If you own a food manufacturing facility, you’re in charge of producing safe, high-quality products that consumers love. This means passing each item through rigorous quality testing. Metal detectors allow you to scan for dangerous contaminants that might otherwise enter your products during production so you can eliminate hazards before they reach the shelves.
This may sound ideal, but you must understand this equipment’s limitations before you rely on it for complete food safety and quality. So, what metals cannot be detected by a food metal detector? Below, our team at TDI Packsys explains potential detectability concerns with metal detectors and solutions your facility can implement to maintain quality control.
How Do Metal Detectors Work?
Before we can dive into the complexities of which objects your equipment can or cannot detect, you need to understand the basics of how these machines function. Metal detectors operate using electromagnetic induction. They typically contain a series of coils that emit a magnetic field and sensors that can detect specific disturbances in that field.
These disturbances arise when metallic objects within the magnetic field produce eddy currents, essentially creating their own miniature fields that interfere with the original one. The detector picks up on these interferences, ultimately identifying the metallic objects within the specified field. To explain this in simpler terms, your food product would pass through the detector, and you would receive a signal if it identified any scraps of metal.
The strength of the detected interferences and the effectiveness of the detector ultimately depend on the type of metal being scanned, as all metals have different conductivity levels and magnetic properties.
Looking at Hard-to-Detect Metals
So, what metals cannot be detected by a food metal detector? The following materials often prove to be more problematic for electromagnetic scanners.
Stainless Steel
Stainless steel offers renowned corrosion resistance and durability. The alloy usually contains a mixture of carbon, chromium, and iron, resulting in very low electrical conductivity levels, meaning its magnetic properties are also quite lacking. Its lack of corrosion and oxidation factors may make it a preferred choice for many applications, but these properties lead to a weak signal, low electrical conductivity, and poor magnetic permeability.
Stainless steel detection limitations depend on the specific alloy contents. Metals with higher nickel and chromium contents often offer lower detectability rates than those with high iron levels. As electromagnetic scanning technology advances, many modern detectors can locate certain low-conductivity contaminants, but you still cannot rely on this technology for 100% accurate results.
Titanium
Titanium is a strong, lightweight metal often used for canning. Like stainless steel, titanium has low conductivity levels, creating numerous challenges in detection. The metal’s low magnetic permeability and premier corrosion resistance may offer excellent benefits for food production & packaging, but these same properties allow titanium contaminants to pass right through electromagnetic scanners.
Non-Ferrous Metals Like Aluminum and Copper
Alloys fall into two major categories: ferrous and non-ferrous metals. Ferrous metals contain high iron contents, offering incredible magnetic capabilities though practical downsides like corrosion concerns. Non-ferrous metals contain little to no iron, so they are not magnetic and do not rust or corrode.
Some of the most common non-ferrous metals are aluminum and copper, both offering very low electrical conductivity levels and weak magnetic fields. Electromagnetic detectors may be able to identify larger pieces of these metals but often fail to locate small fragments.
Aluminum is quite common in food processing facilities, as it’s one of the primary materials used for canning. Because of this implication, it’s incredibly vital that facilities overcome this scanning gap so they can identify all potential aluminum contaminants.
Understanding Common Detection Challenges
What metals cannot be detected by a food metal detector? The answer is a bit more nuanced than you may realize. Aside from specific conductivity levels, detection rates also depend on factors like the orientation and product effect:
The Orientation Effect
Alloy type isn’t the only concern when analyzing electromagnetic detector weak points. Contaminant shape and orientation can also affect detectability. For example, thin wires or flakes within a food product can align with the electromagnetic field, allowing them to remain virtually invisible.
This may seem like a rare possibility, but thin shavings tend to be one of the more common metallic contaminants found in manufacturing facilities. As equipment wears down, minor metal fragments can splinter off, potentially landing in the product. The same can happen with rough edges of product packaging, ultimately compromising safety and quality for the end-consumer.
The Product Effect
Specific food properties may also interfere with detection. For example, foods with high moisture or salt content can mask metal signals.
The product effect may also come into play, as some foods have the ability to produce minor magnetic fields, ultimately masking potential readings from contaminants. Product effect interference is most common with fresh meats, poultry, and fish.
To add even more complications, the product’s packaging may obstruct the magnetic field. For example, metalized films, foils, or cans can hide contaminants within the product, preventing accurate signals.
Electromagnetic Detectors vs. X-Ray Inspection: Which Works Best?
Food x-ray technology leverages electromagnetic radiation to send waves through the object. These x-rays absorb, transmit, and scatter around the object’s properties to identify various materials and foreign objects. Once the scan is finalized, you receive a clear 3D image depicting all contaminants inside the item.
Unlike metal detectors, x-rays can identify nearly all types of foreign objects, including bones, glass fragments, organic materials, and more. They excel at identifying any potential hazards inside the product. While x-rays can identify metallic fragments, they still struggle to pick up signals from non-ferrous metals, particularly smaller items with very low conductivity levels.
Electromagnetic detectors generally provide more precise detection capabilities for metallic contaminants, despite their potential drawbacks. X-rays can help you overcome many hurdles, allowing you to identify all other potential hazards, such as stray pieces of glass that could make their way into final products. Because each detection system offers pros and cons, the safest and most comprehensive approach is often to combine both.
Best Practices and Mitigation Strategies for Food Manufacturing Facilities
Now you know the answer to “What metals cannot be detected by a food metal detector?” so you’re likely wondering how you can mitigate risks at your facility. We recommend these best practices:
Calibrate Equipment and Incorporate Multi-Frequency Technology
While standard detectors may not be able to identify low-conductivity metals, the most modern systems excel at locating stainless steel, aluminum, titanium, and copper. We recommend incorporating advanced multi-frequency technology to improve sensitivity rates. These scanners allow you to fine-tune calibration levels for improved detection rates.
For example, you can customize your sensitivity level for the exact metals you’re concerned about at your facility, whether that be iron, aluminum, or anything else. With regular testing and optimization, you should see improved detection capabilities.
Combine Technologies for Better Coverage
Combining technologies allows you to reduce risks while enhancing safety protocols. You can implement x-ray scanners and electromagnetic detectors to ensure no contaminants make it through your production line. Metal detectors provide refined identification of most metallic fragments, while x-rays allow you to locate other materials, ensuring nothing harms your end-consumers.
Follow All Recommended Preventive Controls
Prevention is the best way to eliminate contaminants from your products. Common options include the following:
- Leverage magnets to eliminate fine particles: Magnet separation systems allow you to remove even the finest particles from raw materials before they enter the later stages of the production process. This can also reduce issues with orientation concerns.
- Use sieves for low-conductivity contaminants: Because low-conductivity metals may pass through detectors, consider running raw materials through sieves before continuing through production to catch potential contaminants early on.
- Follow best practices when refining your equipment: Maintain equipment and packaging materials following all best practices to prevent metal from splintering or shaving off into products.
Conduct Routine Staff Training and Maintenance
Detection equipment offers premier imaging, though human intelligence and oversight must not be overlooked. You must still conduct regular staff training to ensure your team knows how to handle all equipment correctly. Minor errors in machine handling or calibration can lead to contaminants passing right through your production line.
Your team should know how to perform proper maintenance checks, when to recalibrate machines, what errors to look for in faulty signals, and when to perform quality control checks. Whether you’re considering x-ray inspection as an alternative to electromagnetic scanning or planning to install both systems, be sure to integrate all technology correctly for optimal results.
Are You Ready To Upgrade Your Detection Equipment?
What metals cannot be detected by a food metal detector? Now you know the weak points of electromagnetic scanners and effective strategies for mitigating these concerns.
If you’re interested in upgrading the detection equipment at your food processing facility, you’ve come to the right place. At TDI Packsys, we offer cutting-edge x-rays and metal detectors you can rely on. Call us today at (877) 834-6750 to learn more about our customized inspection solutions.
