The challenge
The sleeves are used in demanding automotive applications. Delamination on the outer surface—where the metal structure bulges or detaches over a certain area—can lead to premature seal failure in the field. The defect manifests as a subtle surface elevation, on the order of tens to hundreds of micrometers.
Differences in height on reflective metals are barely visible with a standard 2D camera. Visual inspection was time-consuming and unreliable.
The solution
Vision Partners tested a setup in the Vision Lab in Drunen where the casing rotates on its axis while a Hikrobot 3D laser profiler continuously scans the surface's longitudinal position. The laser line projects perpendicularly to the cylinder axis and measures the height position of each point on the circumference at high frequency. Through rotation and successive profile measurements, the entire outer surface is captured as an unrolled 3D height map.
The system consists of:
- 3D laser profiler with a Z-axis resolution of 1.58–1.74 μm, a repeatability of 0.41 μm, and a scan speed of up to 23,900 profiles per second
- Rotating test setup where the sleeve rotates around its axis in a controlled manner during the scan
- 3D point cloud analysis that compares the unrolled surface with a reference profile; deviations above an adjustable threshold are marked as potential delamination
- Trigger input via hardware encoder for synchronization between rotation position and profile acquisition
The test setup confirmed that the 3D laser profiler clearly depicted the delamination as a raised relief pattern in the point cloud, while the surrounding smooth surface remained nearly flat.
The result
The 3D scans of the casing show delamination as a clearly visible elevation in the surface profile. The domed areas are well-defined from the background texture of the metal surface and can be automatically classified based on height and surface criteria. The sub-micron accuracy of the sensor makes it possible to detect even early stages of delamination before the defect is visible to the naked eye.
By rotating the sleeve during the measurement, the entire 360° surface is inspected in a single scan cycle — without blind spots. This makes the method directly integrable into a production environment where sleeves are already mounted on a rotating axis.
Want to learn more about 3D surface inspection or delamination detection? Get in touch.
Read our case study about delamination on stationary objects.
