Metrology of Dimensional Variation in Titanium Electron Beam Melting Additive Manufacturing and the Impact to Manufacturing Repeatability

The aerospace industry has been investing in metal additive manufacturing for the benefit of being able to print parts that are lighter weight and more capable than those manufactured with traditional methods. High quality serial production is important in this industry as it directly impacts product safety; therefore, the manufacturing repeatability of additively manufactured components has to be proven before wide implementation. Electron Beam Melting (EBM) is one form of additive manufacturing capable of producing fully dense titanium components where an electron beam is used as the energy source to selectively melt Ti-6Al-4V powder within a build chamber to produce a 3-dimensional part. This technology promises designers the freedom from the design constraints imposed by traditional manufacturing techniques. Several experiments were conducted to capture sources of variability that may impact the manufacturing repeatability of parts. The default scan strategy of an Arcam A2X was investigated while producing line, stair, and ramp specimens with Ti-6Al-4V powder. From these experiments, 4 mm long single beam line specimens, as well as 140 mm long shallow stair and ramp specimens that varied in thickness from 100 µm to 1.4 mm were fabricated. Due to the layering of the powder bed fusion process, the ramps were designed to capture the staircase effect and reveal the hatch scan and quality of each layer. Repetition of these specimens for manufacturing repeatability within the same build revealed sources and magnitudes of variability where no two specimens were identical. All metrological results point to process parameters that can be sources of variability even within the same build. This serves as vital information for any additive manufacturing designer who must design for the EBM process and understand how the parameters can affect their product geometry. The experimental results of this study will be shared in this presentation.