Automated Ultrasonic Immersion Testing
Testing method where the component and the ultrasonic transducer are immersed in a water bath to ensure constant and non-contact acoustic coupling. It is mainly used for large-scale semi-finished products.
In ultrasonic testing, water is only the coupling agent so that the sound can travel from the probe into the part. Air in between would completely absorb the sound. So you have to make sure the water is clean and free of bubbles, otherwise you'll get false indications. The rest is purely a matter of setting on the device: if you place the probe correctly and set the sensitivity cleanly, you'll find even small flaws. But remember: what you see is only the reflection of the sound – you have to interpret the display correctly to know if there's really a flaw or just a geometric corner.