Metal Detector Test Standards
Metal Detector Certified Test Pieces Can Make A Real Difference
April 5, 2018
Test Pieces in the Food Industry
Using Metal Detection Test Pieces in the Food Industry Helps Put Safety First
June 26, 2018
Metal Detector Test Standards
Metal Detector Certified Test Pieces Can Make A Real Difference
April 5, 2018
Test Pieces in the Food Industry
Using Metal Detection Test Pieces in the Food Industry Helps Put Safety First
June 26, 2018
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Metal Detector
Metal Detection Test Standards

Metal Detection Test Standards

Why Use a Metal Detector and Its Test Pieces In The Food Industry?

The use of a metal detector and test pieces in the food industry has become standard, and with good reason. It is crucial that all food product manufacturers carefully inspect their products to ensure that no contaminants are present. First, this guarantees the safety of their product and the consumer.  Second, it saves money by avoiding a production shut down or paying legal expenses should any contaminated products reach consumers.

Of course, when considering the use of a metal detector in food processing, people might wonder, “Why is this necessary?”  After all, if a manufacturer is adhering to all health and safety standards, why use a metal detector? That couldn’t be further from the truth. Even the cleanest, most well-run facility can have the unfortunate issue of metal contamination.  So really, there is no reason not to incorporate the use of a metal detector.

Contamination

So where is this contamination coming from?  How do metal detector test pieces help find it? There can actually be many different sources of possible contamination within a food manufacturing plant. Unclean working conditions are just one of those possibilities.  In fact, the majority of contamination is not caused by unsanitary conditions or lax work habits.  The greatest culprit is the natural degrading of the manufacturing machinery.

All around a food production plant, there is machinery and a great deal of that machinery is made of metal. Over time, that metal can rust, wear down, or break apart.  And the resulting metal particles can find their way into food as it passes through the machinery. The purpose of metal detectors is to find those particles and prevent affected products from reaching the public.

The Process

The process involved in a metal detector food inspection is really quite simple. Most food production takes place using some kind of conveyor system, gravity feed or inline processing, passing the product through various stages of preparation until it is packaged and sealed. A metal detector should be incorporated, ideally at the very end of this process, to carefully scan each product for the presence of any metal particles. If a particle is detected, then the product in question would be automatically rejected before it can be approved for shipping.

There are several types of metal detectors that food industry technicians can use. The most common, with the goal of detecting ferrous, non-ferrous and stainless steel metals, relies on the principal of “balanced coils” while the other uses a magnetic field system to detect metal typically within products that are wrapped in foil.

The Difference

The difference between the two has to do with the way contaminants are detected. In a balanced coil system, food is “scanned” while the transmitting coil generates a magnetic field. The presence of a metal in the product creates a change in the magnetic field between the receiving coils. In a magnetic field system, the contaminants are magnetized as they pass through.  The magnetized particles then trigger a detection system within the coils that highlights the contaminant.

No matter which system is used, it is absolutely crucial that it be tested regularly.  This is the only way to make sure, in an ongoing way, that it is functioning properly. To do this, test pieces are used in the metal detector food inspection process. These pieces are made from a variety of plastics and contain “seeds” of metal. We sell them variety of sizes and shapes based on the particular demands of your application and the product being tested.

Test Pieces

The test pieces are placed within a collection of finished products, usually toward the end of the pack. For best results, the pack of finished products should be passed through the equipment 3x.  Place the test piece at the leading, middle and end edges of the pack. If your machinery is working properly, it should detect the metal in the test pieces and reject them.

Regal Packaging Services has been providing metal detection test pieces for food industry companies since 1998. We carefully manufacture and certify each test piece so that our customers are guaranteed to get a quality product.  And one that meets the standards of the food industry. And we can customize your pieces to fit your exact specifications.  You’ll know you’re getting the perfect fit every time. So don’t take chances with your metal detector maintenance…come to Regal and get the best.

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3 Comments

  1. Jenna Hunter says:
    December 9, 2019 at 11:49 pm

    It was interesting to learn about how food products should be tested at the end of the production process so that affected products don’t reach the public. I can understand how it could be very important for a business to make sure that their food is safe to consume so that they don’t get sued or charged for anything. It could be really helpful for them to make sure that they can check for metal efficiently so that they know there isn’t any in their product.

    Reply
  2. Print_Advertising says:
    December 24, 2024 at 11:22 pm

    Is there a risk of false positives or false negatives in the metal detection process, and how do manufacturers ensure the accuracy of their food inspection systems?

    Reply
    • brian says:
      December 26, 2024 at 12:57 pm

      Fiona,
      As long as you have calibrated the detector to clean product, the risk for false positives or negatives is as nearly impossible.
      Whatever you are able to detect after that standard is set, you should never get a false positive unless something else is affecting the detector, such as ambient noise (radio interference) in the plant.
      A false negative means metal below your standard is not being detected, and that should never happen unless the testing standard is set too high.
      If, for instance, in a clean product the lowest you are able to detect is 1.0mm Ferrous, then that’s where your testing standard should be set and written into your HACCP plan.
      If you choose to use something higher (larger), then you will be missing the smaller sizes (false negative).
      I hope that helps.

      Reply

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Floatable Thermoform Test Cards

Some applications involve large tubs, vats, or some other type of product travel where it would be nice to have a test piece that floats. Once again, our thermoform cards provide the simplest solution. We simply insert some type of structure that forces the thermoform card to retain air, which, of course, is what makes it float. We have also manufactured floating rods, which are more difficult because there is less space to close in enough air to make the rod float but is doable.

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We took an ordinary plastic “chip clip” as defined by the customer and embedded the contaminant into the clip. The clip can be attached to the product on the line without damaging or opening the product for testing purposes.

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Bone is a difficult contaminant to find because it can vary widely based on the size, age, and calcium content (as well as feed used) of the animal. After working with several customers, Regal Packaging Services offers Pork, Beef and Chicken Bone Simulate. We have a small range of sizes at a variety of depths to simulate whatever you might expect to find in the product. Our recommendation (assuming your x-ray has visual display) is always to start with a multi-card. Using a multi-card gives you an easy way to test several sizes and depths to determine what matches the bone you’re using. Once you’ve made a comparison, testing the card against the bone you’re looking for, you can purchase a card with a single contaminant for regular testing.

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This small pill shaped test piece is used in a system with a vacuum tube that shoots the test piece through the aperture and returns it to the “home” base. Your system may never be like it, but the point is that we can make a customized solution no matter how unusual or impossible it might seem.

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As you may have seen in some of the other thermoform card descriptions, we can put nearly as many seeds as you can imagine on a single card. Pictured here you will find a wide variety of configurations and contaminants. Just let us know your specs: size of the card (up to 8” x 8”) along with size and type contaminant(s) and we’ll get you a quote as quickly as possible. Working with a multi-card is especially helpful when you are looking for multiple types of contaminants or when you want to determine what size of the same contaminant you are able to detect. In that event, once the size is chosen, you can order individual card(s) for regular, standard inspection and detection.

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There are a wide range of applications that require a test piece much longer than our standard 5” or 6” Testrods. We can make up to 3/8” x 34” or 1/2” x 34” rigid test pieces which can then be extended well beyond that length with a “handle” made of acetal cylinder larger than the 3/8” or 1/2” extension. In the photos, we used a 1” x 24” cylinder handle with a 3/8” x 24” inch extension.

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Test pieces can be made in a variety of sizes and given a pointed end in applications that require the contaminant (metal) to be inserted into a food package such as sugar or some other soft packaged food product. This allows the metal to reach the center of the aperture.

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Double-End Test Whips are also available, with metal in both ends. One consideration is to make certain that the whip is long enough to keep the metal on the non-testing side of the whip outside the metal free zone of your detector. If you insert, for instance one end of a whip with 2.0mm and 3.0mm Ferrous, you need to make certain that the 2.0mm metal doesn’t affect the detection of the 3.0mm metal (and vice versa). If the 3.0mm metal is inside the metal free zone, then the detector will be reacting to the 2.0 as well as the 3.0 as if they were combined.

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Multi-seed laminate test cards are designed for seeds 4.0mm or less. Multi-cards are useful in x-ray inspection to determine what sizes and types of contaminants your system can achieve. They can be especially useful in temperate environments and applications. If your application is rugged or wet, or your standards are larger, we recommend our thermoform multi-cards.

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We can simulate a variety of packaging in an application where you need the test piece to mimic what is traveling down the production line. In this case, we manufactured a clear “package” with the seed inside. With this method, the customer is able to reject the container appropriately, and, in the event the package is not rejected, it is easily seen by the line worker for manual removal.

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There are two types of “candy bars” pictured here – one similar to a flat candy bar and the other in a custom, near perfect copy of a candy bar. Since we’re now able to produce many variations using colored material, the copy was made in red (Fe), green (NFe) and blue (SS 316). We have the equipment to accomplish nearly anything you can imagine, and these kinds of designs are proof positive.

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Need a test piece that looks and handles like chicken nugget? We can do it. Interestingly enough, in this situation, our first version for the customer left too much “void” in the hole where the metal was placed. Given the sensitivity the customer system was using, the void had the effect of causing false positives. We were able to minimize that hole and supply the test piece with almost no void. It’s an example of how we can work with you before, during and after manufacturing to ensure all the specifications were met.

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Our standard acetal card is 2 1/4"x3 3/8,” but if needed, we can cut that size down to as small as 1 1/4” x 1 1/4” (with limited engraving). If a larger card or a card with multiple seeds is needed, see our Custom Shape-Size Blocks and Tablets.

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This distinctive test piece was created to mimic an actual hamburger patty. The customer supplied photos of the raw product, which we were able to reproduce and then we placed blue glove contaminant. Using this configuration, the customer was able to determine what size piece the vision scanning system could detect with the raw burger as the background. Had they simply used a blank card with the glove, the system could easily have achieved contaminant rejection, but they needed to be sure the system could “see” the blue against the product itself.

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A card with 100 seeds in a 10x10 configuration is used to place beneath whole chickens on a production line. This gives the x-ray system operator the ability not just to see IF the equipment can detect the metal in the card, but also WHERE the equipment can detect it. If there is a problem, the operator (or company) can make any changes necessary to achieve the end goal – safe chicken in this case. This card really highlights another valuable facet of our thermoform cards.

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In this scenario, a company processing sugar needed to have a “bag” simulated with the same weight in order to accurately fall through the reject mechanism. A lighter test piece had the risk of passing over the reject mechanism.

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Our standard cubes are 1” and 1.5,” but we can also manufacture other sizes if needed. The cubes shown here are 1/2" in dimensions. Cubes can be helpful in applications where a ball or cylinder may bounce or roll away during testing, making their retrieval difficult, or, in some cases, present a hazard to the product or production equipment.

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This is a test piece that is dropped into a bottle. It’s designed so that the metal appears in the center of the aperture when testing the metal detector. In addition, the round stop makes the test piece easily removable after testing.

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Hexagonal Shaped test pieces can be very useful in places where a cylinder or ball might roll or bounce around a production floor whether dropped by a line worker or ejection from a reject mechanism. Hexagons are similar in weight to the 1inch cylinders without having the smooth, rounded cylinder edge.

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Our customer in this plant needed a test piece with a thickness less than 5.0mm. Because we have the capacity to customize sizes and shapes, we were able to mill down a product that met their specifications. That’s always our goal, meeting the specs you need for your product, testing environment and contaminants.