Mag NDT
Non-destructive testing using magnetic sensing, reading through material rather than around it.
The problem
What this capability is
Inspection usually means either taking something apart or accepting that you cannot see inside it. Magnetic non-destructive testing is the third option: read the field around a part and infer the state of the material from the way that field is disturbed.
Mag NDT works because a flaw is a discontinuity, and a discontinuity in a ferrous material shows up as a local distortion in the field passing through it. Corrosion thinning a wall, a crack under a weld, a void inside a casting — each perturbs the field in a way that is measurable from outside, without contact and without removing the part from service.
The limit has always been sensitivity against size. A sensor good enough to resolve a small defect has been large, power-hungry and awkward to array. A chip-scale atomic magnetometer is small enough to array, which turns inspection from a single-point measurement into an image, and changes the economics of inspecting things that are long, numerous or hard to reach.
Applications
Example applications
Applications are examples of what the capability enables, not products.
- Pipeline inspection
- Wall loss and weld condition read from outside the line, without taking it out of service.
- Electronics manufacturing
- Current paths and buried defects in assembled boards, read without contact.
- Automotive and aerospace parts manufacturing
- Verification of critical parts as they are made, rather than by sampling them afterwards.