'The University of Texas at Austin, Bureau of Economic Geology'
Abstract
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
