No More False Reads?

Improvements in sensors and software allow metal detectors to approach that goal.

By David Phillips, Plant Operations Editor

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New software and sensor technologies combined with increased demands from food makers have pushed metal detection technology toward a new threshold that may completely eliminate false reads.

"Most new food safety standards call for the reduction of contaminant size detection, in addition to shooting for near-zero false rejects," says Mike MacDonald, senior technical support and trainer at Thermo Fisher Scientific Food, Minneapolis. "Technology — such as our multicoil metal detector design and IntellitrackXR — can help customers get there."

That technology is a standard feature in all Thermo Scientific Apex metal detectors, MacDonald says, and it is a signal processing approach that addresses the unique challenges of detecting smaller-diameter metals in products that have a lot of so-called "product effect."

Similar technologies are available from Mettler-Toledo Safeline, Tampa, Fla., says Rob Rogers, senior advisor for food safety.

"PowerPhasePro Select metal detectors have eight fixed frequencies and two customizable frequencies, allowing inspection of multiple product types on a single system," Rogers says. "Our ProdX software offers data collection and reporting capabilities, which are very important features that assist facilities with compliance."

As manufacturing has become more automated, metal detection has played a role. Touchscreen controls have made the devices easier to use, so operators can integrate that operation into a series of other tasks. New regulations such as the Food Safety Modernization Act require the detection of ever-smaller foreign materials and more ability to report data. New machines from companies like Bunting Magnetics, Newton, Kan., allow for both of those requirements to be met.

"Most detectors have the ability to learn a product after several passes of material through the coil," says Rod Henricks, product manager for metal detection at Bunting. "Once these product learns have been registered, you can store these settings under a batch or SKU number."

Reports can be generated from these activities showing the times the unit was running, the product identification and a date/time stamp of metal detection events, or even other happenings that would impact the performance of the detector, Henricks notes.

Metal detection is one component of any food manufacturer's efforts to prevent contamination of product. It is typically used in conjunction with X-ray and checkweighers (often combined in a single unit) providing the added benefit of more accurate fill measurement. Companies with the largest national brands are more likely than others to employ the latest equipment and to insist on multiple layers of protection, says Thermo Fisher's MacDonald.

"The big packaged goods companies have the most valuable brands to protect, therefore they tend have a metal detector on a line," MacDonald says. "It's usually a newer, high-performance unit and almost always is metal detecting an individual box or bag prior to a case packer. This doesn't vary much by food vertical market like meat, bakery, snacks, confectionary, dairy, etc. All these businesses have about the same risk of metal contamination."

Positioning equipment after filling and capping, but before secondary packaging is the most widely practiced placement of metal detection. This allows a package to be inspected after any threat of further contamination has been removed. That said, there may be some justification for using metal detection at other points along the line, as well.

"The implementation of metal detectors protects not just companies but also downstream equipment and processes too," says Mark Gorzelski, a spokesman for Sartorius Group,  Bohemia, N.Y. "Undetected foreign bodies on a production line can cause untold levels of damage as well as instigating lengthy and costly downtime periods. Because of this, HACCP regulations stipulate that strict checkpoints must be instigated along process lines in order to search for metal contamination."

Suppliers continue to roll out new technologies that help food processors get more from their inspection programs.

"At Pack Expo we will be promoting imagePhase," says Henricks of Bunting Magnetics. "It's the accomplishment of hard work on components and software development. This new feature allows for a much more defined pattern of product learning, and does not generalize a threshold above or below product effect."

And there will be more to come.

"We believe next generation metal detectors will have easier-to-use and more robust interfaces, such as remote access and troubleshooting upgrades," adds MacDonald. "These modifications are being driven by plant staffing reductions, which will force systems to be simple to use and easy to keep running."

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