Application of Ultrasonic Thickness Measurement in Turbine Blades

01 Importance of Thickness Inspection

If the local thickness of a turbine blade is too thin, it may result in insufficient structural strength, potentially leading to cracks, fractures, and other serious failures during operation, directly threatening flight safety.

High-precision ultrasonic thickness gauges can detect micron-level thickness deviations, enabling early identification of such safety risks and ensuring that every blade meets structural strength requirements.

Thickness measurement also verifies whether the actual blade thickness matches the design specifications, preventing excessive aerodynamic resistance caused by over-thickness and ensuring that key engine performance parameters such as thrust and fuel efficiency meet design expectations.

02 Challenges in Turbine Blade Thickness Measurement

Irregular Geometry

Turbine blades contain different regions such as the blade root, airfoil section, and blade tip, while the blade body itself is usually designed with curved surfaces and varying thicknesses.

Ultrasonic waves are prone to refraction and reflection on curved surfaces, preventing them from traveling along the intended path to the measurement point, which may result in distorted measurement data.

Influence of Grain Structure

Single-crystal alloys and directionally solidified alloys feature coarse grains with highly oriented structures. Ultrasonic waves are easily scattered and attenuated at grain boundaries, leading to signal energy loss and weakened echoes.

Probe Coupling Difficulties

Ultrasonic measurement relies on couplant transmission between the probe and the blade surface. However, blade curvature and narrow spaces — especially near cooling channels — make stable probe coupling difficult. Variations in couplant layer thickness can introduce additional measurement errors.

Extremely High Accuracy Requirements

In the aerospace industry, turbine blade thickness measurement typically requires micron-level accuracy, significantly amplifying the influence of all potential error sources.

03 Instrument Selection and Measurement Solutions

Frequency Selection

Ultrasonic thickness gauges supporting 10–20 MHz frequencies are recommended to balance penetration capability and measurement accuracy.

Sampling Rate and Resolution

A system with a sampling rate of at least 100 MHz and thickness resolution of 1 μm should be selected to accurately capture weak reflected signal details and clearly distinguish echoes from the inner and outer blade walls, avoiding thickness calculation errors caused by insufficient signal sampling.

Specialized Probe Design

Customized small-diameter contact probes (φ1.5–3 mm) are recommended to reduce coupling influence when measuring curved blade surfaces.

Measurement Solution Demonstration

For this sample application, multiple solutions are available. One example is demonstrated below:

YUSHI PM10 Ultrasonic Thickness Measurement Workstation

Equipped with a 15 MHz pencil probe with a 2 mm contact diameter

500 MHz sampling frequency enabled

Additional Functions of the PM10 During Turbine Blade Measurement

When measuring turbine blades, the PM10 Ultrasonic Thickness Measurement Workstation also provides comprehensive and flexible interactive inspection functions.

Inspectors can import workpiece images and mark inspection points, enabling visualized workflow recording and management. All customized inspection settings can be saved as templates and imported into any PM10 thickness gauge, ensuring all inspectors follow the same inspection standards.

In addition, the PM10 supports a wide range of specialized probes, including:

20 MHz delay line probes

Spot weld probes

Contact probes

Water jet probes

Dual-element probes

Angle rod probes

These specialized probe options effectively solve many challenges associated with conventional probes and can be flexibly switched according to different blade inspection areas and testing scenarios.

Core Advantages of the PM10 Ultrasonic Thickness Measurement Workstation

The PM10 provides a professional, efficient, and reliable one-stop solution for turbine blade thickness measurement through the following key advantages:

Specialized probe adaptability

1 μm ultra-high resolution

Fully interactive touchscreen operating system

Full inspection data recording and traceability

Customizable inspection report templates

Portable integrated system design

These features effectively address the major technical challenges involved in turbine blade inspection.

Conclusion

High-precision thickness measurement of aero-engine turbine blades is a critical part of aerospace manufacturing quality control and in-service maintenance, directly affecting engine safety and operational reliability.

To address the measurement challenges caused by complex blade structures and advanced materials, properly selected ultrasonic thickness gauges and specialized probes can fully meet the stringent requirements of the aerospace industry.

This solution is suitable for both production quality verification and in-service blade maintenance inspections, providing reliable technical support for critical aerospace applications.

Please feel free to contact us for further discussion or technical support at any time.