A new manufacturing process developed by GKN Aerospace, makes it possible to create titanium structures from compound curves.

GKN Aerospace’s new ‘Delta pressure forming’ technique builds on the drape creep forming technique previously used by the company to create flat panels of titanium honeycomb sandwich. The new process uses an improved version of this drape creep forming process that substitutes the static weights for a roller system, to produce a cylindrical honeycomb barrel.

The cylindrical barrel is inflated into a die to create the required compound curvature. The operation is conducted in a vacuum furnace at temperatures exceeding 1500?F and the inflation pressure is provided by inert argon gas. Sophisticated forming analyses and special tooling features ensure the honeycomb core and the face sheets are not damaged during the process.

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.