TABLE 2 - SUMMARY OF DIFFERENCES BETWEEN ACFM AND EDDY CURRENT
|
ACFM
|
EDDY CURRENTS
|
|
| Crack Depth Measurement without Calibration |
Yes
|
No
|
| Maximum Depth * |
about 30 mm
|
about 5 mm
|
| Crack Length Measurement |
Yes
|
Yes
|
| Crack Detection and Location |
Yes
|
Yes
|
| Signal Variations due to Lift-off |
Low (Bx only)
|
High
|
| Easy deployment in transition region (eg Weld) |
Yes
|
No
|
| Easy to automate probe scanning |
Yes
|
No
|
* N.B. Depth is the distance down a crack face from a metal surface to the crack tip - not the distance from the metal surface to a buried defect.
