ACFM in Detail

Array Probe Deployment

For array probes inspection is carried out in a similar manner to standard probes. Array probe movement is linear and parallel to the expected defects. The main differences are :

• Array probes usually contain position encoders, making the use of location markers redundant and simplifying defect sizing.
• The encoder normally controls the data collection interval so the probe can be paused during a scan if required.
• The encoder may be wheel-driven or optical but both require the probe to be in mechanised contact with the surface. Contact pressure should be light to avoid excessive probe wear.
• Array probes often have a second orthogonal current and extra sensors so that transverse defects can be detected and sized without additional scans.
• Array probes inspect a much wider band of material, but scan speeds are lower because of the need to switch through additional sensors. A typical array probe may inspect a band 50-100mm wide at a speed of 10-25mm/sec.
• After completing a scan the data remains on the screen for analysis. The main extra feature available with an array probe is the ability to display data in a colour contour plot of the area inspected.

Crack Detection / Introduction / ACFM in Detail / Array Probe Deployment    1 2 3 4 5 Next