Industrial CT Scanning for Microsurface Topography

Industrial Computed Tomography can be used for locating and measuring surface defects. Our client needed to measure defects across several batches of solenoid pins. However, the defects vary in size and location, and it can be particularly difficult to use a profilometer with such inconsistencies on curved surfaces. While the described measurements are not surface finish measurements because they lack the same algorithms and alignments, there is a strong correlation.

We used a profilometer for verification with using Rt (3 sample lengths, .8 cutoff) for an average of several measurements at 5.8 microns.

Thanks to one of our CT technicians, Bob McNamara, we have this high resolution photo showing a scratch from the demonstrated pin, as well as striations and other imperfections.

CT Data matches Profilometer Readings

The below images show the point density of the scan file and the profiling of the surface defects. The partial cylinder is comprised of nearly 119,000 points highlighted in red. The high to low deviations match the average measurement by our profilometer with a min/max range of .0055.

The deviation scale on the left images is +- 5 microns!