Protecting brands is one of the most important functions that a food manufacturer performs, but a product reputation could be lost with just one safety recall. Developing and maintaining an effective, verifiable inspection program is no longer an option for processors; actually, it never was.
Metal detection is an effective and relatively inexpensive solution. While price, delivery and other commercial considerations are important, technical performance must be the primary factor when evaluating a metal detector to trust with a brand's reputation.
Metal detection sensitivity needs often depend on the operation. For example, if a metal detector's primary function is to protect a key piece of equipment, such as a sheeter or slicer, the goal would be to eliminate metal that is large enough to damage the equipment. In another part of the line, a different level of sensitivity would be required to inspect a bulk flow of product. And because final package inspection is usually the most demanding, a higher sensitivity would be needed to protect your product before reaching the marketplace. Your plant's quality control group should have specific sensitivity targets for ferrous, nonferrous and stainless steel (even difficult to detect type 316) contaminants for each inspection operation. These targets should be communicated to the metal detector manufacturer so that they can select the appropriate equipment for each application. Remember to be flexible to achieve realistic and achievable goals within your budget.
Start by evaluating your inspection area. Is it wet or dry? How much does the temperature vary? Selecting a metal detector suited to your operating environment is critical. One of the most common causes of metal detector failure is water intrusion into the electrical components. If there is a washdown regimen in the plant, is it high or low pressure? Pay attention to the IP rating. An IP65 washdown rating means that the metal detector can withstand low pressure washdown with ambient temperature water; an IP69K rating means sustained high temperature and pressure. But beware: these ratings are typically self-reported. The manufacturer's reputation in the industry for its equipment's ability to withstand washdown can be a good indicator.
Does the washdown include caustic agents? If so, careful attention should be given to the specific alloy of the stainless steel used for the metal detector's case. Type 316L is more resistant to these caustic agents. For dry environments, is the finish of the metal detector painted? Placing a painted surface in the product stream could eventually contaminate your products with chips of paint. Also consider impact resistance. Plastic covers and membranes are subject to wear or impact penetration. A robust display screen and keyboard help avoid downtime and parts replacement costs.
Will the metal detector be a standalone piece of equipment or will it need to be integrated into the plant’s network, providing periodic data reporting for a statistical package? Does the unit have ready-made software that can provide these functions? Is it Ethernet ready? Some manufacturers provide software packages that allow for remote programming and diagnostics via laptop, including oscilloscope emulation via Bluetooth, without the need to open the power supply cabinet.