5-Axis Machining of Gas Turbine Blades for Power Generation

Turbine production is attracting considerable attention as the power generation sector experiences increasing demand for gas turbines. The high precision LX 251 5-axis machining center from Starrag USA Inc. (Hebron, KY) is designed for efficient, complete five-axis machining of complex, high-tech turbine blades in one clamping. It has a 58.9 in (1,495 mm) maximum distance between centers and 15.7 in (400 mm) swing diameter. Stroke on the X-axis is 63 in (1,600 mm), Y-axis 15.7 in (400 mm), and Z-axis 15.7 in (400 mm). The patented LX axis design forms the basis for a balanced distribution of masses. Independent control of the tip and root stations presents completely new possibilities in blade manufacturing. Both the A-Axis (root station) and AA-Axis (tip station) have 360 deg endless stroke and the Swivel B-axis has a ± 87 deg stroke. Axis feeds and rapid traverse on the linear X-Y-Z axes is 2.4 ipm, with 200 rpm on the rotary A-axis and 60 rpm on the rotary B-axis. The main drive spindle motor generates 37.6 hp at 100 percent duty, 133.5 lb-ft of torque at 100 percent duty and 18,000 rpm.

The thermal stability of the symmetrical mono-block polymer concrete machine bed provides optimal damping of components, low vibration and stable machining. All base frame components are designed using FEM analysis for maximum rigidity. Superb static and dynamic properties allow very high feed rates. The rigid machine bed, coupled with the high natural frequency of the base components, guarantees excellent stability, even during the heaviest machining. The symmetrical drive power, regardless of workpiece dimensions, has a superior effect on tool life. A versatile, modular and combinable clamping system, with torque compensation during the machining process, fulfils the most demanding manufacturing requirements. This machine guarantees consistent reproducibility of workpieces, which is critical when manufacturing fan blades. Specially developed measuring cycles for workpieces and tools guarantee consistent precision, and temperature compensates for areas with excessive heat build-up.

The easy-to-operate Siemens 840D CNC control provides a simple call-up of customer-defined machine parameter sets for optimal milling processes that enable dynamic 5-axis machining of free form surfaces or geometries. The Compression function controls any jumps in acceleration during transition from one line block to another.

Starrag USA Inc., Skyport Business Park, 2379 Progress Drive, Hebron, KY 41048, 859-534-5201, Fax: 859-534-5201, www.starrag.com.