We are manufacturer of ready meals for a major retailer. One of our CCP is MD.we also have a line where only x rays is used. On this line same checks are done as on other lines( Fe, non Fe and SS).Is it ok to check Non Ferrous on this line like other lines where only metal detector are installed? We use x Ray line to pack meals in aluminium foil containers. Please share your expertise. Thanks. Martinblue
Posted 02 November 2013 - 02:07 PM
For MD we are using Fe/non-Fe/SS 1,2/1,5 and 1,8mm on each line (biscuits and cakes).
Posted 08 November 2013 - 12:16 PM
I have found it common in the UK food industry (where both traditional metal detectors and X-ray are used in the same plant) to use the metal detector Fe/NFe/SS samples for both type of machines. I assume that the X-ray has been purchased to satisfy a retailer COP in which case the primary reason for its use is to detect SS. This type of metal (unless low grade magnetic SS) cannot be detected using traditional metal detectors when the product is packed in aluminium foil.
The reason metal detectors are checked using these materials (Fe/NFe/SS) is that they detect the magnetic and/or conductive qualities of the metals and the level at which these can be detected depends to large degree on the product being inspected. SS is not magnetic and a poor conductor so you usually find that the size of SS needs to be bigger relative to Fe and NFe before it is detected. With X-ray it is the density of the metal which is the determining factor, Fe NFe and SS have similar levels of density so you will find that the smallest sample size (usually Fe in the chilled food sector) will also be the size detectable for NFe and SS. In other words you only (in theory) need to test an X-ray with one metal all the others of similar density will (or should) be detected. This argument does not apply to low density metals like aluminium.
If the X-ray machine was purchased to detect non metallic contaminants like glass or stone (ceramic) then my view is they should be checked/validated using the type of material(s) the X-ray was bought to detect.
Hope this helps
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