Rapid forming of commingled thermoplastic composites via induction-heated CFRP molds

Abstract

Conventional metal tooling for thermoplastic composite processing has a high density and thermal mass, resulting in long cycle times that exceed 60 min. This work presents a rapid forming approach using induction-heated carbon fiber-reinforced plastic (CFRP) molds with low thermal mass and minimal thermal expansion. However, the anisotropic and low thermal conductivity of CFRP causes significant non-uniform heating with conventional spiral coils. To address this issue, a ‘zig–spiral’ hybrid coil pattern was designed through coupled electromagnetic–thermal simulations, reducing temperature variation to below 6 °C, even for curved geometries. The coil design was experimentally validated through vacuum-bag forming of 3.3 mm-thick commingled yarn PP/GF laminates, resulting in uniform consolidation. Using this process, the total cycle time was reduced to 19 min (68 % faster than compression molding), and the tensile and flexural strength were maintained at 95 %. These results demonstrate the viability of induction-heated CFRP tooling as an efficient and scalable solution for manufacturing thermoplastic composites.