Food metal detectors are one of the ways that food processors help ensure only quality, metal-free food products are being shipped to consumers. The newest technology to be incorporated into food metal detectors is a Multiscan capability, where the critical control point scans up to five completely adjustable frequencies to find metal types and sizes previously undetectable. How does it do it? Here are some frequently asked questions and answers about the technology.
A. Multiscan food metal detectors utilize a true spectrum of frequencies along with new signal processing, thus reducing the probability of an escape to near zero. The critical control point (CCP) scans up to five completely adjustable frequencies to find metal types and sizes previously undetectable. It’s like having up to five metal detectors back to back in a production line. It reduces the probability of an escape by many orders of magnitude.
A. While metal detection can be challenging even with five frequencies, Multiscan technology can be easy to use. Multiscan metal detectors utilize wizards, graphical displays, and reports to help with set-up, use, and adjusting performance.
A. You get immediate feedback. When running, Multiscan allows you to view all the selected frequencies in real time and pull up a report of the last 20 rejects to see what caused them.
The Multiscan metal detector automatically balances frequencies electrically. While it takes a few minutes the first time, it has a big impact on performance. To save time, the last balance data is used unless a new frequency is added. The software also runs an autobalance process continuously to remove the final errors caused by very small imbalances. There is even a balance diagnostic screen for advanced users to make sure balance is correct and there isn’t an internal problem with the metal detector.
A. “Product effect” occurs when a product has a conductive property which affects the magnetic field generated by the metal detector. This is typically found in high-salt, high-moisture products. And it can be a challenge to food safety.
The best way to overcome this challenge is to utilize additional frequencies. Food metal detectors that are equipped with Multiscan technology enable operators to pick a set of up to five frequencies from 50 kHz to 1000 kHz. The technology then scans through each frequency at a very rapid rate. Running five frequencies helps to get the machine close to ideal for any type of metal you might encounter. Sensitivity is optimized, as you also have the optimal frequency running for each type of metal of concern. The result is that the probability of detection goes up exponentially and escapes disappear.
A. The best frequency is the one that catches the metal, but unfortunately, different sizes of the same metal have different magnetic and conductive reactions. And the shape, orientation, and position of the metal can change the resulting signals in a metal detector. The best metal detector technology is the one with the ability to scan multiple frequencies at once. The more, the better.
A. Using up to five frequencies does not mean Multiscan technology will create five times the number of false rejects. If you discover that any of rejects were false you can quickly jump to the controls that need adjustment.
A. It is widely understood that ferrous is the easiest metal to detect due to its magnetic properties. Magnets attract iron. An electromagnetic field reacts most when a ferrous metal is in it, and the lower the frequency the greater the reaction.
Conversely, stainless steel, which contains only a small amount of ferrous metal, has little or no magnetic property. To find stainless steel with a metal detector requires running a high frequency because the high frequency field induces a current in the stainless steel which creates a new field that interacts with the original field in the metal detector to create a signal.
A. Every detection system has a probability of an escape. The type of metal, its shape, position, product effect, etc., all are factors in detecting a metal contaminant. Assume in the past you have found that 1 out of 1 million packs (1 ppm) incurs an escape. At a pack/second, 16 hours a day, 5 days a week that is an escape about every 3–4 weeks. That escape could cost thousands to millions of dollars. Multiscan technology reduces that number significantly, because it’s like having five metal detectors back to back running the same package at different frequencies.
A. Small metal foreign objects have very small signals, and the metal detector is operating in a factory that has many possible noise sources that can confuse the metal detector electronics and software. Some of these sources include:
Read A Practical Guide to Metal Detection and X-ray Inspection of Food, a newly updated and expanded foreign object detection ebook for the food industry, to: