HEATED ADDITIVELY MANUFACTURED MOLDS FOR THERMOPLASTIC COMPOSITE AUTOMATED FIBER PLACEMENT

Abstract

Thermoplastic composite (TPC) tapes can be consolidated in situ via automated fiber placement (AFP) at relatively high temperatures (>250°C) and local pressures (up to a few MPa). In situ consolidation of TPC parts requires special tooling and heated molds to prevent warping. Creating complex three-dimensional (3D) molds at a low cost and in a short time frame can facilitate TPC AFP adoption and entry into new markets requiring customized parts. The industry standard for mold manufacturing is milling or bending metal stock (typically invar, steel, or aluminum). This process can be costly and have lead times upwards of two months. Additive manufacturing can shorten the lead times significantly. Additively manufactured molds, to be used by TPC AFP, should withstand high temperatures and roller pressures. Current mold generation practices do not have a method of heating the mold surface necessary for dimensional accuracy of TPC tape-based parts. This paper investigates a process to create 3D molds via fused filament fabrication (FFF), a form of material extrusion additive manufacturing (AM), and high-performance materials that can withstand the temperatures and pressures of thermoplastic AFP application. FFF offers customized parts quickly and at a low cost. A laser-assisted AFP robot performed a layup over two heated FFF molds made of short carbon fiber reinforced polyetherketoneketone (CFPEKK), a flat plate and one with a one-axis curvature. These specimens performed well with no noticeable permanent deformation of the mold caused by either the roller or the laser demonstrating the viability of this mold generation process to create 3D molds usable with TPC AFP.