GKN DEVELOPS NEW FORMING PROCESS
15 Jul 08. GKN Aerospace – Santa Ana, is now delivering the first production hardware manufactured using an entirely new process that will form compound curves into titanium structures for the first time. Marcus Bryson, Chief Executive Officer, GKN Aerospace comments: “Our new ‘delta pressure forming’ process represents an important manufacturing development. It complements our
existing titanium manufacturing capability, allowing us to bring the performance benefits of this metal to a great many more severe environment applications across the aero-engine – with resulting improvements in durability and engine weight and reductions in fuel consumption, emissions and noise.” The Company is already successfully using the new process to manufacture the advanced cone-shaped titanium exhaust system for the Boeing 747-800, which commenced delivery early this year. The process will also provide an effective method to create the complex shapes required for extremely rugged items such as engine inlet lips and inner barrels, thrust reverser inner fixed structures and exhaust nozzles and plugs. Titanium products combine minimal weight with maximum strength and excellent sustained performance in severe environments. GKN Aerospace’s established, proprietary, resistance welded and diffusion bonded ‘Soundwich R’ technology produces flat panels of titanium honeycomb sandwich with excellent noise suppression qualities. Until now, these panels are formed to the shape of the final product using GKN Aerospace’s drape creep forming technique. In this process, the flat panel is draped around a die in a vacuum furnace at temperatures well above 1000 degrees F with static weights attached to the ends of the panel. This creates a straight cylindrical or conical shape.
The GKN Aerospace team in the Company’s Composites Research Centre is in the final stages of work on the three year Integrated Wing, Advanced Technology Verification Programme (IW-ATVP) which is trialling multiple new manufacturing processes for composite aircraft wing ribs, skins and spars. Frank Bamford, Vice President Business Development, of GKN Aerospace comments: “The Integrated Wing programme is a key element in a matrix of research and development activities through which our team is developing new manufacturing methodologies designed specifically for composite assemblies rather than adapting traditional processes developed for metallic structures – as has largely been the case across the industry to date.2
By the end of 2008, using innovative processes such as automated tape laying, hot drape forming, microwave curing, self heated tooling, composite fastening and melding, the Company will have produced a full ‘closed cell box’ demonstrator. Closed cell box sections are found in assemblies such as wings, vertical and horizontal stabilisers, flaps, ailerons, elevators and rudders and form a major part of the aircraft structure, often making up some 30 % of the airframe weight. Automated Tape Laying (ATL) of carbon fibre tape is already producing an over 75% reduction in man hours compared to manual methods. Hot drape forming will convert the flat stack of composite material to a complex formed component. Out of autoclave curing aims to eliminate the size limitations, and manufacturing bottleneck, inherent in using an autoclave to cure the final item. Microwave curing offers an environmentally friendly alternative to autoclaves by using much less power and potentially opens up new joining methods. And composite fasteners are being tested to compare with traditional metal items for weight, lightning strike compatibility and cost.
As part of the range of research and development activity focused on composite
manufacture, GKN Aerospace is also involved with the recently launched ‘Next Generation Composite Wing’ (NGCW) research programme. In this complementary activity, the Company is working with 16 other leading British indus