Time-of-Flight Diffraction Technique
Time-of-flight diffraction technique is an acoustic testing method that evaluates the diffraction of ultrasonic waves at crack edges and tips to precisely measure the vertical extent.
Physical-Chemical Mechanism of Action
TOFD uses ultrasonic waves reflected at crack edges and tips. The time it takes for the sound to travel from one point to another (Time of Flight) is measured and analyzed. This measurement allows you to determine the exact position and size of the crack.
Metallurgical Relevance & Welding Risks
This technique is especially useful for checking weld quality because it detects microscopic cracks or flaws. A crack that's too big can weaken the part and lead to failure. So precise measurement is critical for the safety and reliability of the part.
Shop Practice & Action Steps
To use TOFD, you need an ultrasonic unit with special software. You send the sound waves into the part and measure the reflections. The time of flight of the waves is measured in microseconds and interpreted with the software. It's important that the unit is properly calibrated and that measurements are done under controlled conditions.