Metrology Applications

X-ray CT can be used for:

• Dimensional analysis
• Nominal versus actual comparison analysis
• GD&T (Geometric dimensional and tolerancing) analysis
• Internal defect analysis

Notes in dimensional analysis techniques

Dimensional analysis of cast, machined, or 3D printed parts is an essential process of process control, failure analysis, and research and development. There are mainly three techniques to measure the dimensions of complicated shapes:

• Coordinate measuring machine (CMM) - Mechanical and tactile measurement
• Optical scanner - Optical measurement
• X‑ray Computed Tomography scanner (CT) - X‑ray absorption-based measurement

Each technique has its pros and cons. A CMM is considered the most accurate, but it can measure only selected points on a surface. An optical scanner can measure the entire surface but cannot see any internal structure. An X‑ray CT scanner can scan the entire volume, including the internal dimensions and defects, but the sample size is rather limited compared to the other two techniques.

All three techniques listed above, including X‑ray CT, can analyze parts dimensions, such as the size of parts, diameter of a hole or cylinder, etc. You can also define XYZ coordinate and apply full GD&T analysis to test tolerances of various measurements.

Learning resources

To learn more about metrology using X‑ray CT:

• X‑ray Computed Tomography for Materials & Life Sciences webinar series - Data Analysis
• X‑ray Computed Tomography for Materials & Life Sciences webinar series - Metrology
• Ask the Expert webinar series - Voxels to Mesh Data to Simulation - How to Use CT for Metrology and Simulations

To learn more about X‑ray micro-CT:

• What is micro-CT: Everything you need to know about micro-CT