Metal Detection: Multiscanning Turns Up Frequency for Food Industry

A recent advancement in metal detection enabled detection at two frequencies simultaneously, essentially performing like a low and high frequency detector in one. Although the dual-frequency metal detection approach improved overall sensitivity, the combination of frequencies that could run simultaneously was still limited. The opportunity to miss metals with frequencies between or on either side of the dual setting still led to compromise that left quality managers wanting more.

The Advent of Multiscanning

Multiscan technology is said to be the long-awaited innovation in metal detection. Metal detectors with this capability can identify contaminants that are up to 50 percent smaller in volume than previous technologies, including food items with high product effect. With multiscan technology, the CCP can scan up to five adjustable frequencies, raising the probability of detection exponentially. Essentially, it’s the equivalent of having up to five completely adjustable metal detectors back to back in a production line.

Multiscan detectors don’t continuously broadcast the five frequencies simultaneously. If they did, the power requirement would be too high and expensive. Instead, the frequencies are scanned thousands of times per second, equivalent to broadcasting simultaneously without requiring as much energy.

Another benefit of multiscan technology is complete flexibility to set frequencies and the associated detection parameters. This is important given that the interaction of the product and metal in all applications is different, depending on factors such as the ingredients in the product, the type of packaging, the product temperature, and variation in all of the above. Most times these interactions are impossible to predict too. With multiscan technology users can make changes in software, selecting the appropriate five frequencies in the 50 to 1,000 kHz range. If a quick test shows detection for an application is best in the 400 to 600 kHz range, the user can easily select five frequencies in that range to maximize performance. To counteract product effect, the user can simply select a lower frequency range, such as 100 to 250 kHz. Different combinations can be selected for different products and they can be changed at will at any time. Multiscan detectors are based on the idea that there is no perfect frequency, and that the best range of frequencies changes depending on the application.

A not-so-obvious benefit of multiscan technology is that it can be used to address an all-too-common metal detection problem–electromagnetic interference (EMI), which can happen in almost any factory at any time. EMI is an invisible field typically generated by a motor or variable frequency drive that moves through the air into the metal detector aperture, causing interference with the detection signals. EMI can come from a variety of other sources in a harsh industrial setting and the aperture can’t be shielded because it’s where the products pass through. Users can simply look at the screen on an advanced multiscan detector to see which frequency or frequencies are affected by EMI and adjust accordingly. This can be done in a matter of minutes and doesn’t require a specialized skill set.

Finding the Best Metal Detection Solution

There is no “one size fits all” approach to metal detection. The best protection against metal escapes is ensuring that the solution you implement is the right one for your products. Even with advanced multiscan technology, it’s critical that manufacturers consider their unique systems, processes, equipment, and product types before making a final decision about which technology to deploy and how.

To ensure future detection performance, a best practice is to have the metal detector manufacturer conduct controlled tests on the detection equipment of interest. The test must simulate, as closely as possible, how product will ultimately be inspected on an actual processing line. Product-specific factors such as temperature and package configuration must be replicated.