Differential Probe
A differential probe is an eddy current probe with two oppositely wound coils that suppresses homogeneous material influences and mainly reacts to abrupt inhomogeneities like cracks.
Physical-Chemical Mechanism of Action
The differential probe uses two windings with opposing current flow. This eliminates homogeneous signals coming from consistent materials and amplifies the response to sudden changes like cracks or damage.
Metallurgical Relevance & Risks in Welding
The differential probe is especially useful for detecting cracks or other inhomogeneities in the weld. A missing or defective measuring device can lead to inaccurate results, increasing the risk of undetected flaws.
Workshop Practice & Instructions
Use the differential probe to check the weld. Make sure both windings are correctly installed and calibrated. The measurement should be done directly after welding, before the workpiece cools down.