Manual ultrasonic testing (UT) is one of the more common non-destructive testing (NDT) techniques performed on materials. This testing utilises high frequency mechanical energy, i.e. high frequency sound waves to conduct examinations and measurements on a test area.
Typically, the UT inspection system consists of an ultrasonic transducer, pulser/receiver, and display unit. A pulser/receiver is an electronic device that can produce high voltage electrical pulses to the transducer. When driven by the pulser, the transducer generates high frequency ultrasonic sound energy into the material in the form of sound waves. These sound waves act as an ultrasonic flaw detector.
When there are discontinuities such as inclusions, porosity, cracks, etc. in the sound path, part of the mechanical energy is reflected from the discontinuities' (reflectors') surface. The reflected sound waves’ signal is received by the transducer and then transformed back into an electrical signal, whose intensity is shown on the display unit.
The time it takes for the reflected sound waves to return to the transducer can be directly related to the distance that the signal travelled, providing remote location information. The signal also provides information about other features, including reflector size, and orientation.
As an NDT inspection process, it doesn’t damage the parts being inspected.