BAE Systems PLC
Superplastic forming and diffusion bonding process

Abstract:

A process and apparatus for forming a structure comprising: a) forming a pack from a skin sheet and a core sheet, wherein venting grooves are formed in a surface of a sheet that is adjacent to the other sheet; b) placing the pack in a mould and heating the pack; c) injecting a first gas between the core and skin sheets to urge the skin sheet against the mould; d) injecting a second gas on the side of the core sheet remote from the skin sheet to urge the core sheet against the skin sheet; e) maintaining gas pressure of the second gas thereby diffusion bonding the sheets; and f) withdrawing some or all of the first gas from the cavity.