CNC Grinding and Polishing of Large Turbine Blades
The MTS 6 CNC is a heavy-duty machine tool for grinding, polishing and finishing of aircraft engine fan blades, metallic leading edges, outlet guide vanes (OGVs), large steam turbine blades and industrial gas turbine blades.
6 interpolating CNC axis guarantee a perfect positioning of the contact wheel to the airfoil surface. An additional auto-adaptive pneumatic axis ensures constant grinding pressure. This allows the processing of complex blade and airfoil geometries and thus a reduction of milling processes and elimination of manual grinding operations.
. A powerful CAD/CAM software allows for fast and efficient generation of NC programs for any work piece geometry. The MTS is also used for finishing and polishing extrusion screws and crank shafts. IMM is the machinery supplier turbine OEMs trust.
Technical advantages of the MTS 6 CNC machine for turbine blade grinding and polishing
The MTS 6 CNC machine is designed for heavy-duty wet belt grinding, polishing and finishing of turbine blades and large airfoil components. Its six interpolating CNC axes combined with an individually programmable floating pressure axis ensure that the contact wheel remains perpendicular to the blade surface during machining.
This guarantees reproducible stock removal, excellent surface quality and high profile accuracy on large steam turbine blades, gas turbine blades, fan blades and metallic leading edges.
The rigid one-piece machine base enables stable machining of heavy workpieces while allowing overhead crane loading of large blades, buckets, screws and rotors. Programmable force-controlled CNC finishing ensures stable material removal even on large turbine blades.
Benefits of the MTS process:
- Consistent blade quality
- Excellent surface finish
- Repeatable material removal
- Easy CAD/CAM-based programming
- Reduced upstream milling effort
- Precise leading and trailing edge finishing
Grinding and polishing of a large steam turbine blade on the IMM MTS 6 CNC machine.
Why turbine blade manufacturers choose CNC for large blade applications
Unlike robotic polishing systems, the MTS is based on a rigid heavy-duty CNC machine tool concept with a fixed coordinate system and one-piece machine base.
This offers major advantages for large turbine blade production:
- stable positioning of heavy blades
- repeatable stock removal on large airfoils
- overhead crane loading of large workpieces
- high rigidity during wet belt grinding
- reliable standard CAD/CAM programming
- Siemens Sinumerik ONE control
For turbine OEM production this results in high repeatability, process stability and reduced manual correction effort.
Customers evaluating robotic finishing systems often choose CNC when fixed coordinate accuracy, process stability and repeatable material removal are essential for large turbine blade production.
The use of CNC belt grinding and polishing for turbine blades is well documented in aerospace manufacturing literature, including Aerospace Manufacturing Processes by Pradip K. Saha. This underlines the reliability and industrial relevance of CNC-based turbine blade finishing processes.
MTS 1800-800-6NC machine for grinding and polishing large steam turbine blades.
Materials processed on the MTS 6 CNC large blade grinding machine
Materials processed on the MTS 6 CNC large blade grinding machine
Materials processed on the MTS 6 CNC large blade grinding machine
The MTS 6 CNC machine processes a wide range of turbine materials used in power generation and aerospace:
- titanium alloys
- nickel-based alloys
- chromium steels
- stainless steels
- non-ferrous metals
The wet grinding process supports thermal stability and repeatable surface quality even on large blade geometries.
Surface quality improvement after upstream milling
Materials processed on the MTS 6 CNC large blade grinding machine
Materials processed on the MTS 6 CNC large blade grinding machine
The MTS process improves blade surface quality after milling and reduces manual finishing effort.
Typical improvements include:
- removal of milling marks
- improved roughness values
- reduced measuring effort
- optimized preparation before coating
Surface roughness levels achieved with the MTS 6 CNC process
Materials processed on the MTS 6 CNC large blade grinding machine
Typical surface roughness requirements in turbine blade manufacturing range from Ra 1.2 µm (≈ 47 µin) to Ra 0.6 µm (≈ 24 µin) for steam turbine blades, and from Ra 0.6 µm (≈ 24 µin) down to Ra 0.4 µm (≈ 16 µin) for gas turbine blades, guide vanes and aircraft engine blades.
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The MTS 6 CNC is designed for the automated grinding and finishing of large turbine blades and vanes with high repeatability and stable geometry control. Depending on the application, process setup and abrasive specification, surface finishes down to Ra 0.4 µm (≈ 16 µin) can be achieved directly on the machine, while finer downstream finishing steps can be supported where required.
For applications requiring higher surface quality, the MTS 6 CNC can be integrated into multi-step abrasive finishing processes. The same abrasive finishing processes are applied across different turbine blade sizes and geometries.
For turbine blades up to approx. 550 mm in length, the SPE 6 CNC turbine blade finishing machine is typically used, while the MTS 6 CNC is designed for larger turbine blade and airfoil geometries, ensuring stable processing of large-scale components. For a complete overview of turbine blade grinding, polishing and finishing processes, see our turbine blade production process (manual & CNC).
Such process integration helps reduce manual rework, improve process consistency and lower overall finishing effort in turbine blade production.
Siemens Sinumerik One control and CAD/CAM integration
The MTS 6 CNC uses Siemens Sinumerik One control and supports fast NC program creation through CAD/CAM software.
Advantages include:
- standard industrial CNC platform
- easy operator acceptance
- fast program generation from 3D data
- high repeatability in serial blade production
- optional adaptive processing based on measuring data
Customer benefits of the MTS 6 CNC turbine blade grinding machine
- constant blade quality across large turbine blade rows
- excellent and repeatable surface finish
- highly reproducible material removal
- reduced manual grinding effort
- easy programming through offline software
- savings in upstream 5-axis milling processes
- controlled polishing of leading and trailing edges
- coolant-based process for thermal protection and dust control
- proven machine concept for turbine OEM applications worldwide
Production benefits of CNC turbine blade finishing
- improved repeatability compared with manual polishing
- reduced measuring effort after polishing
- shorter milling cycles through balanced stock removal
- consistent blade quality across multiple rows
Programmable force-controlled CNC finishing for large turbine blades (H1, S, F)
In addition to conventional CNC parameters such as cutting speed (S) and feed rate (F), the MTS 6 CNC uses contact pressure (H1) as a fully programmable and continuously feedback-controlled process parameter.
This ensures constant and controlled contact pressure even on large and heavy turbine blades, enabling uniform material removal across long blade sections.
The system compensates for casting and forging tolerances while operating within a fixed and highly accurate machine coordinate system.
The result is a stable, quantifiable and repeatable finishing process with CNC-level precision — even for large turbine blade production.
Investment cast turbine blade post-processing on the MTS CNC machine
The MTS machine concept is used for post-processing of investment cast turbine blades and vanes in industrial gas turbine and aerospace production.
Material removal of more than 3 mm (0.12 in) is possible to remove casting deviations, correct blade profiles and prepare surfaces for final finishing operations.
The process supports nickel-based superalloys, titanium alloys and Ti-Al materials used in demanding aerospace and power generation applications.
Example applications: large turbine blade grinding and polishing on the MTS 6 CNC
Grinding of an investment cast industrial gas turbine blade on the MTS 6 CNC turbine blade polishing machine
Investment cast industrial gas turbine blade tip radius grinding with convex contact wheel on the MTS 6 CNC machine
MTS quick change contact wheel holders and tactile measuring probe. Available contact wheel diameters for blade polishing range from 35 mm to 200 mm.
Before and after example of aircraft engine fan blades polished and linished on the MTS machine tool.
Large steam turbine blades before and after polishing.
Polishing the leading edge of a large steam turbine blade.
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