GOM Metrology

GOM Metrology

Inspection of nozzle guide vanes (NGVs)

Inspection of nozzle guide vanes (NGVs)

Efficient, high-throughput 3D inspection of NGVs

NGVs are critical for directing the flow of hot gas into the turbine blades. The angles, flow direction and throat area must be robust enough to ensure optimal aerodynamic performance, fuel efficiency and key engine characteristics as designed.

3D metrology systems from GOM can detect the tiniest flaws on the complex geometries and surfaces of an NGV. The digital twin can help optimize all processes, from design to MRO.

Design and composition

NGVs present engineers with daunting design challenges. These include the operational temperatures, the need for light-weight designs as well as optimal assembly conditions.  Each segment consists of multiple features, in addition to the airfoil. Engineers are constantly searching for new and innovative ways to optimize these issues.

Our solutions

3D metrology solutions from GOM, known as ATOS, can accurately measure and inspect the most complex NGV designs in a fast measurement time.

The ATOS portfolio comprises a wide range of 3D scanners and measuring machines. Coupled with our GOM Inspect evaluation software, sophisticated analyses of the part are possible.

Digital twins for more efficient engineering

Engineers must be able to identify every change along an NGVs’ life cycle. Even tiny deviations from the drawing can have far-reaching consequences for performance and safety.  Digital twins are extremely valuable tools for managing this.

Digital-twin technology has already transformed the aviation industry by drastically improving first-part quality.  ATOS technology creates a high-resolution digital twin from the 3D data of actual parts.  The 3D data can then be used throughout the NGVs’ lifecycle to help designers improve current and future products, for example by connecting the digital twin to other data sources in the background.

Benefits of digital twins for NGVs

  • Virtually assemble NGVs to simulate fit, form and function
  • Simulate how the NGV will perform in the real world over its lifetime
  • Use big-data models to predict performance characteristics
  • Track NGVs’ condition over lifetime
  • Predict lifetime of old and new designs
  • Increase collaboration between all stakeholders who are involved with NGVs 
  • Optimize machine processes


NGVs are typically made as single parts, pairs or triplets and linked to engine derivatives and to the complexity of the design and manufacturing process. Investment casting, machining and coating each present unique challenges, and also increase the risk of defects during production.

Improve your right first-time quality

From the casting to the finished machined part and coating, 3D metrology from GOM produces accurate, high-resolution scans of NGVs in a fast measurement time.  GOM Inspect software visualizes deviations between actual and nominal data regarding shape, position, trailing edge geometries, surface, thickness, edges, and much more.  In advanced use cases, our customers have analyzed the throat area, measured the coating thickness, and checked for the presence of cooling holes.

The 3D data will enable you to validate moulds and dies, analyze the performance of finished cast products and optimize your manufacturing processes. The result will be a dramatic improvement in right first-time quality.

Faster inspections

Our advanced ATOS 5 for Airfoil sensor has achieved a cycle time for NGVs of under 5 minutes for 48 measurement positions, with a repeatability of less than 0.004 mm. Depending on the requirements, a 4-minute cycle time is even possible.

A standard measurement using SmartTeach , an advanced functionality within GOM Inspect, will enable you to find the best compromise between the measurement speed that is allowed and the required quality level.

Benefits of GOM 3D metrology for the manufacturing of NGVs

  • Measurement and validation of moulds, dies and cast parts
  • Advanced airfoil and curve inspection
  • First-article inspection
  • Validation of machining processes
  • Nominal-actual comparison
  • Point-based inspection
  • GD&T analysis
  • Inspection of surface defects
  • Trend and deformation analysis
  • High-resolution digital twin
  • Measurement of throat area
  • Thickness of thermal barrier coating  
  • Presence of cooling holes

Throat area measurement

The throat area is the key characteristic for metering the gas flow through the entire gas turbine. Therefore, understanding this area and obtaining an accurate calculation of it is vital for performance and fuel efficiency.

ATOS 3D metrology can produce an extremely accurate view of the throat area thanks to the thousands of points that have been scanned. Engineers can then calculate individual sections, boundaries, and specific inspection points as needed even the orientation for the individual NGV's based on the throat area, all is possible with ATOS 3D metrology and ZEISS Quality Suite.

Furthermore, the digital twin of the NGV opens up endless design opportunities. Think of digitally assembling full rings of the NGVs to optimizing the order and even the orientation of individual NGVs based on the throat area, all of this is possible with ATOS 3D metrology and ZEISS Quality Suite.

Non-destructive inspection of thermal barrier coating

The application of the thermal barrier coating (TBC) is another key step in the NGV manufacturing process.  With ATOS technology, you can check the thickness of the ceramic TBC non-destructively by scanning the part before and after the coating has been applied. A high-resolution map of the entire coated surface provides immediate feedback with all measurements, including pass or fail against the pre-defined tolerances. The results can be used to adjust manual or robotic application processes in order to achieve the desired thickness and uniformity of surfaces.

This approach will drastically reduce your costs compared to the traditional methods of coating analysis, such as CMMs, non-destructive analysis with Eddy Current Testing (ECT), or destructive analysis with EDM and microscopy. It’s even possible to use GOM data to perform other activities like reopening cooling holes as part of MRO.


Maintenance, Repairs & Overhaul (MRO)

Because of their location in the engine, NGVs are constantly exposed to high temperatures. Even with the best cooling, these thermal stresses can, over time, cause defects. MRO service visits are therefore crucial events in the lifetime of an NGV.

That said, servicing and repairing NGVs is costly and complicated. The NGVs must be disassembled to check for wear or defects.  If an individual vane has to be replaced, the geometries of the new one must have the same geometries as the remaining vanes in the segment, which may have changed over time.

Our solutions for MRO

MRO shops are naturally interested in reducing the cost for their customers and maximizing the lifetime of the vanes. Optical non-contact 3D metrology from GOM is the answer.  Within minutes, ATOS technology produces detailed actual-nominal surface comparisons, form and position checks, and precise airfoil measurements.

The digital twins created from the 3D data can speed up the repair and maintenance process and improve your predictive maintenance.  ATOS technology therefore offers a significant cost advantage compared to traditional MRO techniques.

Advantages of ATOS technology for MRO of NGVs

  • Fast, autonomous scanning
  • Surface-defect map with characterization of defects
  • High-resolution, repeatable measurements
  • Intelligent airfoil software functionality
  • 2D /3D comparison and GD&T using PMI or drawing
  • Digital twin for efficient repair and condition tracking, as well as better predictive maintenance
  • Adjust throat area through simulation (assembly or fluid dynamics)

Metrology Systems

Thanks to our broad portfolio of 3D measurement machines, we can offer the right combination for every type of production and level of automation on your shop floor.

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