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Powder specifications for Binder Jetting

Developing an effective metal powder specification for Binder Jet Additive Manufacturing Powder specifications vary significantly across the various metal Additive Manufacturing technologies. As Andrew Klein, Director of R&D at The ExOne Company, and Jamie Clayton, Operations Director at Freeman Technology explain, powders for Binder Jetting in particular have very specific process-related requirements. In the following article, the two offer their insight into the rapid assesment and qualification process for a new 316L stainless steel powder.

Binder Jetting is an established metal Additive Manufacturing technology with notable advantages relative to other AM processes. Build times tend to be relatively fast and large-scale structures are readily manufactured. Binding powder layers during processing, rather than thermally fusing them, avoids the build up of residual stress in the finished component. As demand for this cost-effective technology grows, it becomes increasingly important to broaden the range of qualified metal powder feedstocks available. ExOne, based in Pittsburgh, Pennsylvania, USA, is a global leader in Binder Jetting technology, providing machines, AM products and related services. The company routinely faces the challenge of assessing new metal powders from customers to determine how the technology will perform for a given application and is actively engaged in qualifying new materials. This article looks at how ExOne has learned to differentiate powders that will perform well from those that will not, and the pivotal role of powder flow measurements in defining specifications.

Vol. 5 No. 2 Š 2019 Inovar Communications Ltd

An introduction to Binder Jetting In the Binder Jetting process, a recoater and roller spread fine layers of metal powder across the build plate. The printhead then releases droplets of polymeric binder into the powder bed to selectively bind

defined areas, and the build plate is subsequently lowered in readiness for spreading another layer of powder. Binding successive layers of powder progressively builds a green part or body which is removed from the build box for further processing. Metal powder not bound into the finished component, typically around 95% of the powder feed, is recycled.

Fig. 1 Binder Jetting is a flexible, cost-efficient process for manufacturing complex components to high resolution

Metal Additive Manufacturing | Summer 2019

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