Induction Heating Technology for SPF/DB of Titanium Sandwich Panels

The use of induction heating with smart susceptors and cast ceramic tools as applied to superplastic forming and diffusion bonding (SPF/DB) of titanium structures holds a number of processing advantages.  These advantages include: lower tooling costs, improved control of dimensions, exacting control of the process for improved repeatability, the ability to automate and control loading and unloading, plus loading and unloading cold allows the control of the part environment, therefore, reducing part and tooling oxidation.  The basis of the concept is to use cast ceramic tools with integrally cast induction coils and ferromagnetic smart susceptor die liners.  The ceramic tool does not heat inductively and allows the magnetic field to act directly on the smart susceptor die liners.  These smart susceptor liners heat rapidly to the Curie point and then provide thermal leveling at the Curie temperature.  This lower tool mass and good thermal control help to provide the desired processing advantages.