Effect of Measurement and Sampling Strategy in Surface Analysis of Laser Powder Bed Fusion Additive Manufacturing of Nickel Superalloy 625
Jason C. Fox, Adam L. Pintar
As parts built through additive manufacturing (AM) increase in complexity, the development and understanding of appropriate methods to characterize the as-built surface will be required. In laser powder bed fusion (LPBF) AM, parts are built through a complex process with size scales that include single/sub-micrometer (e.g., cracks and fine topographic features on the part surface), tens of micrometers (e.g., feedstock powder diameters and layer thicknesses), hundreds of micrometers (e.g., laser scan hatch spacing and melt pool dimensions), single/tens of millimeters (e.g., laser scan stripe widths), and tens/hundreds of millimeters (e.g., part dimensions). This large range and complexity of the build process creates surfaces with complex topographies, large height ranges, and steep slopes when compared to machined surfaces and, therefore, uncertainty that a measurement sufficiently portrays the full surface from which it was sampled. With these aspects in mind, the goal of this work is to better understand the measurement and sampling strategy to aid development of measurement routines for AM parts. Currently, no recommendations exist for defining the required point spacing, size of measurement regions, or number of measurement regions required to adequately describe the as-built AM surface. In this work, a relatively large AM part is built in nickel superalloy 625 using a commercially available LPBF system to create a planar surface greater than 40 mm x 40 mm in size. The large surface area measurement was subdivided in to regions similar in size to single and stitched FoV measurements to assess variation in areal surface parameters across the surface their ability to statistically represent the entire surface. The result of this work provides an important step in developing guidance for the measurement of as-built AM surfaces.
Proceedings of the 2019 Special Interest Group Meeting: Advancing Precision in Additive Manufacturing
September 16-18, 2019
Special Interest Group Meeting: Advancing Precision in Additive Manufacturing