ECA Surface Crack Detection

Evident Industrial Resources

Application Notes

Evident propels eddy current technology into uncharted territory in the aerospace industry, with an innovative surface crack detection solution for lap-splice inspection. The structure of an aircraft contains thousands of fasteners, so ensuring their integrity can be an arduous process. Conventional inspection techniques are typically very time consuming and the probability of detection is highly dependant on operator skill. Nevertheless, for over a decade the technology has remained relatively stagnant ... until now.

Using eddy current array considerably reduces the duration of an inspection, and detection probability is increased. This solution not only saves man-hours, but its streamlined inspection process helps minimize the possibility for error.

High Resolution Scan

The recommended ECA probe, the SBBR-026-300-032, is 26 mm (1 in.) wide and features 32 coils arranged in two rows. This configuration provides increased resolution and clear imagery, which is suitable for very high resolution scans. Its small coils (1.6 mm diameter) and high frequency (80–1000 kHz) allows operators to detect very minute cracks. It can also be used to scan through thin coatings, including standard paint thicknesses. Crack orientation is irrelevant for this probe, as its detection is omnidirectional. Scanning is also effective over ferromagnetic fasteners.

SBBR026-ENC probe kit

Scan Through Thick Coating

Another probe is available that can scan fasteners through thick non-conductive coating: the SEB-064-005-032. Though it does not provide high resolution like the SBBR-026-300-032, its low-frequency range (0.5–50 kHz) and bigger coils can scan through thicker, nonconductive coatings like paint, stickers, and rubber. Due to its large coverage (64 mm), two rows of fasteners can be scanned at one time. And, cracks do not have to be oriented in a specific direction, as this probe is also omnidirectional.

Intuitive imagery

Sample with EDM notch

C-Scan

Performance for different notch lengths

Omnidirectional detection

No coating

2.5 mm of nonconductive coating

SEB064-ENC probe kit

Products Used for This Application

OmniScan MX ECA/ECT

Performs eddy current array testing inspections. The test configuration supports 32 sensor coils (up to 64 with an external multiplexer) working in bridge or transmit-receive mode. The operating frequency ranges from 20 Hz to 6 MHz with the option of using multiple frequencies in the same acquisition.