Designing an End Effector and a Thickness Adaptive Compression Molding Process for Wet Fiber Placement

Abstract

Wet Fiber Placement (WFP) is a manufacturing technology for continuous fiber-reinforced composites. It serves as an alternative to Automated Fiber/Tape Placement processes, offering cost-effective machinery and the programmability advantage of 3D printers. By bypassing pre-impregnated products, WFP enables the blending of preferred resins and fibers, providing enhanced geometric flexibility and material versatility. Two major challenges go along with this process strategy: (1) the freshly impregnated rovings tend to adhere to any surface they come in contact with, while (2) the impregnated rovings are slack and must be pulled rather than pushed all the way from the creel to the point where they leave the placement system. After placement, the generated “in-line prepreg” is consolidated and cured in a compression molding process, using an elastomeric/metallic, thickness-adaptive tool that can be used to process different workpieces with different thicknesses and workpieces with locally differing thicknesses in the same mold. This paper introduces a CNC system tailored for WFP, emphasizing the end effector’s components like pultrusion rollers, dancer modules, a cutting unit, and pre-consolidation elements. Despite successful roving placement, accuracy concerns persist, suggesting the need for sensor synchronization and cutting path optimization. Initial prepreg compression molding trials showcased thickness adaptability with minimal fiber displacement, offering potential for topology optimization, albeit demanding further parameter study to enhance product quality.