Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

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(h) (i) Scan the test areas as required. Scanning should not be carried out within 3 meters of AC machinery. Scanning increments should not exceed the width of the test coil of an absolute probe. For shielded coils, the scan index should be determined experimentally to ensure that the entire area to be tested is covered but a scan index of half the coil diameter is usually satisfactory. Record the results and any other information required. During testing for extended periods of time, the sensitivity should be rechecked, and adjustments made if required, at approximately 30 minute intervals and at the completion of the testing (Some standards require more frequent checking). This standardization procedure should include battery condition checks and sensitivity checks. If an instrument is found to be out of standardization, all areas inspected since the previous standardization verification should be rechecked. In addition, the instrument should be re-standardized if any part of the system is replaced or if any control settings that could affect the calibration are changed. Charlie Chong/ Fion Zhang
4.1.3.5 <strong>Testing</strong> in-service welds in ferromagnetic materials Welds are normally not tested for weld quality by eddy current testing because of the limited depth of penetration of eddy current. This is especially so for ferromagnetic materials, because the permeability reduces the penetration. However, in-service welds are often tested for fatigue or corrosion-related cracks by eddy current testing in preference to magnetic particle testing because of its ability to detect cracks through much thicker paint coatings, and because it is faster and interpretation of the results is usually generally easier. Fatigue cracks can be reliably detected through thickness of up to 2 mm of paint by eddy current testing, whereas to obtain magnetic particle indications from even large cracks requires the paint to be less than 0.5 mm thick. Charlie Chong/ Fion Zhang
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Electromagnetic Testing - Eddy Curr
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http://igor113.livejournal.com/5121
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Charlie Chong/ Fion Zhang
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同桌的你 Charlie Chong/ Fion
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Fion Zhang at Shanghai 2014/Novembe
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5.0 APPLICATIONS 5.1. Surface testi
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FIG. 5.1. Schematic diagram showing
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Eddy current field extends laterall
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Depth of Penetration & Current Dens
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Please also comment on this illustr
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FIG. 5.2 Directional properties of
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The depth of surface flaws (the dis
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Case Discussion: The corresponding
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5.1.2.2 Types of standard surface t
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(b) Spot probes Spot probes are pro
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FIG. 5.6. A spring loaded probe. Ch
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FIG. 5.5. (a) The core and coil of
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Although it is usually evident by i
Page 37 and 38: FIG. 5.7. Effects of cores and shie
Page 39 and 40: 5.1.2.3 Other types of surface prob
Page 41 and 42: FIG. 5.8. A tangential probe showin
Page 43 and 44: Compare vertical probe with the FIG
Page 45 and 46: Discussion Topic- Why in the tangen
Page 47 and 48: FIG. 5.9. A gap (horseshoe) probe.
Page 49 and 50: Horseshoe probe - maximum sensitivi
Page 51 and 52: A gap (horseshoe) probe - Magnetic
Page 53 and 54: 5.1.3 Testing for surface-breaking
Page 55 and 56: Eddy Current Testing over painted s
Page 57 and 58: Testing Frequency: • 200 kHz to 5
Page 59 and 60: If the fastener is not removed, cra
Page 61 and 62: Following are some examples of spec
Page 63 and 64: Threaded Probe Charlie Chong/ Fion
Page 65 and 66: Eddy Current Testing- Hole fatigue
Page 67 and 68: Hand operated or manual hole probes
Page 69 and 70: If motor driven probes are to be us
Page 71 and 72: FIG. 5.12. Typical rotating hole pr
Page 73 and 74: Bolt hole probes Charlie Chong/ Fio
Page 75 and 76: (c) Aircraft wheels: Aircraft wheel
Page 77 and 78: Aircraft wheels Charlie Chong/ Fion
Page 79 and 80: Automated equipment which will perf
Page 81 and 82: Tangential probe - used in electron
Page 83 and 84: FIG. 5.3 Charlie Chong/ Fion Zhang
Page 85 and 86: Although these blocks can be used f
Page 87: (f) Scan over the appropriate disco
Page 91 and 92: FIG. 5.14 a. Typical weld testing p
Page 93 and 94: Since the eddy currents produced at
Page 95 and 96: For testing, the instrument should
Page 97 and 98: Charlie Chong/ Fion Zhang
Page 101 and 102: Keywords: Typically, the magnetic f
Page 103 and 104: Multilayer structures - of flaws in
Page 105 and 106: 5.1.4.2 Probe and frequency selecti
Page 107 and 108: An acceptable compromise which give
Page 109 and 110: FIG. 5.15. Eddy current signals fro
Page 111 and 112: FIG. 5.16. Spot probes testing a la
Page 113 and 114: ) Sliding probes Sliding probes are
Page 115 and 116: 5.1.4.4 Reference samples Reference
Page 117 and 118: 5.1.5 Conductivity testing and mate
Page 119 and 120: 5.1.5.3 Factors which affect conduc
Page 121 and 122: (b) Alloying. Dissolving any elemen
Page 123 and 124: (d) Cold work Plastic deformation o
Page 125 and 126: (b) Test part thickness The conduct
Page 127 and 128: (c) Edge effect Probes dedicated to
Page 129 and 130: 5.1.5.6 Frequency selection The fre
Page 131 and 132: FIG. 5.19. Impedance diagrams and t
Page 135 and 136: The Characteristic Parameter (PC) i
Page 137 and 138: Example: Calculate the optimum freq
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When eddy current conductivity mete
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(d) Perform conductivity measuremen
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5.1.5.9 Heat treatment of aluminium
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5.1.5.10 Sorting materials by magne
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5.1.6 Thickness measurement of non-
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FIG. 5.22. Methods of obtaining sta
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Non-conducting coating thickness me
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A typical operating frequency to me
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5.1.6.4 Measurement procedure (a) C
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(k) (l) Alternatively, if the measu
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5.1.7 Thickness measurement of cond
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5.1.7.2 Probe and frequency selecti
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5.1.7.3 Signals from variations in
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FIG. 5.26. Part of the display show
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5.1.7.5 Measurement procedure (a) C
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(j) (k) Alternatively, if the measu
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5.1.8 Thickness measurement of cond
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FIG. 5.28 shows the impedance curve
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5.2.1.1 Tube testing probes and the
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The coil(s) in bobbin probes produc
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Bobbin probe eddy current the orien
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To obtain adequate sensitivity to f
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As for surface testing, the test se
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5.2.1.2 Selection of test frequency
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The basis for the selection of test
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FIG. 5.32. Impedance diagram showin
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5.2.1.4 Flaw signals from absolute
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At f 90 , all flaw signals appear i
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5.2.1.5 Absolute probe signals from
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Wobble - A-go-go Charlie Chong/ Fio
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Discussion Topic- Discuss on the fo
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(c) Ferromagnetic conditions at the
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A signal from a ferromagnetic condi
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FIG. 5.36 shows the signal from a f
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Tube Sheet: Baffle Plate Charlie Ch
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Tube Sheet: Baffle Plate Charlie Ch
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(e) Non-ferromagnetic support or ba
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This signal will be modified by any
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(f) Ferromagnetic support or baffle
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FIG. 5.37. The signals from a carbo
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FIG. 5.38. Absolute and differentia
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5.2.1.7 Correlating flaw depth and
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FIG. 5.39. Graph showing the correl
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5.2.1.8 Correlating flaw depth and
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5.2.2 Bar and tube testing using en
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Discussion Topic: This means that p
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FIG. 5.41. The eddy current intensi
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5.2.2.2 Selection of frequency For
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Associated with the f/f g concept i
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The optimum operating point depends
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5.2.2.3 Specific test applications
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(c) Flaw detection Surface flaw ind
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5.2.2.4 Testing ferromagnetic bars
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Ferromagnetic material can be teste
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5.3.2 Equipment Most modern eddy cu
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These standards cover such topics a
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The following example is taken from
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The content of written procedures d
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Charlie Chong/ Fion Zhang
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6.5. Records and reports 6.5.1 Test
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6.5.2 Test reports A formal test re
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Records Charlie Chong/ Fion Zhang
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Calibration Standard A test standar
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Coil, probe A small coil or coil as
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Discontinuity Artificial Reference
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Electromagnetic Testing That non de
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IACS σ IACS . International Anneal
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Material, Diamagnetic A material ha
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Parameter A material property or in
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Phase Lag β (beta), radians or deg
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Resistivity ρ (ro), microhm centim
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Signal A change in eddy current ins
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Space Station Charlie Chong/ Fion Z
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Charlie https://www.yumpu.com/en/br
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Good Luck! Charlie Chong/ Fion Zhan
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