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Unconventional (Advanced) Manufacturing Processes for Gas-engine turbine components

Tags: Air

State of the Art - Background

Due to a high increase in market demand for gas turbines in the aircraft industry, efficient manufacturing processes for turbine components are necessary. The need for individual and adapted product solutions calls for efficient, reliable and additional flexible manufacturing technologies. Today, the high temperature nickel/titanium alloy gas turbine rotors are produced by assembling disks and blades. Fir tree profiles connect both elements, resulting in a closed-form and space-saving assembly of the parts.

Broaching fir tree profiles is a very critical process during the manufacture of gas turbine parts. Although very high metal-removal rates in combination with high surface qualities and accuracies can be achieved, the broaching process wears tools, resulting in additional high maintenance costs. The time-consuming regrinding operations of the broaching tools also prevent continuous production. Furthermore, the broaching process is very inflexible regarding a change in the work-piece geometry.

New and promising alternative processes would be able to substitute this critical broaching process.


The objective is to substitute the critical broaching process of fir tree structures in gas turbine blades and disks by the alternative processes of Water Jet Cutting (WJC) and High Speed Wire Electro Discharge Machining (High Speed Wire-EDM).

New developments and adaptations in generator technology and process control will allow a much higher cutting rate during Wire-EDM in combination with an almost damage-free rim zone. This High Speed Wire-EDM and Abrasive Water Jet Machining (AWJM) process will economically produce fir tree profiles for blades and disks in titanium- and nickel-based super alloys. These characteristics result in lower production costs and higher process reliability.

With proper data management that will be developed during this project, the machines can be programmed for different geometries by taking advantage of their CNC flexibility, using knowledge-based manufacturing technologies in which the properties of both processes can be used for the efficient, cheaper and environmentally safe production of gas turbine components.

The advantages of these investigations will be:

- lower tool manufacturing costs;

- lower maintenance costs due to less tool wear;

- a continuous production process;

- flexibility and efficiency when the work-piece geometry has to be changed;

- less machining space required;

- easily corrected process inaccuracies.

Description of Work

There are three main technical work packages (WP).

WP1 is mainly focused on the development of the Wire-EDM process to prove that it is able to produce fir tree structures with high profitability and precision. A faster cutting rate can be achieved with new generator technology, new wires, new dielectrics and flushing optimisation. This increased cutting rate will be tested for fir tree slotting and rough machining blisk structures. To generate a minimised heat-affected zone the process has to be run with low discharge energies. The used dielectric will also have an influence so different dielectrics and additives will be developed.

WP2 will focus on the water-jet machining process in order to evaluate the capability of substituting the broaching. This will be achieved through improved process control and tighter tolerances, via the development of new abrasives and carrier materials, and through a closed-loop control of the process allowing features and pockets to be created.

WP4 covers the development of the integrated process and data management system. Here the communication between different development steps will be realised in order to improve the efficiency of CAD/CAM data integration into the two main machining technologies described above.

Expected Results

The major deliverables of the project are:

- the development of modified machine tools and components, new wires, improved dielectrics and additives to optimise the process;

- the creation of new nozzles and machine set-ups and control algorithms for AWJM technologies;

- a comparison of AWJM with broaching and rough machining of blisks;

- an evaluation of both technologies and intelligent process combinations in comparison to existing process chains for manufacturing fire tree profiles;

- to test, demonstrate and verify the new integrated processes for manufacturing real gas engine components.

Concept of ADMAP-Gas
Concept of ADMAP-Gas

Comparison between broaching and Wire-EDM + Water Jet
Comparison between broaching and Wire-EDM + Water Jet