The Role of Magnets And Metal Detectors In The Food Industry
It can be demonstrated that both high-grade rare earth magnets and efficient metal detectors are essential to satisfying today’s food safety requirements in the food industry.
Metal detectors, as taught in tertiary institutions, may still be overemphasized in the HACCP doctrine in a manner which overshadows the relative importance of Ultra High-Intensity Rare Earth Magnet capabilities in metal fragment extraction. This is especially so since the availability of magnetics conforming in full with the current 0909 MAGSEP standard which will present 10 -12,000 gauss to the product, along with other essential aspects, at final locations. microbial contamination, undeclared allergens, packaging fault, or any other reason.
Of course, only a metal detector will reliably indicate the presence of brass bolts, stainless steel nuts and washers, copper wire and aluminium foil – this is where the metal detector really works well.
Although theoretical indications on 1mm spheres of iron can be achieved in ideal circumstances, it should be remembered that 316 stainless steel is a different story. The shape of the stainless-steel piece can make it difficult to detect at certain orientations. In practice, this can sometimes mean detection of only 3mm or larger particle size. This can mean fine wires or other dangerous smaller fragments remain in the outgoing products.
Stainless steel fragments and wires of 3-4mm size and under are usually work hardened. This means such fragments can be extracted magnetically along with other contaminants such as magnetic stone.
Many respected organisations now share the view that it is of first importance that Ultra High Intensity Magnets should be installed upstream of high sensitivity metal detectors and X-ray equipment.
Without efficient magnets upstream of even the most sensitive and sophisticated metal detectors, it is highly likely that fine ferrous metal and fine magnetic fragments such as work hardened stainless steel may be getting through the undetected.
The causes of rejection in these circumstances are often difficult to locate in bags or bins of bulk product. Consequently, it is much better to pull ferrous and other magnetics out first with efficient magnets conforming in all aspects, to HACCP International Food Safety Standard 0909MAGSEP 1-2010.
Even the smallest fragments can cause product recalls.
Summary
It is accepted that metal detectors work much more efficiently in both wet and dry product when fine magnetics have been scalped out at a moderate but adequate distance upstream of the detector. When such installations have been implemented customers have reported significant reduction in their metal detector activations.