Improved resin transfer moulding for planes

Citation

(1998), "Improved resin transfer moulding for planes", Aircraft Engineering and Aerospace Technology, Vol. 70 No. 3. https://doi.org/10.1108/aeat.1998.12770cab.034

Improved resin transfer moulding for planes

Improved resin transfer moulding for planes

Keywords Aircraft industry, Moulding, Resin transfer moulding, Resins

A US company, Dow-United Technologies (Dow-UT) Composite Products Inc. in Wallingford, Connecticut, has been awarded a $30.2 million contract to build structural composite parts for the US Air Force F-22 fighter, using an improved resin transfer moulding (RTM) process. The contracts, which run until the end of 1998, cover the manufacture of a range of components for the first nine F-22s, which are being built by Lockheed Martin Aeronautical Systems and the Boeing Defence and Space Group's military division. Approximately 150 RTM parts per aircraft will be incorporated in the forward fuselage, vertical and horizontal tails, edges, and wings.

Resin transfer moulding is used to fabricate fibre-reinforced resin composite parts (such as the wing spar) that are lightweight and strong. Dow-UT, a joint venture between Dow Chemical Co. and United Technologies Corporation, developed the proprietary advanced RTM process, which results in greater quality, increased production rates, and an ability to manufacture more complex parts than in the past.

Standard RTM techniques are labour-intensive: components are typically assembled one piece at a time by hand-fitting woven-fibre plies into a mould. Dow-UT has automated most of the process, including applying powdered resin to the fabric, cutting, lay-up, and moulding. The refined process can produce more complex parts than was otherwise possible with preimpregnated (prepreg) materials ­ net-shape finished parts that require minimal machining. This means that several components can be integrated into one piece, which lowers part counts and reduces assembly time. Also, parts can be made with a defined resin content, with plies oriented to critical specifications and very low void content.

The raw materials for the improved RTM process generally cost less than those used in more traditional prepreg moulding. Dow-UT's in-house fabric looms also help reduce cost and maintain quality control from fibre to fabric to finished product. Significant cost savings are realized by the increased yield on complex parts.

Advanced RTM composites are said to be appropriate for the speciality car industry, and in recreational and industrial applications where annual production is in the range of 10,000-15,000 parts. The new process will be used, for example, in an attempt to build cost-effective composite flywheel motors for future electric and hybrid vehicles.