A key element of the food industry is upholding essential safety standards. Before packaged food reaches consumers, it goes through a series of safety checks to ensure it is fit for consumption. Industrial metal detectors play a vital role in this sector, as metal is one of the most frequently occurring contaminants in food processing. This article explores the reasons for using metal detectors for food industry, how they work, and the contexts in which they are most beneficial.

Why is Metal Detection Essential in the Food Industry?

Metal is a common contaminant in food products. It can enter food at any stage of processing because most machinery used in food production is made of metal.

Even a tiny part of metal found in processed foods could lead to:

• Large-scale product recalls, which are expensive and damaging to the brand’s reputation
• Harm to consumers who might end up ingesting it
• Legal liabilities and fines for non-compliance

Metal detectors for food industry maintain the integrity of unpackaged, packaged, and bulk goods by effectively identifying and removing metal contaminants.

How Do Metal Detectors for Food Industry Work?

A conventional metal detector used in the food industry uses an electromagnetic field to detect metal in food. Metal creates disruptions in the field. The detector locates them and identifies the type of metal in the food sample.

Here’s how it works:

• A transmitter coil generates the electromagnetic field that surrounds the product.
• The food product moves up on a conveyor leading up to the metal detector.
• Once the product passes through the detector, a receiver coil detects any disruptions in the electromagnetic field and flags it.
• When detected, the contaminated product is removed from the production line.

Modern metal detectors for food industry are often versatile enough to inspect a wide range of product types and packaging formats.

For example, metal detection in loose powders such as spices is often challenging because of the variation in particle size, density, and texture, as well as high dusting, processing volumes, and so on.

In this case, metal detectors can fit into any part of the spice processing chain, identifying metal contaminants during harvesting, production, or packaging.

They can also remove foreign metal objects during sorting and grinding, and inspect sealed and filled packages for any metal.

Types of Contaminants Industrial Metal Detectors can Detect

Primarily, there are three kinds of metal contaminants:

• Ferrous
• Non-ferrous
• Stainless steel

The ability of a metal detector to detect various metallic components depends on its conductivity and magnetic permeability. This means that different kinds of contaminants would behave differently under the detector.

For instance:

• Ferrous metals are easily detected since they are both magnetic and conductive
• Non-ferrous metals are not magnetic, but are good conductors. This helps metal detectors identify them easily.
• Stainless steel is tough to detect because it’s both non-magnetic and a poor conductor. In fact, it becomes trickier to detect when the product is wet or salty.

Metal detectors for food industry can be modified and upgraded to detect the specific contaminants producers wish to detect.

Exceptions

In some cases, food packaged in aluminium foil or trays needs to pass through metal detectors. This can be challenging because, unlike materials like stainless steel, aluminium is a good conductor, which can disrupt the electromagnetic field. 

To address this issue, manufacturers often rely on ferrous in-foil detectors. These detectors switch to a magnetic-only mode, which filters out non-magnetic metals such as aluminium. Manufacturers may also opt to include metal detectors in their upstream line or use X-ray inspection systems for added safety.

Types of metal detectors for food industry

While the core principle of a metal detector remains the same, depending on the manufacturing environments and demands, it comes in different varieties:

Conveyor Metal Detectors: These detectors flag contaminants in free-flowing raw materials that descend along production lines.

Gravity-feed Metal Detectors: For free-flowing raw materials that descend along production lines, these detectors are often used to flag any contaminants.

Pipeline Metal Detectors: For contaminants in liquids, pastes, slurries, and so on. These detectors are integrated directly into the processing line and can detect metal fragments in pumped products.

In addition, manufacturers can use a handheld metal detector for quick spot checks and specific verifications.

Choosing the Right Metal Detector for Your Manufacturing Unit

Different types of metal detectors are suitable for different manufacturing environments. Here are certain parameters to keep in mind when choosing the right kind of metal detector for your shop floor:

Production flow: Choose a metal detector that adapts to the production line’s speed.

Compliance: The preferred metal detector must comply with applicable local and international regulatory standards.

Smooth integration: The metal detector must fit in seamlessly with the production line.

Sensitivity: The preferred detector must be able to detect the contaminant, regardless of size.

Prompt offers the Combi Checkweigher – a highly accurate checkweigher with a metal detector that can identify all three forms of metal contaminants. Its capacity can be tailored to the end product’s weight, accommodating products up to 6 kg. By combining weighing and metal detection, it helps manufacturers meet stringent quality standards for both weighing accuracy and contamination control.

To Conclude

Metal detectors are crucial for food safety, helping eliminate metal-based contaminants. Because they vary in conductivity and placement in the production line, manufacturers can use them to inspect different kinds of products.

Whether inspecting loose raw material or packaged products, metal detectors provide an effective solution for eliminating contaminated food items.

Looking for a Metal Detection Solution?

Prompt Combi Checkweigher helps food manufacturers:

• Detect ferrous, non-ferrous and stainless-steel contaminants
• Verify product weight simultaneously
• Improve compliance with food safety standards
• Reduce manual inspection efforts
• Protect brand reputation

Request a consultation to identify the right inspection solution for your production line.

FAQs