TWI Frequently asked questions
by Ivan Pinson
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:
The disadvantages are:
a)
b)
c)
d) | Less attenuation of sound energy
No probe ringing
No dead zone on the screen
The orientation of a defect does not matter in the way that it does on the pulse echo display. |
a)
b)
c)
d)
e)
f) | The defect cannot be located
The defect cannot be identified
The component surfaces must be parallel
Vertical defects do not show
The process must be automated
There must be access to both sides of the component. |
