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magnaflux device

Discussion in 'General Electronics Discussion' started by Danlsimon52, Dec 20, 2012.

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  1. Danlsimon52


    Dec 20, 2012
    Hi all!

    I am a new poster, and I am trying to get an idea on how to...or even if it is possible to make a magnaflux device.

    This is used to check for cracks in automobile heads and blocks and other iron/steel parts.

    There are videos on utube showing them being used...and they look to be a relatively large u-shaped electromagnet. The ones in the video look like they are plugged in to an A.C. outlet (120?) but perhaps they could be D.C.

    They are put on the part to be checked for cracks and they induce a magnetic field apparently in the part (or localized section of the part) then iron filings are sprinkled onto the area being checked and if cracked the crack influences the magnetic field in a way that the filings "highlight" the crack.

    Automotive machine shops charge a lot for this...and the procedure looks simple enough if I can make my own device.

    Any suggestions would be greatly appreciated.

  2. quantumtangles


    Dec 19, 2012

    Electronic engineers with real knowhow will have more helpful suggestions than me...but absent any other responses to date, have you considered using one or other (or even a combination of) the following.

    1. Hall probe or Hall meter circuit (measures changes in magnetic flux)
    2. Other...metal detector circuit.

    For example (in the case of option 2,) with an electronic feedback signal from a specific pristine engine block, this could be assigned the value 'metal detected'.

    All values outside the subset 'metal detected' would indicate an anomaly potentially consistent with a cracked engine block.

    Sensitivity to fractures could be adjusted using a variable potentiometer.

    Fractures would therefore be anomalous (in terms of signal homogeneity) and flagged up to the operator by LED or tone generator.

    Knowing the value of the expected signal (for a good engine block) would be key. With a digital signature for an engine block 'X' in perfect condition, anything different would have to be deficient. Put more simply, a perfect engine block of density Y kg/m3 would register as 'metal detected'. Anything with lower density in terms of Kg/m3 (such as a cracked block) would be seen as 'metal not detected'. A binary solution.

    A simpler solution might involve measuring conductivity or resistivity in Ohms for a perfect engine block across a series of sensors (multimeters) placed around the engine block. A fractured engine block should have higher resistance across the fracture site. I saw a great circuit in Practical Electronics showing how to increase the sensitivity of Multimeters that might be useful and I will post it when the festive expectations of third parties have been satisfied (third party expectations = being prevented from learning anything for a few hours).

    A better solution would be an MRI machine for imaging tool way above my pay-grade.

    A mechanical engineer would approach this problem more directly. They would look for oil in the engine coolant, which could only have come from the engine block due to a cracked block, a warped block, or defective seals.

    Best of luck with it. Its a great project :D
    Last edited: Dec 25, 2012
  3. Danlsimon52


    Dec 20, 2012

    I appreciate your feedback.

    I was able to get online and find a catalog from Magnaflux (it is a company name as well) and they showed a D.C. rechargeable device.

    I am going to play around with a car battery, some decent gauge wire, and a bent u-shaped iron bar and see what I can jury-rig.

    My original concern was getting shocked using A.C. but hard to get hurt with 12 volt D.C.

    The device looks simple enough.

    As an aside I was able to determine that they now make a non-electrical "dye" product that seeks out, finds and highlights cracks as well.

    The dye product is about a hundred since I am pinching pennies I will probably try to jury rig a 12 volt electric magnaflux device anyway.
  4. duke37


    Jan 9, 2011
    I would think that you could make a magnetic from U shaped transformer laminations. The bigger the device the more power will be needed. I think that DC would be better than AC. Where would you get your filings from.

    Dye penetrant.
    You could try red ink, possibly with some added alcohol (if you can spare it) to reduce the surface tension. This may not work if there is oil in the crack. Put the penetrant on the surface, let it sink in then wash it off and dust with fine powder (icing sugar?), as the dye creeps out of the crack a red line should be seen.

    Surface condition is a factor to be considered. It is difficult to see a crack if the component has a rough cast finish.
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