Metal detectors: How to protect yourself from product recalls The detection and rejection of metal contaminants is used in various applications, including the food, pet food and pharmaceutical industries.

Manufacturing companies that opt for metal detection benefit in many ways. First and foremost is the assurance of product quality and thus the protection of consumers. Contaminated products can lead to expensive recalls and brand damage.

The position of the control point is crucial for successful metal detection. If the metal detection is used, for example, in front of cutters or grinders, expensive repairs as well as the crushing and multiplication of foreign bodies can be prevented. Another metal detector upstream of the packaging line ensures a final check of the products - also for metal parts that may result from the production process . In this way, our metal detectors support compliance with industry regulations such as HACCP, IFS and BRC.

High-precision metal detectors for reliable foreign object detection

We offer a wide product portfolio of metal detectors. In order to select the right metal detector, various conditions must be taken into account. For example, will the metal detector be exposed to frequent and intensive cleaning procedures? Then it makes sense to choose a correspondingly high IP protection class. Or are there in the environment flammable substances? Then the metal detector should have ATEX certification, i.e. an explosion protection class.

After you have examined the environmental conditions in which your metal detector will be used, consider the product sizes and determine the channel openings accordingly. The smaller the ratio of product size to channel opening, the higher the sensitivity. A ratio of about 70 percent is considered ideal. In the last step, the nature of your product plays a decisive role. With our search coils, free-fall or pipe metal detectors,we have the ideal solution for every product type. Even with large product effects, i.e. products with high conductivity, we offer high-precision metal detection solutions.

Your advantages from our metal detection technology

✔ Product safety

✔ Increased efficiency due to fewer false rejects

✔ Compliance

✔ Protection of brand integrity

✔ Customer satisfaction

✔ Injury prevention

✔ Protection of production facilities

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Reduce false rejects with MiWave modulation

Products with high conductivity pose major challenges for today's metal detectors and significantly reduce the achievable search sensitivities. We cite the flexible MiWave modulation as an innovative technology here. A process that modulates a multitude of frequencies onto the transmitted signal, then separates them and evaluates them separately using an intelligent algorithm. By splitting the signal into several signals, the products can be inspected from several perspectives. Due to this significantly increased information content, high search sensitivities can be achieved despite large product effects.

If you are looking for a metal detector for applications in the food industry and have decided on MiWave technology, then our Mitus® metal detector is exactly what you need. If your application does not require the use of MiWave technology, we recommend our Vistus® metal detector.

Mitus® metal detection system

Reliable inspection for demanding applications

  • Highest detection sensitivity for foreign bodies in production lines of the food industry
  • MiWave technology tolerates fluctuations in product effects
  • High ease of use, optimal connectivity and different design variants
  • Durable, robust design

Vistus® metal detection system

Reliable inspection for common applications

  • High detection sensitivity for foreign bodies in production lines of the food industry
  • Wide frequency spectrum for maximum detection performance
  • High ease of use, optimal connectivity and different design variants
  • Durable, robust design

No matter whether you have chosen the Mitus® or Vistus® metal detectors: Both solutions can be can be integrated one-to-one into our search belts free-fall or pipeline systems.

Our metal detection belt solutions for packaged products

The Free fall is the first choice in metal detection solutions for Food in powder or granular form that are transported through a pipe by gravity

The pipeline detects and removes metallic Impurities in pumped viscose or liquid products.

Product videos

Metal Detector Mitus®

Product Video Metal Detector Mitus® with new MiWave Technology

Freefall Metal Detection System Vistus®


The innovative Freefall Metal Detection System Vistus® ensures the reliable elimination of metallic foreign bodies from powders and granules. True In-Process Validation guarantees correct performance validation for maximum product quality and safety.

Metal detection solution to protect your production workers and machines

Our Secus® metal detector offers efficient and effective protection for your machines. It ensures reliable prevention of metallic foreign objects from entering your production process, thus reducing downtime due to repairs to a minimum. At the same time, it ensures the safe working environment of your employees by reliably protecting them from injuries caused by splintering metal parts. Secus® was specially developed for the requirements of heavy industry and impresses with its extraordinary robustness and a detection sensitivity that has been optimised specifically for the needs of the raw materials industry.

Need help configuring your weighing or inspection solution?

Just send us your questions or requests via the contact form or give us a call. We will be happy to help you.

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How does a metal detector work?

Metal detectors have a tunnel-shaped or round opening through which the product is passed horizontally or vertically. The high variety of designs is important because the passage opening and products must be matched to each other.

Detection based on an electromagnetic field

Regardless of the design or area of application, the technology of a metal detector is based on the alternation of an electromagnetic voltage field. To make this possible, the detector contains search and receiver coils, usually made of copper, arranged around the search channel. In simple terms, the metal detector is based on three coils. The middle coil is the so-called transmitter coil. It emits a high-frequency electromagnetic alternating field. The two outer coils are the receiver coils. The receiver coils are mounted in the opposite direction. The evaluation electronics and operating unit (HMI) connected to the transmitter and receiver coils are either integrated in the housing or also designed in a separate terminal, depending on the housing dimensions.

The mode of operation of a metal detector

An optimal evaluation requires a perfectly balanced signal of both receiver coils to each other. In addition to an unchanging distance between the coils, the decisive factors include the search channel and the evaluation electronics. The inductive coupling of the three search coils is the basis of metal detection. The two receiver coils are electrically interconnected in such a way that the voltages induced by the transmitter cancel each other out. If an object is passed through the search tunnel, this results in a change in the magnetic field and thus a voltage difference. Depending on the electrical and magnetic conductivity of the object, this change is of varying magnitude. Because of their properties, metallic materials are particularly suitable for this principle.

Which foreign objects are detected by metal detectors?

Basically, the metal detector detects foreign objects made of metal. This also includes those made of iron, non-iron and non-magnetic stainless steel.

Ferromagnetic metals (Fe)

All metals that are easily attracted by a magnet (e.g. steel). Iron is the easiest metal to detect.

Non-ferromagnetic metals (NonFe)

Non-magnetic metals with a high conductivity (e.g. aluminium). Due to their conductivity, these metals produce a similar signal to iron in dry products.

Non-magnetic stainless steel (SS)

High quality stainless steels from the AISI 300 series (e.g. AISI 304). Because of their low conductivity and permeability, these metals are relatively difficult to detect. A prerequisite for successful detection is that no metallic objects pass through or past the search coil either in the immediate vicinity or on the product packaging itself. A screw can with an aluminium seal, for example, makes reliable detection of metallic foreign objects difficult. For this application, an X-ray inspection system would be the checkpoint of choice.

What does a product recall cost?

Allianz Global Corporate & Specialty had conducted an evaluation of product recalls in the past. In addition to undisclosed allergens and misrepresentations, the following play a role Foreign body contamination plays an overriding role. In the event of significant product recalls, i.e. the product has arrived in the international retail trade, the damage amounts to an average of 8 million euros. In addition to the risk of damaging the image of users, there is also the risk of damage to the image of the company among its trading partners. A product recall can have a negative impact on delivery reliability and thus on the business relationship.

What is the product effect?

As already mentioned, the physical principle of the metal detector is ideally suited for the detection of metallic foreign bodies. However, all materials have specific electrical and magnetic conductivity properties, as does the product under investigation. The effect of these properties is called the product effect. Depending on the nature of the product, this can range from negligibly small to significantly large, which in turn affects the search sensitivity to be achieved.

Salt water, for example, is a very good conductor with a very low permeability compared to metal. As soon as salt water is exposed to an electromagnetic field, eddy currents generate a magnetic field. If the product effect generated by the product is large enough to cause a magnetic field disturbance similar to that of a potential contaminant, the detection result will be inaccurate.

Explanation of terms


Permeability of a material for certain substances (e.g. that of the soil for water).


Conductivity is a quantity in physics. It describes how well a particular material conducts the electric current.

Further information

Learn more in our White Paper "Metal detection in production lines: Requirements, technology and application recommendations" for more details on metal detection.

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We provide a guide for selecting the correct metal detection technology with our How to Guide "Foreign bodies always one wavelength ahead: How you as a food manufacturer can choose the right metal detection technology".

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