Culture of Food Safety
A Culture of Food Safety with the Right People
June 24, 2021
X-Ray Basics
X-Ray Basics
August 24, 2021
Culture of Food Safety
A Culture of Food Safety with the Right People
June 24, 2021
X-Ray Basics
X-Ray Basics
August 24, 2021
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metal detection or x-ray inspection

The difference between metal detection and x-ray inspection

Metal Detection or X-ray Inspection

metal detection or x-ray inspection

Metal detection (or X-ray inspection) acts as your first defense to identify foreign contaminants in food before they leave the manufacturing facility. Your selection of a system for detection involves quality assurance professionals, process engineers, and corporate safety executives. Together, you make the decision as to which kind of technology will protect a product from foreign contaminants. Most often, three criteria will the best detection point (hopefully near the center of the aperture), the application capability, and the cost-to-benefit ratio. Still, while these technologies have been used in food manufacturing for decades, hardware and software enhancements continue to develop new standards for quality. At times, this can create confusion about which method will work best for your application.

TYPE AND SIZE

The type and size of contaminant you need to detect (and the speed of the production line) can present a daunting challenge for any system. The challenge in front of you isn’t always finding the contaminant but in ignoring the product effect, the actual packaging, and/or the environment (vibration, radio transmission, etc.). You may have to deal with false positives, and that can add up to lost revenue, so the process requires dependability and consistency. In addition, detection systems in the food industry must be sensitive, operator friendly, as fully automated as possible, and cost effective. Moreover, the system must tolerate whatever conditions surround it, including a hot, moist, dusty, or even freezing environment.

PERFORMANCE

Three things govern performance: contaminant type detectability, smallest contaminant size, and likelihood or probability of detection. At the bottom of this article is a summary of contaminant types by technology as well as a table of densities for a variety of materials. These are only a general guideline. It is possible to miss contaminants or unexpected foreign objects you thought didn’t exist. This is especially true considering that metal detectors will not find anything but metals, and x-ray systems will rarely detect smaller size plastics or other contaminant types. As a general rule, x-ray systems will not find contaminants that float in water (like wood).

With X-Ray, you may find it works best to test many samples with different contaminants. At Testrods.com we designed a thermoform multi-card specifically for this purpose. You can choose from 10 different contaminant types including: Ferrous, Non-Ferrous (Brass), Stainless Steel 316, Aluminum, Soda-Lime Glass, Ceramic ZR02 and AL203, PTFE (Teflon), Acetal (Delrin), and Rubber in a wide variety of sizes. We can place as many different types and sizes on a single card as you need. That way, you can look at a single image and determine what types and sizes you can achieve. Once you know the capabilities of your system, you can purchase single contaminant cards for regular testing during production.

As an additional note, we have even developed a bone simulate card using precision cut aluminum. Using a multi-card for bone simulate, you can easily compare the bone you’re looking for against the various sizes of aluminum. Then, you can purchase single contaminant cards for regular testing during production. Call 866-977-8663 or email brian@regalpack.com for more information about multi-cards.

DETECTION

We define the probability of detection as the chance of missing a contaminant while producing real products at normal speed. Of course, the bigger the contaminant, the better the chance of detection. A Hazard Analysis and Critical Control Point (HACCP) plan should design and document management of the food safety process. Hazard Analysis determines which contaminant issues will occur. The Critical Control Point can appear in multiple places, so you need to examine the entire line for potential danger. Limiting or eliminating problems early in the process diminishes the cost of a product rework. You should never need to scrap an end-product to make the marketplace safe.

Ultimately, all these things will determine the best technology for your product. But it will also include: the type and size of contaminant, the speed of production, the type of product, the container/packaging, and the demands of the various CCPs. Make sure to educate and train your employees to think critically about all these variables, and then build a culture of food safety. Finally, make sure you have the best testing equipment at hand. Call us at 866-691-8560 or email testrods@testrod.com and let us answer any questions you might have. As a general guideline for metal detection or x-ray inspection, use the following breakdown.

Contaminant Type                             Met Det                    X-Ray
  • Metal – Ferrous                    X                         X
  • Metal Non-Ferrous               X                         X
  • Stainless Steel                      X                         X
  • Aluminum                              X                         X
  • Wire                                        X*                       X*
  • Ceramic                                                             X
  • Glass                                                                  X
  • Rock                                                                   X**
  • Bone                                                                   X***
  • Plastic                                                                X
  • Wood, pits, shells,  insects, etc.                     ****

* Dependent on orientation

** Dependent on type and size

*** Only calcified bone and still very difficult based on animal type, age, etc.

**** Not conductive for MD or typically not dense enough for X-Ray

DENSITIES
  • Polyethylene                      0.857 g/cm3
  • Polyvinyl                             0.892 g/cm3
  • UHMW                                0.931 g/cm3
  • Water                                  1.0 g/cm3
  • Rubber                                1.2 g/cm3
  • PETG                                   1.38 g/cm³
  • Acetal (Delrin)                   1.4 g/cm3
  • PTFE                                   2.2 g/cm3
  • Borosilicate                       2.23 g/cm3
  • Soda-Lime Glass              2.5 g/cm3
  • Aluminum                          2.7 g/cm3
  • Ceramic (AL203)              3.7 g/cm3
  • Ceramic (ZRO2)               5.6 g/cm3
  • Stainless Steel 316         7.82 g/cm3
  • Ferrous                             7.85 g/cm3
  • Non-Ferrous                    8.48 g/cm3

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2 Comments

  1. Eli Richardson says:
    December 7, 2023 at 1:26 pm

    It’s interesting to know what type of contaminants an X-ray and a metal detector can identify. My dad’s been on the edge of a lawsuit ever since a client got injured eating their food products. I think my dad should implement strict detection solutions this month, so I’ll email your insight to him now.

    Reply
    • brian says:
      December 7, 2023 at 1:34 pm

      Glad to be of service. I hope your dad benefits and also that his dispute with the customer is able to be resolved.

      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.