EVALUATION OF METAL LATTICE STRUCTURES WITH X-RAY MICRO-COMPUTED TOMOGRAPHY: DIMENSIONAL ACCURACY AND MANUFACTURABILITY

摘要

Additive manufacturing enables product designers to incorporate complexity onto their designs on multiple size scales. Computer-aided design methods, such as topology optimization and lattice design, have emerged as software tools for applications where part consolidation and weight reduction are desired. Still, a more delicate control of hierarchical complexity and submillimeter-sized features would unlock a widely unexplored frontier of new design possibilities. However, the complexity of a design can respectively affect the manufacturing process. In powder bed fusion, the diameter, power and speed of the laser spot and the resulting size of the melt pool define the attainable feature resolution and accuracy in comparison with the original design intent. X-ray computed tomography can be a useful tool in validation and provide a detailed, volumetric representation of a part with internal features. This paper examines the design accuracy of 316L metal lattice structures and density of solid cubes with industrial X-ray micro-computed tomography. Accessible tools with open source software are presented for CT data analysis. The nominal values are compared against the as-built and CT scanned samples for surface area, volume, and dimensional accuracy. A CT voxel size of 50 - 40 μm allows to identify print ability issues and general trends in the part density in comparison to the geometry changes. However, a finer voxel size in the submicron range would be required to properly detect and localize internal porosity and evaluate surface topography.