Very nicely done! =Kudos to the voice-over actor, she pronounced everything correctly and gave the impression she was a true expert in the field. much to think about. The animation was excellent!!
Very informative, thank you. We use Eddy Current probes to measure the diameter of steel pipe, up to 2.375”, but I wasn’t very sure how it all worked. The pipe is moving at 150ft per minute while being inspected. There are also fixed magnets, magnetising the pipe longitudinally, and MFL sensors for transverse flaw detection, in the inspection head.
Excellent video! I really appreciate the superb combination of theoretical animations, alongside laboratory demonstrations. I wish my physics classes were taught half as well as this!
Thanks for yet another informative video! I regularly machine EDM notches in calibration blocks for non destructive testing. It's nice to finally understand how eddy current testing works! Danke für das schöne Video - Grüße aus Holland!
I have never seen this version of eddy current, I use the eddy current unit and probes. Very interesting to see another way eddy current can be described but it is confusing to me because it is brand new way of learning this familiar NDI/NDT technique. Thanks for posting.
Answer to "at 01:10, don’t forget that applying an alternating voltage is what creates an alternating current which will create an alternating magnetic field.": Perfectly explained, thanks!
It would be nice if you come up with the application part of this testing procedure, like measuring the thickness of the coating,evaluating heat treatment etc
Answer to "It would be nice if you come up with the application part of this testing procedure, like measuring the thickness of the coating,evaluating heat treatment etc": Thanks for pointing out further (important) applications - it is simply too much for us for the time being.
Geee, this is a supercalifragilisticexpialidocious video and i have relearned the eddy current thickness mearsurement. is the eddy current thickness gap signal linear on steel? thanks...:)
If the crack is smaller than the reciever coil would the lateral position of the crack inside the reciever coil mean more current drop than if the crack were in the center of the reciever coil?
Answer to "If the crack is smaller than the reciever coil would the lateral position of the crack inside the reciever coil mean more current drop than if the crack were in the center of the reciever coil?": This is an important point. A crack that does not affect the eddy current path cannot be detected, regardless of the coil arrangement. Thus, cracks that are completely outside the eddy current path, completely inside the eddy current path, or exactly parallel to the eddy current lines cannot be detected. However, if the eddy current path is affected by the crack, the arrangement of the exciting and receiving coils plays an important role. So the answer to your question could be yes or no. Unfortunately, this is a complex issue.
Answer to "What is the frequency of the alternative current that the coil needs in these experiments?" The alternating current frequency is around 10 to 15 kHz.
Dear Sir, why we are set hole on 40 degree and 1volt for differential channel and why we are set absolute channel 0.1 volt at 40 degree for internal tube inspection by bobbin probe. Can you please explain it
Answer to "For test what was the voltage used and how many turns does the coil have?" The voltage was 10 V, the number of the turns of the large coils was about 50 to 100.
MaterialsScience2000 Many thanks you can tell me what inductance of the coils that were used in the demonstration? Very good this video congratulations! !!
this content very awesome i'm trying to follow this video but i have a problem, when the coil contact to conductor nothing happen at my instrument can u help me
Answer to "this content very awesome i'm trying to follow this video but i have a problem, when the coil contact to conductor nothing happen at my instrument can u help me": Did you use about 10 V and 10 kHz frequency for the excitation coil? The devices must be able to measure voltages and currents with this frequency.
Why no voltage induced in receiver coil when there is no defect? there should be some voltage induced in receiver coil when there is no defect because if electromagnetic induction
Answer to "Why no voltage induced in receiver coil when there is no defect? there should be some voltage induced in receiver coil when there is no defect because if electromagnetic induction": But yes, a voltage is induced in the receiver coils. However, the induced voltage is different with and without a defect.
Answer to "Your video was so fantastic , i learn a lot from that , but i still can't understand about the coil. Can you tell me how to make the coil please": Thank you very much for the praise. As for the coils, they are very easy to make. You just take a lacquer insulated copper wire of about 0.2 mm diameter and wind it into a coil with about 20 to 100 turns. For very small diameters you don't need a bobbin, but for larger coil diameters you need a bobbin made of an electrical insulator; we used a transparent polymer material.
@@MaterialsScience2000 yesterday i practice make the eddy current test like that. But the current meter can't up when the coil entered the material test. I don't know what wrongs with that , can you tell me, maybe there are something which must be considered
"yesterday i practice make the eddy current test like that. But the current meter can't up when the coil entered the material test. I don't know what wrongs with that , can you tell me, maybe there are something which must be considered": We had similar difficulties at the beginning and had to change many parameters: the frequency, the voltmeter, the ammeter, the material. I'm afraid it's too long to explain in detail, sorry.
Answer to "If someone wants to replace or attach a bulb with the current meter, the bulb should be how many volts...... thanks": You could actually replace each of the measuring devices with light bulbs. However, this is not practical because, as you can see, the voltages are typically less than 1 V and the currents are much less than 100 mA. The voltage drop across the ammeter is very small, typically less than 100 mV.
Answer to "will eddy detect 0.1 mm hole in stainless steel tube of wall thickness 0.4 mm"? This is a real problem, but it should work under certain circumstances. It will not be possible to detect such a small hole with a large coil, as shown at the beginning of the video. But it should work with a very small coil, maybe an even smaller coil than the one shown towards the end of the video.
Answer to "Why did you stop uploading videos?" A fair question. Well, we've been pretty busy with other topics. But several new videos (about the tensile test, advanced level) are in the queue.
I have a question. If you get a copper tube, wrap copper wire around and hook it up to some output, and you drop a strong magnet through the tube, will the eddy currents turn on the output? Sorry if this question is kind of novice
Answer to "I have a question. If you get a copper tube, wrap copper wire around and hook it up to some output, and you drop a strong magnet through the tube, will the eddy currents turn on the output? Sorry if this question is kind of novice" Yes, you will be able to measure a short-time voltage at the ends of your copper wire in the form of a single +/- wave (as long as the magnet doesn't tumble around). The copper wire should be wound closely together in the form of a compact coil (not a very long one). Imagine the middle part of the tube. When the magnet drops through the tube, the local magnetic field changes rapidly and induces and eddy current in the tube. This eddy current creates its own magnetic field that superimposes with the magnetic field of the passing-by magnet. The resulting magnetic field (correctly: change of flux) flows through the coil made from copper wire and induces a voltage there. Actually quite complex; the falling magnet is slowed down more or less depending on the set up.
Answer to "why does the inductance become low when the core is added？shouldn't it be higher since u is higher.": It is because the eddy current inside the (intact) specimen (the ring, the core) is high. The high eddy current produces its own magnetic field which acts against the primary field. So altogether the excitation coil "feels" less inductivity and less counteracting voltage inside the excitation coil.
Answer to "I would like to know the wire diameter used, and the dimension of the core please": For video demonstration purposes the wire diameter was around 0.3 mm, the core diameter of the coil around 50 respectively 20 mm, the number of turns 50 - 100. These data are actually rather uncritical, the method works nicely with other data as well.
Answer to "nice video. can eddy current be used for subsea pipes?": Underwater inspection has its general difficulties. Nevertheless, eddy current inspection also works under water.
Since I'm currently studying for the Aviation Maintanence degree, would I have to buy my own Eddy Current Tester kit or would the workshop provide one?
Answer to "Since I'm currently studying for the Aviation Maintenance degree, would I have to buy my own Eddy Current Tester kit or would the workshop provide one?" For studying this degree, a "selfmade" solution within a project or something similar would be a reasonable option. But later in "real life" a professional EC Tester kit is much better.
Answer to "Can this be used for non symmetrical objects?": In principle yes, but it strongly depends on the individual geometry. It is possible if the eddy current is obstructed by a defect, and this can also work with non-symmetrical parts.
Answer to "What kind of coil is he using?" All the large coils in our laboratory are simple flat coils with about 50 to 100 windings made from insulated copper wire
Answer to "How I do the coil (how many turn, caliber, diameter)?": This is quite a common question. You find the answers in the discussions below, please have a look.
