Metal Detector & Checkweigher Combination Systems

A metal detector for food can detect a wide range of metal contaminants and conductive materials, including both ferrous and nonferrous metals, and some other conductive compounds. Ferrous metals are conductive and contain iron, though many are composed of carbon or other elements combined with iron. The various types of steel are all categorized as ferrous metals.

Ferrous metals are usually magnetic, and more prone to rust than nonferrous metals. Nonferrous metals are composed of elements other than iron, and include aluminum, copper, nickel, tin, brass and zinc. Stainless steel can be detected as well, but with varying levels of sensitivity depending on the stainless steel’s specific composition. 

All of these types of metal can be detected by inline metal detectors. The exact amount of each metal needed to trigger detection depends on the conductivity of the metal, as well as the conductivity and size of the product being inspected. Some metal particles that are highly conductive can be detected by an inline metal detector. 

Almost all types of food and beverage products can be inspected with an inline metal detector, as long as they are not packaged with any metallic material. Harvested goods, snack foods, bakery items, proteins, and frozen foods are all viable to inspect with metal detection. This means that a majority of packaged food products can be inspected with a standard food metal detector. 

However, products that are packaged with metallized foil, in metal containers, or with metallic inserts are not recommended to be inspected with food grade metal detectors. These products will conduct the magnetic field of a metal detector in the same way that an actual contaminant would. This causes either high false-reject rates (of product without contaminants), or significantly reduced sensitivities of true foreign bodies. X-ray inspection systems are the preferred method for inspecting products packaged with metallic elements, as x-ray does not rely on conductivity during inspection.

The term “product effect” describes the natural conductivity of a product, and the impact it has on a metal detector system in food production. Product effect is observed even on products that are known to have no metal bodies in them.

Because metal detectors for food use conductivity to inspect for contaminants, products that are naturally conductive can trigger the metal detector as they pass through. Red meats, products with high salt or fat contents, and products with a lot of moisture all have above average product effects. These products can still be inspected using a metal detector system. However, it is important to select the right system when considering high product effects.

Certain metal detectors use multi-frequency inspection. This allows them to optimize sensitivity even on those more conductive products. RMD Series High-Configuration Metal Detectors from TDI Packsys allow the operator to modify the frequency of inspection, ensuring high-performance inspection with minimal product effect.

In some applications, product effects are simply too high. Even the most sensitive metal detectors might struggle to inspect products with high product effect. For these products, x-ray inspection systems are a perfect solution, as they do not experience product effect, and will not be affected by changes in the product. To determine if your product has a high product effect, receive a free consultation from TDI Packsys.

Both metal detectors and x-rays can be used to inspect for foreign material in food processing. The main difference between metal detectors and x-ray inspection systems is the methodology of how each machine inspects for foreign materials.

Metal detection uses conductivity to locate stainless steel, ferrous, and nonferrous metals in product. X-ray inspection uses density differences between the product and foreign bodies, allowing for a far greater range of foreign material detection. X-Rays can be used to find metal, glass, stone, bone, rubber, gasket , plastic, and various other mid- and high-density items.

Some products are limited to certain inspection systems due to their composition and packaging. Products with metallic packaging, such as those with metallized foil, cannot be accurately inspected with a metal detector, and require the use of an x-ray inspection system.

The best way to determine which option is best for your application is to receive a consultation or free, no obligation validation testing. We can test your exact product on a variety of different systems using certified test cards, or foreign material samples you provide, to offer you a formal report on the capabilities and expected performance of each type of technology. The validation report is an easy way to test x-ray, without having to purchase or rent.

At TDI Packsys, we believe validation testing on your specific products is an integral step in choosing the right system for your needs.

Many products can be inspected by both x-ray and metal detection. For these cases, which system to use is decided by other factors. Things like budget, sensitivity levels, and customer requirements might all play a role in selection of inspection systems.