X-ray systems are becoming increasingly popular as the first choice for product inspection systems, due to the superior performance.
Recently Mike Rothwell, Sales Manager for X-ray Inspection Systems at Loma Systems, spoke to UK-based magazine Food Processing about the benefits of X-ray versus metal detection.
What is the benefit of X-ray over Metal Detection?
Manufacturers who use foil or metalised film packaging for their products find X-ray highly advantageous over metal detection. The metal in the packaging creates a significant effect of the signal generated by the product as it passes through a metal detector. This generally means that for metalised film packaging stainless steel sensitivity is relatively low, typically 4-6mm before it can be detected.
For foil packaging the signal generated is so high that it overloads a standard metal detector and the only available option is a bespoke Ferro-search metal detector that is only capable of detecting ferrous metals. When you consider that most food production factories utilise stainless steel throughout for hygiene reasons, you can see that where foil or metalised films are used, metal detectors are of limited benefit.
X-ray machines on the other hand operate by inspecting the density of the product and packaging, as the foil or metalised film is very generally very thin it has little or no effect on the overall density of the product. So under these circumstances X-ray inspection systems are essential for an accurate and reliable reading.
Are X-ray systems suitable for all products and packaging?
Generally X-ray systems are suitable for inspecting most food products as they have a low and variable density. However, the overall height of the product (and therefore the distance the X-ray has to pass through) has to be taken into consideration.
Products which are presented in bulk form such as cases or euro boxes are more difficult to inspect and will typically have lower inspection sensitivity. If dense materials such a glass, ceramic and porcelain are used then the sensitivities achieved may be reduced. In these cases where dense packaging is used it may also be necessary to go to higher power levels to achieve the desired results.
The shape and positioning of the product as it passes through the machine may determine the type of X-ray machine used as products which are taller than their base tend would better be inspected by using a side shoot rather than the standard down shoot machine.
Do X-ray systems perform to the same quality, accuracy and speed as a Metal Detector?
It is fair to say that in most applications an X-ray machine will outperform a metal detector by identifying the size of the metal contaminant and any additional dense contaminant, whilst ensuring product integrity. Furthermore, standard X-ray machines can inspect with no loss of performance at line speeds. Loma’s X-ray systems are designed to operate continuously at speeds in excess of 600ppm or 90m/min sufficient for most production lines.
For more information about X-ray or Metal Detector systems call Inspection Systems on 1800 354 302.