X-Ray Machines vs Metal Detectors in Food Inspection: A Comparison

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x ray machines and metal detectors

Safety is crucial in the food industry. Contaminants, such as metals, glass, or stones, can harm consumers, damage your production equipment, and destroy your brand. Metal detectors and x-ray machines are the best line of defense in identifying foreign contaminants in food production.

But many companies wonder whether an x-ray machine or metal detector is better. When should companies use both x-rays and metal detectors?

TDI Packsys is proud to be an industry leader in x-ray inspection systems and metal detectors. We provide practical, reliable food inspection technologies and comprehensive support, increasing the safety and quality of your products. In this guide, we’ll outline the benefits of both x-ray systems and metal detectors to explain when to use each type of system.

Do You Need One or Both?

X-ray systems and metal detectors are complementary technologies used in the food industry to detect foreign contaminants. Each technology has its advantages and detects different types of pollutants. Depending on the pollutants you are at risk for, either one or both systems are necessary.

The materials found in the product packaging and the contaminant affect how a metal detector works. In contrast, the shape of a product and the type of transport system used in production affects the success of an x-ray inspection system.

X-ray systems cannot identify a difference in density in free-falling production lines, which rules them out in many bagging systems, such as nuts packaging. Metal detectors, on the other hand, cannot detect glass, bone, or stone. Your needs determine which inspection system—or systems—is the right choice for your production.

Benefits of a Metal Detector

food metal detector in a company

Metal detectors identify contaminants by detecting a disturbance in a balanced electromagnetic field.

The most common metal detectors use a balanced, three-coil system wound on a nonmetallic frame. The center coil connects to a high-frequency radio transmitter, and each receiver coil connects to the transmitter coil.

Due to their identical design and placement, the coils receive the same signal and produce the same output voltage. If the coils connect in opposition, the output is canceled, resulting in a zero value, but when a metal particle passes through one of the coils, the high-frequency field changes and alters the voltage. The coils have lost balance, and the output is no longer zero.

New metal detectors have an extremely sensitive detection system, which significantly improves over previous models. The new generation of metal detection systems takes the technology a step further. They use a specially designed multi-coil. Multiple transmit coils yield a more effective magnetic field for better detection rates.

Companies can use metal detectors on most consumable products, such as:

  •         Bakery items
  •         Meat and sausage
  •         Fruits and vegetables
  •         Dairy products
  •         Spices and sugar

The benefits of this technology are extensive.

  1. Metal Detectors Are Less Expensive

Metal detectors generally require lower up-front costs. The larger the area an x-ray machine has to cover, the more expensive it is. But a metal detector’s price does not change dramatically. The price difference in metal detectors vs. x-ray machines decreases exponentially in large production lines or when requiring a larger aperture for the product inspection.

Metal detectors require less energy consumption, which also drives down costs. These inspection systems can withstand a wide range of environments, from extreme heat to extreme cold, without increasing energy consumption.

X-ray systems require annual inspections from the Radiation Protection Advisor, which also drives up the cost. Metal detectors also consist of fewer parts at risk of damage and which would require replacing. In addition, metal detectors last two to five times longer than x-ray systems.

  1. Metal Detectors Find Aluminum and Metal Contaminants

Metal detectors can identify all types of metal by their electromagnetic field, while x-ray inspection systems depend on density differentials. So, x-ray machines cannot detect aluminum, foil, or metalized film, while metal detectors can.

  1. Metal Detectors Are Well-Suited for Small Spaces and High-speed Production Lines

X-ray systems cannot detect a difference in density if an object travels fast through the conveyor line or in a production that uses gravity falls. Metal detectors, however, can detect metal contaminants in these situations. Metal detectors are also well suited for small spaces.

Benefits of an X-ray Inspection System

can goods going to x ray inspection

An x-ray is a type of electromagnetic radiation. X-rays have a short wavelength, which results in high amounts of energy. This energy allows x-rays to pass through objects. They identify the density of the product and contaminant.

An x-ray traverses the food product, losing some of its energy. A contaminant creates a dense area within the product and reduces the energy allowed to pass through to the x-ray machine’s sensor. The sensor converts the energy into an image of the food product, which helps identify the contaminant.

X-ray inspection systems are safe to use with food products such as:

  •         Harvested goods
  •         Beverages
  •         Bakery Items
  •         Proteins
  •         Frozen foods

This technology has many benefits to a food production system.

  1. X-Ray Systems Detect Glass, Ceramic, and Bones

X-ray inspection systems provide detection capabilities on a wider variety of materials. While metal detectors only identify magnetic or ferrous metal contamination, x-ray machines can detect metals, ceramics, glass, stone, calcified bones, and some plastics.

  1. X-Ray Systems Are Not Affected by Product Effects

Metal detectors use conductivity to inspect for pollutants, but natural conductive products can trigger the metal detectors, causing a false positive. The term “product effect” refers to the natural conductivity and its impact on a metal detector system. Red meats, high salt or high-fat products, and products with a lot of moisture produce this effect.

X-ray systems do not mistakenly detect these product effects, so false positives are less common.

  1. X-Ray Systems Use Density Differential to Inspect Products

Companies can use x-ray inspection systems with products that use foil packaging

X-ray machines operate based on density differential. Since aluminum, foil, and metal packaging have low densities, the x-rays can penetrate through them to identify contaminants. X-ray machines work well with any metal in packaging like aluminum cans,  metallic lids, foil wrappers, or the metal twist ties of bread loaves.

  1. X-Ray Systems Check for Missing Materials as a Final Quality Check

X-ray machines can perform other product inspection functions based on the density differential technology. X-ray inspection systems can perform many final quality checks, such as:

  •         Identify missing or broken products
  •         Check the fill level inside the packaging
  •         Inspect seals
  •         Count components

Which Should You Use in the Food Industry?

Both x-rays and metal detectors are safe to use in the food industry. The food industry has employed these detection systems for decades.

X-rays are very safe. The radiation levels are exceptionally low. Ambient x-ray emissions are less than one microsievert per hour, well below FDA standards.

The machine’s hardware and software include extensive safeguards, which constantly monitor its state and prevent accidental emissions due to operator error or system malfunction. After an x-ray inspection, food products are 100% safe to use or consume.

Whether to use a metal detector or an x-ray machine depends on your needs. Budget and production space are common factors, as is the type of contaminant that is most common with your product.

X-ray inspection machines are the best option if your product is prone to non-metal contaminants or if your product’s packaging contains metalized film or aluminum. However, if your product is more likely to contain metals, including aluminum, then a metal detector might be better.

A metal detector is the best solution if you are looking at a reduced budget or space.

When to Use Both?

two operators in a production line

X-ray inspection systems and metal detectors are complementary technologies. Many companies frequently use both at different points of the production process. Sometimes, the best choice is to use both.

Consider using both devices in your production process if you deal with metallic and nonmetallic contaminants. Your inspection process becomes more thorough, making it easier to spot all types of pollutants.

In most instances, the most effective inspection solution combines two or more inspection technologies. Safety is crucial in food products to protect the consumers and your equipment, and having two technologies allows you to be more thorough in your quality assurance.

Where Should You Place X-ray Machines and Metal Detectors?

A metal detector’s primary function is food safety and consumer protection, but protecting production equipment is also a significant benefit.

By locating a metal detector at the beginning of a production line, you can protect your processing equipment from metal contaminants that may trickle in and damage machinery. Metal contaminants can cause havoc on machinery and result in expensive repair costs and a pause in your production of products.

X-rays are crucial in identifying metal and non-metal contaminants. They are also valuable for determining fill levels, spotting broken products, inspecting seals, and counting components. As a result, x-ray inspection systems are a successful final quality check.

You should place metal detectors within any free-falling step of the production, as x-ray machines are incapable of noticing density differential in these processes and thus unable to detect contaminants.

You should place metal detectors at the beginning of the production line, where raw materials first enter, to protect your equipment further down the line from metal contaminants. This placement can offer optimal protection for both consumers and your equipment.

Incorporate x-ray systems at the end of the production line, after final packaging, to take advantage of its quality assurance capabilities. Consider the x-ray system as a fail-safe benefit.

Food inspection technologies employed at the right point on your food production line are crucial to ensure food safety. Both x-rays and metal detectors are critical components of safe and responsible food production. Contact TDI Packsys to learn more about how our food inspection systems can protect consumers, your company, and your brand.

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