Advances in Monitoring Die Condition during Superplastic Forming

Abstract

Superplastic forming of titanium is typically restricted to low volume, high value products due to the high costs inherent in the current process. Problems contributing to the high costs stem from the interactions that take place at the die/part interface and include; poor part surface finish due to the build-up of corrosion products on the die surface and part distortion due to adhesion at the die surface. This paper describes novel methods for the investigation of the build-up of corrosion products on the die using surface digitization tools with laboratory based simulations of the forming conditions and a novel method for monitoring, analyzing and quantifying the die surface condition in a production environment using a combination of thermal imaging techniques and image analysis.

Thermal Sprayed Protective Coatings for Superplastic Forming Ceramic Dies: A Monitoring System of Die Condition

“…In a previous work carried at the AFRC [11] it was developed a test procedure to study the interaction between an heat-resistant steel die and a Ti6Al4V part. A set of conditions was developed to be broadly representative of the SPF forming cycle.…”

“…In the recent years an outstanding effort have been made by the AFRC team in order to achieve a systematic method to analyse and monitor the die lifetime through the analysis of the scale built-up on the titanium parts after the SPF process [11]. After each run a scale arises on the titanium parts, because of different variables that have place during the SPF process: at those conditions several physical and chemical interactions happens between the die and titanium part interface.…”

“…The bottom stack introduces the static load that simulates the gas pressure in the SPF chamber. The top stack is linked to a rotation motor that simulates the sliding of part onto the die surface during the SPF process [11].…”

“…The ceramic die surface is analysed before and after the experiment, and compared with the Ti6Al4V surface scan from each production run to determinate the rate of die surface breakdown, as already implemented for the metallic dies [11].…”

“…Thermal imaging techniques have been adapted to monitor the die surface conditions during the manufacturing production cycle. A Land Instruments FTI-E 1000, 600-1000°C thermal imaging camera was installed within an SPF production facility to monitor the condition of the metallic die surface [11]. In the presented work, the same technique has been adapted to ceramic dies.…”