Does the Metal Powder Sphere Size Contribute to Metal Printed Part Quality?

Found this post on Metal Powder Quality and though it was pretty interesting, so much so, I decided to share it on my own blog. Credit however for this belongs to Louis Schlegel - Metal Printing Systems.

There are many emerging suppliers with different technologies producing metal powders with high quality materials. The metal printing industry welcome these suppliers to support the powder usage forecast and reduce powder costs through innovation and expanded competition. Per Stratasys, “Decidedly, metals are the most highly-coveted across all industries.” So What’s the Problem? Problem #1: % Oxide Content Under the same volume condition, smaller diameter spheres contain more oxide content compared to larger diameter spheres. The oxide thickness is within the same range regardless of sphere size but surface area mathematically demonstrates that smaller sphere sizes have significantly more oxide content compared to larger sphere diameters in a given volume. There is a sphere diameter oxidation threshold for each metal printed part specification. When a given layer contains a sufficient amount of smaller spheres below this threshold, the oxide content creates conditions leading to part quality issue. Do you cull your powder to address oxide content? This is one example why Fonon Corporation designs/manufactures specialized metal powder bed systems based on the part specification. When complex applications emerge, we customize the metal powder formula to eliminate this variable. I agree in advance that the metal powder delivered to the end-user should be in an enclosed, inert atmospheric state with no oxidation or moisture content. The possibility exists that the unused powder is subject to oxidation as it is recycled within the end-user's facility. This short series of posts is to probe into areas for improvement with respect to the metal powder's contribution to part quality.... Part I is a valid argument but may be limited in scope to highly complex applications/tolerances.....thanks!