Uncertainty of particle size measurements using dynamic image analysis.

Metal powder particle size distribution (PSD) is a critical factor affecting powder layer density and uniformity in additive manufacturing processes. Among various existing measurement methods, dynamic image analysis (DIA) instruments are very appealing for measuring PSD. However, the 'black box' nature and complex measurement process inherent to DIA make quantification of uncertainty challenging. A method to establish DIA-based measurement uncertainty based on calibrated powder samples via a scanning electron microscope is described. Uncertainty analysis was performed taking into account uncertainties associated with the calibration of the sample as well as non-similarities of the calibrated sample and the measured sample.