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29 Cards in this Set
- Front
- Back
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What consist of one or more coils of wire designed to introduce a varying magnetic field into a part to determine effect of test variables on this magnetic field
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Eddy current coils and probes
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Generation of magnetic fields is resulted from what?
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Alternating current flowing through a coil
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Probe and coil selection is determined by what?
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intended use(most fundamental configuration)
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What provides increased resolution of small defects?
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Small diameter probes and narrow coils
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Small diameter probes and narrow coils will detect defects of what length?
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equal to the radius of the probe diameter
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Larger probes or wider encircling coils provide what?
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better averaging of bulk properties using lower frequency for deeper penetration
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Probes and coils must match what?
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the impedance plane bridge circuits in which they are used
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what must be considered when establishing impedance requirements?
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Frequency ranges
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What are the three test coil modes of operation?
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Absolute, Differential and reflection
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Which mode compares one area to another area?
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Differential
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Which mode interrogates only the area under the coil and does not compare one area to another
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absolute
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Reflection mode uses what?
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two separate coils a driver and a receiver
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Probe housing are normally what?
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Cylindrical
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what are the probe housing diameter ranges?
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1/8" to 3/8" in diameter
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Why may a probe housing be shielded?
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to concentrate the field
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Small pointed or rounded tip are best for inspecting what?
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Radii, around fasteners and along edges
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Special probes are designed to inspect what?
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inside of bolt holes
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Eddy current probes and coils can be classified into what three types?
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Contact/surface probes, encircling coils and inside (bobbin type) coils
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Most eddy current testing is concerned with what?
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surface coil/probes
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What are surface probes used for?
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plates, sheets and irregular shaped parts
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most surface probes contain what?
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ferrite cores(fired iron oxide combined with other metals)
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The extent of area to be tested is controlled by what?
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coil diameter
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special housing and guide blocks may be used to do what?
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reduce loss of sensitivity due to probe wobble and lift off
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Encircling coils are primarily used to inspect what?
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rods, tubes, cylinders or wire
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What is evaluated at one time with encircling coils?
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the entire circumference of the specimen
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inside (bobbin type)coils is used for what?
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tubes, pipes or other parts that have accessibility to the inside
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The use of inside coils are restricted by what?
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bends or non uniform diameters
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each type of coil may be arranged in various double or single coil configurations depending on what?
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design of instruments with which they are used.
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what is the NORTEC 2000D+ Eddy current flaw detector?
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a portable, self contained, compact, rugged NDI instrument
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