Adaptive 5-axis machining of turbine blades

Citation

(2006), "Adaptive 5-axis machining of turbine blades", Aircraft Engineering and Aerospace Technology, Vol. 78 No. 5. https://doi.org/10.1108/aeat.2006.12778eab.004

Adaptive 5-axis machining of turbine blades

Adaptive 5-axis machining of turbine blades

Keywords: Aircraft components, Production engineering

Manufacture and repair of gas turbine components for aero engines and power generation is big business these days, with demand for air travel and electricity increasing year on year. One company that has taken advantage of the trend is Aylesbury-based TTL, which specialises in supplying fully interpolating five-axis cells and associated software for machining steel, nickel alloy and titanium blades. The company believes that it has a world lead by virtue of its adaptive machining software, which reportedly can engrave a raw egg shell without breaking it by first digitising its irregular surface. (Visit www.ttl-solutions.com for further information.)

The company's latest acquisition is a pair of Hermle gantry-type, five-axis, vertical machining (Plate 2) centres from Geo Kingsbury, one of which was configured with purpose-designed fixtures for reclaiming turbine blades before the cell was delivered as a working solution to an aero engine manufacturer in the UK. Similar turnkey systems are regularly delivered world-wide to third party MRO (maintenance repair overhaul) specialists, including the bigger airlines. The purpose of these machining cells is to eliminate expensive manual weld removal and blending when re-contouring compressor and turbine components, as well as to increase throughput, reduce turnaround times and improve accuracy.

Plate 2 TTL's Hermle C 30 U vertical machining centre is used for in-house development of adaptive, five-axis machining of turbine blades

TTL-configured machines for manufacturing new blades and vanes are also to be found in global markets, the company's exports having grown over seven years to account for 75 per cent of turnover.

The other machine involved in the latest order, a Hermle C 30 U (Plate 3), has been retained for in-house development at TTL. Commented Managing Director, Paul Walton, “Whilst our adaptive machining solutions can be provided on a wide range of machine tools, Hermle machines provide a robust, accurate and flexible configuration for many of our applications.”

Plate 3 Close-up of a typical blade milling application on the Hermle C 30 U

“They are also competitively priced and well sized for blade manufacture, having sufficient X-axis movement to accommodate fairly large components for land-based turbines while retaining the flexibility to machine much smaller aero engine blades.”

It was at the end of the 1990s that TTL bought its first Hermle machining centre in response to requests from customers in the plastic injection mould and formula one sectors for the production of complex 3D parts. Full five-axis machining was able to reduce cycle times and set-ups, and allowed features such as steep ribs and deep cavities in moulds to be milled rather than using time-consuming spark erosion techniques.

Having this facility on site provided the platform for TTL to develop its adaptive machining software for gas turbine component reclamation. The photographs show a typical blade milling application on the Hermle C 30 U. Each component is individually digitised and the resulting data is used to generate a unique toolpath for machining the blade back to its original profile.

The TTL host computer takes over executive control of the machine, using a low level communications interface with the Heidenhain iTNC 530 CMC system. This provides the facility for fully hands-free operation even on complex adaptive applications.

Details available from: Geo Kingsbury Machine Tools Limited, Tel: +44 (0) 23 9258 0371, Fax: +44 (0) 23 9250 1741, E-mail: mtools@qkholdinqs.com, Web site: www. qkholdinqs.com