The German precision casting expert TITAL, based in Bestwig, Germany, has engaged in a partnership with the Institute ACCESS of RWTH, Aachen and other industry partners on a research collaboration. The goal being to dovetail scientific knowledge and practice and develop an efficient casting process for the engine parts made out of inter metallic alloy Gamma TiAl. Gamma TiAl is lightweight, heat resistant and perfectly suitable for usage in aeroplane engines.
The project is supported by the economic ministry of the state of NRW with €2.5 million. The company TITAL and other industry partners are also contributing to the collaboration with their own funds. The outcome of this being one of the most ambitious engine- technology projects worldwide being located in NRW.
Gamma TiAl is an inter-metallic alloy of Aluminium and Titanium. This alloy has existed for almost the past 30 years, which the industry manufactures as before, but still faces some challenges. The main problem with the processing of Gamma TiAl, explains Hans-Peter Nicolai, the project co-ordinator from TITAL, is that “the alloy cannot be machined, turned or bored into, neither can it be melted properly”. The only option therefore left for the processing of Gamma TiAl, from an economic perspective, is the process of casting. Even here there are many complex technical difficulties which have to be overcome.
Mr Nicolai said: “Through the whole process of casting and cooling the melt until the final prefabricated parts are formed, the Gamma TiAl alloy must be controlled, for which there is no current methodology and which if not done could cause internal structural damage making the parts unusable.”
Due to Gamma TiAl’s extreme lightweight and heat resistant qualities it is most suitable for engine design. A solution for processing Gamma TiAl has therefore long been sought after.
TITAL managing director Philipp Schack said: “We would therefore like to cooperate with ACCESS in developing a methodology, by which the casting process can be made easy and inexpensive and can be used for engine production.”
Gamma TiAl has a density of 4g/cm³ and is 10% lighter than the already available light Titanium alloys. It is only half as heavy as comparative special steel alloys and can withstand temperatures of up to 850°C. Normally Titanium alloys can only resist up to 600°C.
Mr Nicolai said: “In the aircraft engine, masses rotate with up to 5000 rpm. With help from light Gamma TiAl parts, the forces can be reduced significantly. In aircraft engine manufacturing, importance is given to minimum weight required to withstand force and not designed for optical appearance.”
ACCESS has been developing and optimising metallic components and castings since 1986. It has been successful in casting small, low-pressure engine blades out of Gamma TiAl. Now this methodology should be tried out for bigger vanes which measure up to 285mm in outer width length. These vanes have tremendous technical potential.
TITAL managing director Philipp Schack said: “If we are able to realise our intent, then we can position this as a unique technological alternative in engine technology in the global marketplace.” The aerospace engine industry, with Rolls Royce as the leading European player, is today already the most important consumer of Titanium castings. The Titanium castings market is currently dominated by two American suppliers.
After successful development in the project, ACCESS and TITAL hope that, with this support from the state government, it will be possible to compete globally. In a nutshell, Mr Schack evaluates the project as very positive. “The material Gamma-TiAl has great potential in the future – assuming we are able to find a way to produce it at a competitive cost. The project costs a lot of money but it is important to note that the industry is requesting support for a very promising project. When we are successful in this collaborative venture, then the industry would payback many times over the investment that the state government has made.”