The RAPOLAC international research project has successfully brought a new manufacturing technique fofor the aerospace industry to the brink of commercialisation.

Eight academic and industrial partners from four countries collaborated on RAPOLAC (Rapid Production of Large Aerospace Components). The three-year project has developed the shaped metal deposition (SMD) process from an experimental proof of concept, to an automated manufacturing technology ready for use by a range of companies. The University of Sheffield Advanced Manufacturing Research Centre with Boeing (AMRC) was lead partner.

SMD produces components by welding a continuous metal wire into the desired shape. This reduces the wastage involved in machining parts from a larger block, and removes the need for the expensive tooling used in forging. Using SMD, the time required to design and produce a large aerospace component such as an engine casing can be reduced from nine months to a few weeks.

The SMD technology was initially developed by Rolls-Royce plc, but was not widely adopted for commercial production for several reasons. The TIG welding process had to be manually controlled by a skilled technician, and there was little understanding of the material properties of the parts produced by such an innovative process.

Rolls-Royce licenced the technology to the AMRC to move SMD towards commercialisation.

Rosemary Gault, RAPOLAC project manager, says:
"SMD was a very promising technology when it came to us, but companies weren't interested because it was very labour intensive and we didn't understand the material properties. Thanks to the funding from the EU Framework Programme and the hard work of all our partners, it's now been fully modelled and automated. It's ready to go into wider production, and we're talking to a number of companies from aerospace and other sectors."

Researchers at the AMRC focused on optimising the SMD process, ensuring that parts are produced with the best achievable material properties in the most efficient way.

The researchers proved the empirical relationships between weld parameters (such as travel speed, wire speed and welding current) and the material outputs (including bead thickness, shrinkage and hardness). This knowledge was then used to develop a stable parameter window with known mechanical properties for the desired part size.

Gustavo Escobar of the AMRC says:
"We now understand how the key process factors affect the system's outputs. We are able to predict part geometry and customise the microstructure of parts to achieve the required mechanical properties. Industries using SMD will benefit from a well-understood process where parts are produced right first time, to very high standards."

For full details, see the RAPOLAC press release.