Food manufacturers need to ensure their food is free from contaminants of all types. The inclusion of materials that shouldn’t be there could lead to recalls, negative publicity, and even public safety concerns.
One of the key materials manufacturers want to watch out for is metal, leading many to turn to metal detectors. But do these detectors work on all types of metals?
Many manufacturers specifically want to look out for aluminum. So, does aluminum set off metal detectors in food manufacturing? Unfortunately, the answer is slightly more complicated than a simple yes or no.
Does Aluminum Set Off Metal Detectors?
The answer to whether or not aluminum sets off metal detectors varies. In some situations, and with some metal detectors, it will. In other situations and with other metal detectors, it won’t.
The ultimate result depends on a variety of factors. The metal detector, its settings, any extenuating circumstances, and the exact nature of the aluminum contamination all impact whether or not the aluminum within a food product will set off the detector.
For example, a lower-quality metal detector that a manufacturer has not calibrated to find aluminum will often fail to do so. Meanwhile, a high-quality metal detector, such as a metal detector specifically designed for food safety, will often find aluminum.
Why Aluminum is Hard to Detect
In metal detection, a metal object is usually either ferrous or non-ferrous. Ferrous metals, like some types of steel or cast iron, contain high levels of iron. Non-ferrous metals, like copper and lead, contain far lower levels of iron, if any.
The difference between iron levels is important because iron produces a strong magnetic field. So, metals with lots of iron inside produce a similarly strong field.
Aluminum is a non-ferrous metal, meaning it does not contain much iron. As a result, aluminum is electrically conductive but has weak magnetic fields.
Many metal detectors can detect both ferrous and non-ferrous metals. However, they detect ferrous materials in different ways when compared to non-ferrous metals.
Metal detectors use a transmitter coil to create an electromagnetic field. When the magnetic fields of other metals disturb this field, the machine knows that it detects metal and, thus, sets off an alarm. Because of this, it is harder for a metal detector to find a non-ferrous metal than a ferrous metal.
While it is harder for a metal detector to find a non-ferrous metal, it is still possible. These metals still produce a slight magnetic field; it is just far weaker than the field produced by ferrous metals. So, a metal detector will still detect aluminum far easier than it will detect stainless steel.
However, there are still even more challenges. Interference from other metals makes the hunt for aluminum more difficult. When near ferrous metals, aluminum can often become undetectable in the overwhelming mix of magnetic fields.
Think of it like looking for a specific flower in a field of many flowers. One of the larger flowers may cover up the flower you are looking for, meaning it may be out of sight entirely. Meanwhile, if you were looking for a specific flower in a field of grass, you’d find it immediately.
In this example, the aluminum is like that flower. It is easier to identify on its own. However, in a more complex situation, it may go unnoticed.
Factors Affecting Aluminum Detection
Does aluminum set off metal detectors in all cases? Not necessarily. Since metal detection varies so much, especially when it comes to aluminum, there are a few factors that can either make it easier or more difficult to detect.
Size and Shape of Aluminum Contaminants
Not all aluminum contaminants are equal. Aluminum contamination may come in the form of small metal shavings or a large metal piece. These variations in size and shape also lead to variations in detection.
One of the biggest factors in this regard is size. Larger pieces of aluminum are generally far easier to find than smaller pieces.
The variation here comes from the size of the magnetic field the piece of aluminum creates. A larger piece of aluminum will create a larger field, one that a metal detector is more likely to pick up. Meanwhile, a smaller piece of aluminum will create a smaller field that is more likely to go unnoticed by a metal detector.
The shape also matters. Circular shapes, like coins, are easier to detect. Meanwhile, long and thin shapes, like a nail or screw, are harder to detect.
Composition of Food Products
The food product undergoing testing can also affect whether aluminum is detectable. For example, red meat is naturally conductive. It can lead to false alerts, which makes finding actual aluminum difficult.
In addition, small amounts of aluminum are present in many materials. Plants absorb it while they are growing, and manufacturers sometimes add small amounts to products to improve the taste or texture. As a result, detectors need to be able to differentiate between these minute, unharmful levels of aluminum and dangerous contaminants.
Finally, the packaging matters as well. Packaging with aluminum in it will set off false alarms and make detecting aluminum within even more difficult.
Environmental Conditions
Does aluminum set off metal detectors in all situations? Many manufacturers neglect to account for how environmental conditions impact the search for aluminum. However, a number of environmental factors impact the functioning of a metal detector and its ability to detect aluminum.
So, aluminum does not set off metal detectors in all situations. Factors including excessively high temperatures and humidity may impede aluminum detection.
To prevent this, manufacturers should only use these detectors under appropriate settings. Most metal detectors state the environmental conditions they require for proper operation. When run in these environments, they have a far greater chance of properly detecting aluminum.
Techniques for Accurate Aluminum Detection
While there are challenges in detecting aluminum, manufacturers can take steps to make doing so easier. Specifically, they can use a few techniques to combat the troubles associated with detecting aluminum.
Calibration of Metal Detectors
Since aluminum presents some challenges when it comes to detection, it is important to calibrate the metal detector correctly to detect aluminum. Doing so often requires fine-tuning the machine.
Some machines have an auto-calibration function that works on its own. Others require manual calibration.
The method used matters less than the fact that the appropriate calibration happens. A machine specifically calibrated to look for aluminum or non-ferrous metals will have a far greater chance of finding contaminants.
In addition, it is important to ensure that the metal detector is actively looking for aluminum. Some machines have settings that skip checks for non-ferrous metals entirely. If this setting is on, the machine won’t even attempt to find aluminum within the product.
Adjusting Sensitivity Levels
Non-ferrous metals, like aluminum, produce weaker magnetic fields. So, less sensitive equipment may end up missing these fields.
One way to set a metal detector to look for aluminum is to adjust these sensitivity levels. A machine with a higher sensitivity level is more likely to find aluminum when it is present, while a machine with a lower sensitivity level may miss it entirely.
Because of this, it may seem that metal detectors should simply have the highest sensitivity levels at all times. However, a higher sensitivity level is also more prone to false positives. Scans at these sensitivity levels are more likely to catch naturally occurring magnetism or other unproblematic issues.
So, most manufacturers should not simply use the highest sensitivity level on their metal detectors. Instead, finding the sweet spot, a sensitivity level that will detect aluminum but avoid false positives, becomes a challenge for many.
Utilizing Multi-Frequency Metal Detection Technology
Multi-frequency metal detection technology is more powerful and robust than single-frequency technology. Because of this, it offers some significant advantages when looking for aluminum.
These machines use two different frequency waves to look for metal. One of these is a high-sensitivity frequency, and the other is low-sensitivity.
The high-sensitivity frequency scan will pick up everything, including both aluminum and some false positives. Meanwhile, the low-sensitivity frequency scan will provide a baseline reading to compare the other scans against. When compared against each other, the low-sensitivity results help weed out the false positives from the high-sensitivity results.
With all of this in mind, multi-frequency metal detection technology helps solve the sensitivity issue. It allows a metal detector to effectively find non-ferrous metals, like aluminum, without encountering an unfortunate degree of false positives.
Ensure Food Safety With Appropriate Metal Detection Equipment
Since the answer to “Does aluminum set off metal detectors?” varies based on the specific detector and its settings, food manufacturers need to pay careful attention to their equipment. By choosing the correct metal detection technology and calibration settings, you can better ensure the safety of your products.
Looking for assistance in choosing equipment? Call TDI Packsys in Vernon Hills, IL, at 877-834-6750 and let our experts help you choose a customized solution.
