This research successfully establishes a proof of concept for the hot forming of PEEK sheets using resin-printed polymer molds.
Mechanical metamaterials, through their architected inner structures, offer unique properties that enable unparalleled functionalities. In the MECOMOS project, a novel manufacturing method is proposed to fabricate a multi-stable 3-DoF PEEK metamaterial that enables tip, tilt, and z-translation. The method involves forming PEEK layers to create the geometries of the unit cells, followed by joining these formed layers to produce a monolithic metamaterial.
In this research, a new forming method, hot forming, is developed and analyzed for shaping these layers. This method creates microscale features in PEEK sheets by implementing the process steps of hot embossing into matched die thermoforming.
Polymer molds with various geometries, including rounded cylinders, blocks and trapezoids, are successfully resin printed. Key variables influencing the mold output in resin printing include the cleaning procedure, post-curing, and layer thickness. The smallest printable features measure 400x400x100 µm, and the printing errors range from 40 to 150 µm and are predominantly independent of feature size.
The proof of concept for the hot forming process reveals its strong potential as a manufacturing method.The forming parameters are highly forgiving, with a broad range of process parameters still yielding high replication quality. The suitable forming temperature spans from 100 to 150°C, and pressing forces between 750 and 3000 N prove effective.