Metal detectors and X-Ray inspection systems will both detect metal contaminants but due to the difference in metal characteristics each technology is sensitive to (X-Ray is sensitive to the density of contaminants while metal detectors are sensitive to the electrical conductivity of contaminants) it will be found that depending on the metal type, for non-magnetic metals particularly, one technology or the other may offer better capability.

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The chart below shows the relative ease of detection of various non-magnetic metals - note that all metals shown, to some degree, are detectable by both technologies but those appearing more towards the top and left lend themselves to detection with X-Ray, while those appearing more towards the bottom right favor metal detection technology.