THE CHALLENGE
Ultra-high molecular weight polyethylene is really viscous and hard to process, so it can’t be used for injection molding.
Chris Williams and his lab have developed a novel scan strategy that allows for the use of polymers that are much more viscous than are normally compatible with 3D printers. They allow space between the laser sintering lines, and then the post processing fixes the spaces. Post processing is essentially heating the part to just above the melting point of the polymer and letting the layers melt a little. Since the polymer is so viscous, the part doesn’t irreversibly melt into a puddle of sad.
Schematic example of scan strategy. On the far left is the input shape; the middle and right show the first and second layer scan patterns.
Example of parts printed using the novel scan strategy. A: green parts as they look when removed from the printer. B: parts after post processing.