At electron beam powder bed fusion (EB-PBF): A novel method for generating one single layer of powder and calculating their actual packing density with the assistance of White-light interferometry
Despite the wide applications of powder metallurgy in the field of additive manufacturing AM, knowledge on spreadability of powder particles in electron beam powder bed fusion (EB-PBF) is lacking. This study provides a comprehensive literature review for powder characterization, flowability, and spreadability for AM processes. Different flowability tests are discussed in detail according to their mechanisms. Powder spreading mechanisms for different powder-bed AM are reviewed. Furthermore, a technique is proposed to study spreadability in which a single layer of powder is spread by a standard method, ‘frozen’ in the as spread condition by ‘contact sintering’ and then characterized using white-light interferometry. As a result of this technique, a standard method to calculate the powder-bed density is defined clearly, and correlations between powder-bed density and packing factor, spreadability and flowability are established. Finally, the mechanism of contact-sintering is utilized successfully as a powerful tool to differentiate between powder lots according to their packing density values.