From Polymer to Powder: Investigating the Additive Manufacturing Recycling Process

Additive Manufacturing (AM) is a term used to describe advanced production methods that convert a 3D model into a real part by the layer upon layer addition of material. Compared to traditional subtractive methods, AM is ideal for rapid prototyping and can enable the faster, cheaper and more efficient production of complex parts such as customized medical components or engine parts, often with improved strength and durability.

As illustrated in Figure 1, Powder Bed Fusion (PBF) processes involve the controlled application of a thin layer of powder, followed by the use of a thermal source such as a laser to selectively fuse the powder particles together. This is repeated for each layer and the finished part is then extracted from the powder cake. The unused powder can then be recycled for the next part, usually by blending it with a certain amount of virgin powder. Thermoplastic polymers such as polyamide 12 (known commonly as nylon 12 or PA12) are well suited for PBF processes as they can be processed reliably due to their semi-crystalline nature providing a distinct melting point. 


Figure 1. Diagram showing a typical Powder Bed Fusion (PBF) process

The ability to recycle unused powder gives PBF processes the potential to be very resource-efficient, but this efficiency depends strongly on the condition of the recycled powder, as it risks a deterioration in final part quality. This Application Note looks at how size exclusion chromatography (SEC), which determines the macromolecular characteristics of the feed material, and automated image analysis, which provides morphological information for the particles, can provide valuable insights to this active area of research.

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