Series parts manufacturing by Infrared Superplastic Forming with numerical techniques for thermal regulation.

The Superplastic Forming (SPF) has wide applications in variety of industries with important uses for aerospace. Materials used for SPF are mainly titanium alloys which are good candidates to produce lightweight complex-shaped components for high performance applications. This process is particularly suitable for complex near net-shape forming, avoiding assemblies and decreasing the machining costs. Nevertheless, this process has limitations because it involves a high-temperature furnace with a current poor heat efficiency (5% with hot platen technology) and expensive tooling with low management flexibility. Enhancing this manufacturing process is a major challenge for the aerospace industry which is facing to important production ramp-up and cost reduction for the future. Direct heating by radiations combined with tool heat management result in significant savings of SPF process: production time savings by drastically reduce the heating time, reduction of maintenance cost and energy savings by significant increase of the heat efficiency.

Aurock developed direct heating by Infrared bulbs and succeed in forming series 1.5x1m² Ti6Al-4V blanks with a total control of the forming parameters. All these parameters are strongly dependent on the process temperature and a key point with this new technology is to obtain and ensure a homogeneous temperature of the blank all along the forming cycle. This point is achieved thanks to lamp power modulations during the cycle and by numerical techniques to secure the thermal regulation of the blank with a full control of the radiative flux needed at different stage of the forming. Results obtained on the formed parts were stable and repeatable regarding to complete forming and dimensional criterion as well as post-forming thickness distribution. Furthermore, microstructure is not affected by the quick and direct heating. Numerical thermo-mechanical predictions are in very good agreement to the experimental results and enable robust machine setup for series Infrared SPF parts production.