Complete solution for the forging of turbine blades made of titanium aluminide
Leistritz Turbinentechnik GmbH ordered from Siempelkamp the design and supply of two 8 MN isothermal forging plants for the manufacture of turbine blades made of titanium aluminide. The customer will use these forging presses to manufacture a new generation of aircraft engines which are, compared to the nickel-base alloys currently used, up to 50% lighter while offering the same strength. Thus, they allow for significantly reduced fuel consumption.
Due to its intermetallic structure titanium aluminide is characterized by its high strength and excellent creep resistance at high temperatures. At the same time, at a density of 4 grams per cubic meter, it is very light. Therefore, it is ideally suited for aircraft engines. The material provides the potential to reduce the weight of turbine blades for aircraft engines by up to 50% which also goes along with a significant reduction of the centrifugal forces. The lighter design of the engines, made possible with the new components, will contribute decisively to reduced fuel consumption.
Intermetallic titanium aluminide was considered as not forgeable for a long time. Compared to casting, forging generates a special re-crystallization structure which is necessary for safety reasons for the rotating engine parts. In addition, the process stability during forging is higher than during casting and consequently, the turbine blades meet the extremely high quality requirements of the aircraft industry.
Leistritz has developed a new process where the blanks can be formed without cracks under carefully defined conditions at temperatures between 1,150 and 1,300 °C. The high forming temperature and the long dwell time of the forgings in the die, due to forming speeds of less than 0.1 mm/s, require heating the tools to forging temperature.
The extremely low press speeds require the hydraulic drive control to be especially accurate and uniform. Special guide and sealing systems assure uniform compression and thus avoid the undesired stick-slip effect. The symmetrical press design with a cross thread guide located on the outside allows for high precision forging. Because the guide elements are isolated from the heat source there is no thermal influence on the guide. The large distance between the guidance elements and the high rigidity of the press frame also contribute to precisely opposite aligned upper and lower dies during the forging process.
Leistritz has been operating a Siempelkamp 50 MN isothermal forging press since 1984. Due to the positive experiences and Siempelkamp’s expertise in the technologically sophisticated isothermal forging process, Leistritz contacted Siempelkamp early on and discussed different concepts. During pilot production, engineering talks about the design of the later production line started. In the beginning of 2014 both companies cooperated to develop the requirement profile for the plant allowing series operation. In November 2014 Leistritz commissioned Siempelkamp with the development and production of two manufacturing plants for the series production of turbine blades. Since the molybdenum contained inside the dies sublimates in the open air at temperatures over 600 °C oxygen has to be prevented from entering the dies. Therefore, the entire plant is enclosed which allows the complete automatic process, starting with the inserting of the blank at room temperature to the unloading of the forged turbine blades, to take place in an inert gas atmosphere.
Siempelkamp supplies both presses from a single source. The scope of supply for both presses includes a rotary hearth furnace, a loading manipulator, the forging press, the tool heating system, the hydraulic drive system and the complete electrical system. The process control monitors and documents the process parameters according to the certification standards in the aircraft industry.
The first press will start series production in March 2016, the second press one year later.
During several decades, Siempelkamp has accumulated vast experience in engineering and manufacturing metal forming presses. These include sheet metal forming presses for the production of large pipes and half shells, straightening presses, presses for the production of side members, presses for heat exchanger plates, hydroforming presses, presses for the production of rear axle housing as well as the full line of closed and open-die forging presses. The company specializes in customized presses with high press forces.
With the three business areas Machinery and Plant Manufacturing, Foundry and Nuclear Technology, the Siempelkamp Group is a leading technology provider with international scope.
The company enjoys worldwide reputation as systems supplier of presses and press lines for the metals industry as well as turn-key plants for the wood-working industry.
Siempelkamp Maschinen- und Anlagenbau GmbH
47803 Krefeld / Germany