Refined additive manufacturing processes and new materials are increasingly facilitating the fabrication of more sturdy workpieces; the cost-effective, rapid process is therefore being exploited in more and more fields of application, including now also the 3D printing of high-strength TRIP steel alloy components . The Fraunhofer Institute for Manufacturing Engineering and Automation IPA recently presented a new process for the fabrication of 3D-printed workpieces with injection molding properties called ‘additive free-mold casting’. This process aims to produce small series and prototypes faster and more cost effectively than mere injection molding – with, at the same time, better material properties than those of other FLM (Fused Layer Modeling) parts. Instead of comparatively softer thermoplastics, more heat-resistant thermosetting plastics are used here. Moreover, there are no structural instabilities, since workpieces can be produced without weld lines and porosity.
The FLM process is used only to print a water-soluble polyvinyl acetate sleeve for the object being manufactured. In a next step, this sleeve is filled with fast-curing polyurethane or epoxy resin. Where very big objects are to be produced, the process is repeated as many times as required. Finally, the workpiece mold is removed as soon as the workpiece has fully cured in the water bath. A dosing unit for two-component materials, also recently developed, is used in the 3D printer. This means that the printing and casting processes are fully automated in the printer.
The Fraunhofer IPA is currently seeking partners from industry to further improve the process and tailor it to the relevant specific requirements.