Process Intermittent Measurement for Powder-Bed Based Additive Manufacturing

Process intermittent measurements of parts fabricated by additive manufacturing (AM) can enable both process improvement and characterization of internal part geometries. The planar, layer-upon-layer nature of most AM processes allows two-dimensional geometric measurements with a vision system, because the part’s current layer is continually in focus. Proof of this concept has been shown through measurement of parts made using a three-dimensional (3D) printer. Process intermittent measurements were compared to contact and non-contact measurements of the finished parts to characterize deviations in printed layer positions and changes in part dimensions resulting from post-process treatments.Mechanical Engineerin

Variation of Emittivity with Powder Bed Fusion Build Parameters

Common approaches to process monitoring of powder bed fusion rely heavily on optical measurements. These measurements can be used to verify powder spreading, assess the quality of each layer, and measure process temperatures. In regards to the latter, radiometric detectors such as cameras or pyrometers only measure radiant emissions from the surface, and do not directly measure its temperature. Calculating the temperature from these measurements relies on the calibration of the camera or pyrometer with a blackbody and on knowledge of the emittivity of the surface being measured. Emittivity depends on multiple factors including surface texture and viewing angle, among others. An apparatus and method for measuring emittivity using an infrared camera is detailed. Measured emittivity values from metal surfaces produced using a commercial powder bed fusion process are presented and related to temperature, viewing angle, and oxidation state.Mechanical Engineerin