LARGE-SCALE AIRCRAFT STRUCTURES THROUGH OUT-OF-AUTOCLAVE PROCESSES

LARGE-SCALE AIRCRAFT STRUCTURES THROUGH OUT-OF-AUTOCLAVE PROCESSES  

The manufacture of large primary aircraft structures using composite materials has expanded over the last decades, but it relies on autoclave curing, and this involves high energy consumption, operational costs and lead times. This has led to increased interest in material and process technologies that favour high-rate, highly-automated out-of-autoclave (OOA) processes.  

The Full-scale innovative Integrated Tooling for COmposite material Wing-box (FITCoW) project has set out to design, manufacture and test a tooling system that can reduce the recurring costs of low-volume production, and reduce its carbon footprint, through the use of suitable materials and techniques for OOA manufacturing. FITCoW is a key component in the OPTICOMS (Optimised Composite Structures for Small Aircraft) project, funded by Europe’s Clean Sky 2 programme, which is evaluating the design of a low-volume wing-box that features automated fabrication, integrated structures, structural bonding, novel manufacturing and assembly tooling procedures. OPTICOMS is trying to achieve these technological milestones through a cost-effective OOA approach.  

Novel tooling system 

FITCoW’s task is to develop a composite tooling assembly capable of co-curing four different primary structural aircraft components (three spars and the upper wing skin) into a single, 7 m-long carbon fibre reinforced polymer (CFRP) wing box.  

The tooling system is being designed to:  

• enable co-polymerisation and allow both liquid resin infusion (LRI) and prepreg manufacturing;  
• be compatible with both automated tape laying (ATL) preforms and hand lay-up;  
• mitigate coefficient of thermal expansion (CTE) mismatches between the part and tooling;  
• ensure assembly stability under vacuum pressure;  
• withstand and maintain structural stability at high temperatures (up to 185°C);  
• minimise the risk of human error wherever possible;  
• allow robust manipulation of tooling in the manufacturing premises;  
• ensure good surface quality of the resulting parts.  

Lower manufacturing costs 

The tooling system allows for an increased volume of work at a decreased cost, with less time and energy spent during the manufacturing process as well as minimal material waste. This has a direct impact on carbon emissions, and costs. 

FITCoW has set ambitious targets for these improvements, including:  

• up to 50% lower manufacturing cost per produced part;  
• 30% tooling cost reduction when compared to conventionally-deployed metallic tooling;  
• 20% manufacturing time reduction when compared to current autoclave processes.  

Learn more about the tooling design, materials used, and some of the challenges the project faced, in the April-May 2022 issue of JEC Composites Magazine (FITCoW – Co-polymerising large-scale structures through OOA processes).  

Want to know more? Log in to your JCM account or register for a free subscription here:  

https://www.nxtbook.fr/newpress/jeccomposites/jcm2204_145/index.php#/p/26