Automated fiber placement of pre-impregnated (pre-preg), thermoset carbon materials has been industrialized for decades whereas dry-fiber carbon materials have only been produced at relatively low rates or volumes for large aerospace structures. This paper explores the differences found when processing dry-fiber, thermoset, carbon materials (DFP) as compared to processing pre-preg, thermoset materials with Automated Fiber Placement (AFP) equipment at high rates. Changes to the equipment are required when converting from pre-preg to dry fiber material processing. Specifically, the heating systems, head controls, and tow tension control all must be enhanced when transitioning to DFP processes. Although these new enhancements also require changes in safety measures, the changes are relatively small for high performance systems.
Processing dry fiber material requires a higher level of heating, tension control and added safety measures. However, once these are achieved, processing rates and reliability may be significantly improved for DFP versus traditional pre-preg AFP processing. Overall payout speeds as well as steering speeds can be increased for dry fiber resulting in increased laydown rates when using current AFP processing techniques. The lack of resin within the material greatly reduces resin build-up, which supports longer maintenance intervals and greater reliability by minimizing or eliminating the problems associated with resin build-up. The controlled emission area and fast response time of precision heating systems greatly reduce unwanted heat on surrounding areas and increase process performance. In addition to DFP, further developments in the heating system have also proved beneficial for thermoset as well as thermoplastic processing. All of these advantages increase the machine utilization as well as reliability when processing aerospace parts made from dry fiber materials with AFP equipment.
