F-GRIP – an innovative approach to blade manufacturing

The production of blades involves certain challenges in the manufacturing process: For machining of the root and shroud area of blades, in many cases clamping of the parts can only be done after a well-defined encapsulation of the complexly shaped airfoil into a block of low-melting alloy. The block can be used for clamping purposes during machining and has to be removed by melting afterwards. This encapsulation process cannot be considered to be a green process, in addition to lead time and costs.

The challenge

For German company Leistritz Turbinentechnik GmbH, which is a partner to all aerospace OEMs, is ensuring the high performance of their blades in aero engines, of utmost importance.

Enhancing the blade manufacturing process with F-GRIP seems to be a very progressive alternative to conventional clamping and machining”, says Dr. Marianne Baumgärtner, Director R&D at Leistritz. “That is why we wanted to put it to a harsh test.”

In October 2019, Fresmak performed in a planned iteration the 3rd F-GRIP demonstration test for Leistritz. The test campaign was performed in the facilities of ACCESS e. V., a technological center and long term partner of Leistritz in developing materials and manufacturing processes.

For this demonstration of effectiveness, we challenged Fresmak to clamp an airfoil of an aircraft engine on the casted convex side of the airfoil made of Titanium Aluminide”, says Hans-Christian Melzer, Director Business Development. Titanium Aluminide is an intermetallic material that has very similar mechanical properties to Nickel casting alloy, but only half the weight.

The positive result

Fresmak designed a robust fixture for clamping the part for the machining of the root and shroud using 5-axis milling technology. The machining tests were conducted under representative production conditions with no discount to machining forces, tool speed and feed rates compared to a massive clamping and serial conditions. The trials comprised 15 pieces which have been fully dimensionally inspected.

For Leistritz the test run was a great success as it confirms the possibility to clamp parts by adhesion using moderately curved surfaces, thus opening new applications.

“For us these results open up new options to clamp parts in sensitive areas and machine those parts with higher efficiency resulting in greater competitiveness.”

Fresmak gratefully thanks Leistritz Turbinentechnik GmbH and ACCESS e. V. for their support and collaboration from the first investigations until the final machining tests.