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What are the advantages and disadvantages of the through transmission method of ultrasonic inspection?


Frequently Asked Questions

Through transmission was used in the early days of ultrasonic testing and is still used in plate and bar production.

A probe on one side of a component transmits (T) an ultrasonic pulse to a receptor (R) probe on the other side. The absence of a pulse coming to the receiver indicates a defect.


The advantages of through transmission are:

  1. Less attenuation of sound energy
  2. No probe ringing
  3. No dead zone on the screen
  4. The orientation of a defect does not matter in the way that it does on the pulse echo display.

The disadvantages are:

  1. The defect cannot be located
  2. The defect cannot be identified
  3. The component surfaces must be parallel
  4. Vertical defects do not show
  5. The process must be automated
  6. There must be access to both sides of the component. 

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