Overview
High market demand for gas turbines in the aircraft industry has driven the need for more efficient, reliable and flexible manufacturing technologies for the production of turbine components.
The ADMAP-GAS project strives for the production of gas turbine components that are efficient, cheap and environmentally safe. The project aims to achieve low tool manufacturing costs, low maintenance costs, continuous production processes, flexible and fast change in production lines, requirement of less machining space and easy correcting of process inaccuracies.
In the project new Unconventional Advanced Manufacturing Processes for Gas-Engine Turbine Components will be developed in order to substitute the critical conventional broaching process for fir tree profiles between rotating blades and disks.
The project will evaluate Water Jet Cutting and High Speed Wire Electro Discharge Machining ("High Speed Wire-EDM") as alternatives to broaching, a machining operation known to experience problems with high tool wear resulting in high maintenance costs, disruption of the production process and inflexibility with regard to changes in the work piece geometry.
The High Speed Wire-EDM Broaching and Abrasive Water Jet Broaching techniques will be further developed, optimised and their individual performance and effectiveness for the machining task will be evaluated. High material removal rates and highest surface finishing will be achieved, resulting in an equal or even better work piece performance. By using these two unconventional manufacturing technologies, with their inherent advantages, a much higher technological and time based flexibility in production of fir tree profiles can be achieved. Failure risks and machining costs will be drastically decreased due to faster and more efficient machining in combination with a higher degree of automation. Tool wear and time consuming tool renewal can be avoided. Machine tool footprints (in comparison to conventional horizontal broaching centres) or machine heights and fundaments (vertical centres) will be drastically reduced. Energy consumption will be reduced and environment will be preserved.
Funding
Results
During this project, both processes will be evaluated regarding their performance in the production of the fir tree geometry. The technologies of the Water Jet Machining and High Speed Wire-EDM will permit an efficient manufacturing of fir tree profiles in super alloys. High material removal rates in combination with a high form accuracy and surface quality can be achieved. Both processes allow a very flexible production of different profile geometries. No special tool has to be manufactured. The wear has no influence on the workpiece performance. Generally, less machining space and fundamentals are required.
Innovation aspects
The use of broaching as a manufacturing process is the most widely used technology to bring complex internal or external profiles, such as fir tree profiles, into the components. However problems inherent with the broaching process has forced the need to consider alternative technologies.
When material or technical limitations do not allow the manufacture of fir tree geometries on turbine disks for the gas turbine and aerospace industries with “near-net-shape” casting or forging, the use of broaching as manufacturing process, is the most widely used technology to bring such complex internal or external profiles into the components.
High surface integrity and accuracy requirements are demanded. The condition of broaching tools has a significant influence on achieving the level of surface integrity required in aerospace industry, particularly the rotating parts of the aero-engines. However, excessive broaching has been directed to produce several types of workpiece surface anomalies as follows: directed scoring, smearing of parent material, surface overheating and plastic deformation.
Usually, the method adopted by aero engine manufacturers is to “freeze” the process following process qualification to first article inspection, and successful part validation via laboratory examination and testing. Once frozen, no changes to process parameters are permitted without re-validation.
Regarding the working conditions, the common broaching speed is very small for roughing and finishing operations (around 3 m/min) when the machines can work up to 60 m/min. The increase of cutting speed can lead to a damage in the surface workpiece which forces to limiting the maximum cutting speed above all in the in the finishing stroke.
All this leads to several disadvantages of broaching which will be eliminated in the project. They are the following:
- Surface anomalies
- Inflexible regarding change in process and process geometry
- High tool manufacturing costs
- High tool wear leading to high maintenance costs
- Discontinuous process because of time consuming regrinding
- High machining space required
- No reworking during the process possible.
The two new and promising alternative processes considered as substitutes to the critical broaching process during manufacturing of fir tree profiles on blades and disks are:
- High Speed Wire-EDM
- Water Jet Machining.
Strategy targets
2. Innovating for the future: technology and behaviour: 1.1 A European Transport Research and Innovation Policy