Amorphous materials have a disordered molecular structure with no repeating pattern. This lack of order at the molecular level often gives the material its main advantages in AM. These include ease of processing, smooth surface finish and transparency.
The thing is most amorphous polymers are processed through FDM 3D printing.
BlueSky Polymers, Insight Polymers and Advanced Laser Materials (ALM) have developed an amorphous, reactive polyetherimide (xPEI) engineered specifically for selective laser sintering (SLS).
ALM brings to this development its expertise in powder modification, scaling powder production and optimizing the various process conditions for successful SLS printing.
According to the developers, SLS-printed xPEI offers isotropic properties for high-value, high-temperature production applications. Insight Polymers’ Mathew Torosian describes consistent properties in the X, Y and Z directions. The companies claim that SLS-printed xPEI parts offer the highest heat resistance, chemical resistance and tensile strength of any SLS thermoplastic. Until now, PEI had not been suitable for SLS printing of amorphous high-temperature parts, the companies explain. They attribute this to high melt viscosity and limited interlayer diffusion.
“Our chemistry will allow users to design parts using high-performance polymers that can be printed on existing SLS and FDM (Fused Deposition Modeling) systems, which until now has not been possible,” said Theo Dingemans, chief technology officer of BlueSky Polymers and professor at UNC Chapel Hill.
Chemistry that enables production on existing SLS and FDM systems.
Based on the Sabic Ultem™ backbone, xPEI is available as a reusable powder for SLS and as filament for FDM. The companies describe xPEI as offering low flammability, excellent fluid stability, a low carbon footprint and an unlimited shelf life.
A controlled thermal cure follows SLS and FDM printing. It increases the glass transition temperature, yields consistent mechanical performance and reduces part variability.
“The xPEI polymer is targeted for parts that need strength, stiffness and impact resistance of a PEI polymer but are too difficult to produce by injection molding or subtractive manufacturing,” said Matt Torosian, Insight Polymers sales and market development manager.
Torosian (ex-JABIL) highlighted potential applications across a wide range of industries. They include air handling and ducting in aviation; exterior skin components for drones and missiles. Other applications include fluid handling and cooling systems in data centers, and test sockets and other high-temperature applications in semiconductors.
In addition, he spotlighted, “surgical tools and medical devices that require sterilization and medical devices with strength and stiffness of a PEI polymer” that are too hard to produce. Further, the xPEI polymer “allows for the production of parts with isotropic properties, with excellent consistency to fit into those applications,” said Torosian.
Insight Polymers & Compounding, an expert in advanced polymer compounds, is now producing xPEI in multi-kg quantities.
Jeremy Lizotte, Insight Polymers director of innovation, also highlights the design freedom SLS offers compared with injection molding and subtractive manufacturing. He also points to the potential to reduce material use by avoiding machining waste.
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