Expanding the Range of Powders Used in Direct Metal AM

Currently, powders used in direct metal additive processing are restricted based on maximum and minimum particle size.  Even if maximum and minimum particle size standards are adhered to, AM machine users are hesitant to use powders from a variety of vendors, due to different distributions of particle sizes, particle shapes, and particle roughnesses.  As a result, there is a severe restriction in AM powder feedstocks currently in use.  This talk gives an overview of a research seeking to expand the range of powders used in both laser powder bed and electron beam powder bed processes.  The focus is on the use of powder systems with larger maximum particle sizes, which can be significantly less expensive than standard systems.  Powder properties are measured, including particle size and shape distributions and flow properties.  Where needed, AM process variables are altered to allow successful powder spreading, powder sintering and powder fusion.  Results will be presented over seven different powder systems of Ti64 and IN718.  One of the successfully used powders has particle diameters much larger than what are normally used in electron beam powder bed processes, substantially broadening the range of powders available to users.  In another case, a Ti64 powder system consistent with an e-beam powder bed standard is used in a laser powder bed machine.  Results demonstrate that there is a “powder space” that is useable in existing AM machines, but is largely unexplored and not yet exploited.