During Additive Manufacture of GRCop-42 Cu-Cr-Nb Copper Alloy
Description
Laser Powder Bed Fusion (L-PBF) is a key enabling technology for rapid Additive Manufacturing (AM) of complex part geometries unachievable with traditional manufacturing techniques. AM of a high field side (HFS) lower hybrid current drive (LHCD) launcher was successfully demonstrated using Laser Powder Bed Fusion (L-PBF) of Glenn Research Copper 84 (GRCop-84). Coefficient of thermal expansion (CTE) mismatch between GRCop-84/42 and steel or Inconel build plates resulted in modest, though measurable, warping. Support structures called rafts provide a platform to decouple thermal stresses at the build-plate-component interface. An LCD-based stereolithography (SLA) photopolymer resin printer was used to rapidly optimize raft designs using a low-cost platform. Contraction of the photopolymer during curing produced volumetric reduction driver strain analogous to CTE-mismatch strain during LPBF. Raft geometries comprised of a lattice of cones, hexagons, triangles, and squares were optimized to minimize build-plate curvature. Raft solutions found with SLA to minimize build plate curvature and improve accuracy will be implemented in future L-PBF trials to reduce warping due to thermal stress.
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Steps to reproduce
Raft structure designs and test blocks were printed using recommended slicing parameters for Anycubic Water Wash Resin+ on an Anycubic Photon M3 Plus printer with the settings described in the paper. A magnetic adhesive base and flexible magnetic build plate allowed detachment of the build plate for measurement. An in-house coordinate measurement machine profiled the height across center of the detached build plate and is plotted with the code provided with the dataset. A circular function was fitted onto smoothed and median filtered profile data to extract curvature values for a measure of the raft structure's performance.
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Funding
United States Department of Energy
DE-SC0014264