Traditional methods of testing gravity fed metal detectors and those installed on Vertical Form Fill and Sealing (VFFS) packaging lines typically involve frequent and time-consuming stoppages, potential risks to operator safety and often generate inconsistent results. In many cases, the test methods used do not confirm that the operational specification of the metal detector is being achieved. Mike Bradley, global head of sales (metal detection) at Mettler-Toledo Product Inspection, elaborates how automatic metal detector testing systems can overcome these issues, and improve food manufacturing quality, efficiency and productivity.
The “Drop-Through”, “Fishing Line” and “Test Rod” methods are all routine performance monitoring test processes for vertical metal detection systems. Manual testing often requires teams of operators to put their safety at risk by climbing ladders and reaching over machinery so that they can drop or insert test samples into a throat or gravity-fall metal detector. These test processes are unable to accurately verify the operational specification of the metal detector because they do not confirm centreline testing – the least sensitive part of the metal detector – as the placement of test samples passing through is generally random.
In addition, manual testing processes can carry cross-contamination risks, and can potentially compromise food product quality, as the test samples come into direct contact with the product.
Mettler-Toledo has developed a solution to address these issues, while also helping to improve overall equipment effectiveness (OEE) and productivity – the Automatic Test System (ATS) on Safeline metal detection systems.
ATS is designed for use in vertical food inspection applications such as snacks, crisps, confectionery, infant formula, bulk flour and nutraceutical powders, plus granulates such as sugar and food additives. Test samples are transported, by pneumatic control, up discreet non-metallic tubes inside the metal detector’s aperture to a defined position within the sensing coils. The test samples are then released, simulating the presence of a contaminant in free-fall under gravity. A software algorithm correlates centreline sensitivity with edge of aperture sensitivity, eliminating the random nature of vertical metal detector testing.
The full article is published in the latest edition of Food & Beverage Asia Feb/Mar 2021 issue. To continue reading, click here.
