Electromagnetic Testing - Eddy Current Testing Applications Chapter 5 & 6

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5.1.5.5 Factors which affect the conductivity reading (a) Lift-off Conductivity meters and impedance display instruments which include a digital conductivity measurement facility normally provide lift-off compensation for lift-off values up to at least 0.08 mm, so the reading should not be affected by paint coatings up to this thickness or by minor surface roughness. If it is considered likely that the reading will be affected by a coating or surface roughness, conductivity readings should be made on a surface showing the condition of the test part and on a flat, smooth surface to determine if a lift-off correction is required. Comment: Digital conductivity measurement facility normally provide lift-off compensation for lift-off values up to at least 0.08 mm. Charlie Chong/ Fion Zhang
(b) Test part thickness The conductivity reading will be affected if the test part thickness is less than the ‘effective depth of penetration, which, for the coil diameter normally used for conductivity testing (approximately 10 mm), can be taken as 3 times the standard depth of penetration. If there is doubt as to whether the test part is thick enough, it should be tested, if possible, with and without a block of copper held against the far surface. Any difference in the readings indicates that the thickness is less than the effective depth of penetration. Most eddy current conductivity meters operate at a fixed, common frequency of 60 kHz. This is low enough to give sufficient penetration to avoid any contamination of the test surface having a significant effect, and high enough to allow testing of reasonably thin materials. 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
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FIG. 5.7. Effects of cores and shie
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5.1.2.3 Other types of surface prob
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FIG. 5.8. A tangential probe showin
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Compare vertical probe with the FIG
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Discussion Topic- Why in the tangen
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FIG. 5.9. A gap (horseshoe) probe.
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Horseshoe probe - maximum sensitivi
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A gap (horseshoe) probe - Magnetic
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5.1.3 Testing for surface-breaking
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Eddy Current Testing over painted s
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Testing Frequency: • 200 kHz to 5
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If the fastener is not removed, cra
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Following are some examples of spec
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Threaded Probe Charlie Chong/ Fion
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Eddy Current Testing- Hole fatigue
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Hand operated or manual hole probes
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If motor driven probes are to be us
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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 and 88: (f) Scan over the appropriate disco
Page 89 and 90: 4.1.3.5 Testing in-service welds in
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: (d) Cold work Plastic deformation o
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
Page 139 and 140: When eddy current conductivity mete
Page 141 and 142: (d) Perform conductivity measuremen
Page 143 and 144: 5.1.5.9 Heat treatment of aluminium
Page 145 and 146: 5.1.5.10 Sorting materials by magne
Page 147 and 148: 5.1.6 Thickness measurement of non-
Page 149 and 150: FIG. 5.22. Methods of obtaining sta
Page 151 and 152: Non-conducting coating thickness me
Page 153 and 154: A typical operating frequency to me
Page 155 and 156: 5.1.6.4 Measurement procedure (a) C
Page 157 and 158: (k) (l) Alternatively, if the measu
Page 159 and 160: 5.1.7 Thickness measurement of cond
Page 161 and 162: 5.1.7.2 Probe and frequency selecti
Page 163 and 164: 5.1.7.3 Signals from variations in
Page 165 and 166: FIG. 5.26. Part of the display show
Page 167 and 168: 5.1.7.5 Measurement procedure (a) C
Page 169 and 170: (j) (k) Alternatively, if the measu
Page 171 and 172: 5.1.8 Thickness measurement of cond
Page 173 and 174: 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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