How magnetic separators and metal detectors work together

Correct procedures and correct equipment for metal fragment control are essential to maintaining food safety initiatives and protecting your product and brands.

In years past, magnetic separation and metal detection were mainly for protection of machinery. Today, food safety is paramount. Protection of products, consumers and brands has never been so important. It can be demonstrated that both high-grade rare earth magnets and efficient metal detectors are essential to satisfying today’s product security requirements in the food industry and greatly complement each other to ensure metal risks are significantly reduced.

Many companies only use magnets, some only use metal detection. Both are equally important… let’s put them into focus.

The role of metal detectors

Metal detectors, as taught in TAFE colleges, may still be overemphasised 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 RE80 magnetics which can present 10–12,000 gauss strength to the product at CCP or final packing locations.

A metal detector will reliably indicate the presence of stainless steel/brass nuts and bolts, stainless steel nuts and washers, copper wire, aluminium foil and other even larger non-ferrous contaminants — this is where the metal detector really shines.

Although theoretical indications on 0.04″/1 mm spheres of iron can be achieved in ideal circumstances, it should be remembered that 316 stainless steel is a very different story. The shape of the stainless steel piece can make it difficult to detect at certain orientations as it passes through the aperture of the metal detectors. In practice, this can sometimes mean detection of only 0.12″/3 mm or larger particle size. This can mean fine wires or other dangerous smaller fragments remain in the outgoing products.

However, stainless steel fragments and wires of 0.12″/3 mm size and under are usually work hardened. This means such fragments can be extracted magnetically along with other contaminants such as magnetic stone — this is where magnetic separation equipment is essential to ensure maximum product security.

The role of magnetic separation equipment

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 units. Both have limitations but both are necessary and complement each other.

Without efficient magnets, there is a high risk that fine ferrous metal and fine magnetic fragments will escape even the most sensitive metal detectors. Without efficient magnets, larger pieces will be detected by the metal detectors but excessive product rejection can occur where the detector is properly calibrated. 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 RE80 magnets conforming to the current HACCP International Magnet Standard.

They may be small, but even fine fragments can cause product recalls and other consequences.

For more information: www.magnattackglobal.com/magnets

Image courtesy of MAGNATTACK.