How To Choose The Best Metal Detector For Your Products?

By Todd Grube, Inspection Systems Manager, Heat and Control, Inc.

Protecting your brand in the marketplace is one of the most important functions a food manufacturer performs. But all the investment to establish a reputation for product quality could be lost in the event of one safety recall. Developing and maintaining an effective, verifiable inspection program is no longer an option for processors. Metal detection is an effective and relatively inexpensive method of protecting your customers and your brand. While price, delivery and other commercial considerations are important, technical performance must be the primary factor when evaluating a metal detector to trust with your brand reputation.

Product effect is an important factor in the selection of a metal detector. If the product is conductive (usually because it contains water or salt) it will generate a signal which affects the electromagnetic field of the metal detector. This will produce a false reject . Dry or neutral products generally do not emit such a signal. If product effect is a factor, then the correct frequency must be selected in order to help move the signal of the product effect away from the signal of the contaminants. A metal detector that has a single frequency may not accommodate much product variation and so may not be suitable for a processor that inspects a variety of products. This could include, for example, the difference between the product effect of a frozen product and that of the same product when inspected at a higher temperature. On the other hand, a three frequency metal detector will allow the inspection of a greater range of products on the same metal detector.

The most sophisticated metal detectors on the market today use multi-spectrum technology. Instead of relying on just one frequency, a spectrum of multiple frequencies work simultaneously to filter out product signals in a way that is much more effective than a single frequency. In addition, the number of false alarms is greatly reduced.