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August 27rd, 2023


Snack, bakery, and food-to-go manufacturers are feeling the squeeze from every direction. Stricter processing regulations, faster production loads, escalating operating and ingredient costs, combined with the rise of factory real estate prices, has left many seeking higher throughput, smaller footprint machines. Eric Garr, Regional Sales Manager at Fortress Technology explores the food safety specialists’ approach to “multi-solutions”, shedding light on the pros and pitfalls of implementing these strategies into metal detection and checkweighing lines.  


HACCP states that critical control points (CCPs) are the areas on your production line where hazards can be prevented, eliminated, or reduced to acceptable levels. The first step is identifying your main contamination hazards. For most manufacturers, this will be metal, predominantly stainless steel. Metal is commonly used throughout a production line and in processing and packing environments. Tiny pieces may shred off cutting blades or grinders, faulty packaging machinery might discharge small shards into products, or metal fragments can even be unintentionally introduced further upstream during harvesting.

When assessing risks, the cost of the product at each checkpoint needs to be factored in. For instance, if the only inspection point was located at the end of a production line, any contamination will be caught at the most expensive phase of the production process.

Eric explains: “Ideally you want to catch the metal contaminant in its larger form before it has been processed and packaged, where it could potentially break into many smaller fragments causing many contaminated finished packages. This results in higher quantities of finished product going to waste, and an increased risk of very small, undetectable contaminants reaching the consumer. The most advisable CCPs in the majority of food production environments are before processing, checking incoming raw materials, with an additional inspection system as close as possible to the end of the production line, after primary packaging.”  


Following a risk analysis that determines that metal is your highest contamination risk, the installation of a metal detection system is crucial. So, which one is best? Start by determining the optimum detection frequency for the product application being inspected.

There are generally three metal detection frequency options – fixed frequency, multi-frequency, and simultaneous multi-frequency.

With a single fixed frequency device, the operating frequency is picked to suit the individual product. These fixed frequency devices are ideal when inspecting the same product day in and day out, for example, sliced white bread or a chocolate bar. However, with challenging conductive products like meat or cheese, or a larger product, the frequency must be set low to overcome the product effect. This makes the system less sensitive to the detection of some metals, especially stainless steel.

Conversely, multi-frequency metal detectors perform well on a range of products passing down the production line, as the machine will dial into a pre-defined selection of frequencies. However, not all multi-frequency systems are designed equally.  Some utilize untuned coils where higher power switching devices are used.  This can cause an increase in noise and background signal which can limit sensitivity in high-performance dry product applications. Machine operators on the production line may have to select the frequency from a menu, raising concerns about the basis of their decision-making. Utilizing automatic product learning can reduce the possibility of human error.

Simultaneous multi-frequency delivers a far higher and more sensitive performance on challenging wet product applications that vary in size and conductivity. For example meat cuts, fish, cheese wedges or prepared chilled and frozen meals. Compared to the traditional approach of tuning into specific frequencies, simultaneous multi-frequency technology applied to the Fortress Interceptor range combines the signal from each channel to overcome product effect and improve metal detection performance.


For snack and food-to-go producers especially, high-speed packing, weight and fill systems are essential to generating more products to meet consumer demands. Although throughput determines the cost of production, it’s not purely about speed. Packing and processing lines must also accommodate multiple products in a growing assortment of sizes, packaging, private label and branded products. “This is where flexibility really excels,” notes Eric.

Multi-lane metal detectors, checkweighers and combination systems can cater to these fast product changeovers and support expansion without having to increase physical footprints or employ more people to oversee production. Available in configurations of up to five lanes, the Fortress multi-aperture metal detector or combination metal detector and checkweigher, can provide a smarter and smaller option.

At a time when commercial real estate in North America has doubled in three years, every inch of floor and vertical space carries economic worth. Eric expands: “Often, the under-utilization of vertical and horizontal space which could be making money can be attributed to piecemeal rather than considered machinery investments. Even small changes such as switching out bulky equipment for a combination machine or multi-lane metal detector can add rapid value.”

Singling out and rejecting products from just one conveyor also significantly reduces the volume of good product being wasted. Plus, if one lane requires unplanned downtime or maintenance, the remaining can continue to run. Different products can also be run side-by-side, increasing flexibility for production plants that have multiple SKUs and different product flavors and size variants to inspect.


Food processors are surrounded by immense amounts of data. Keeping track of every metal detection event, such as rejects, performance verification results and any parameter changes, can be especially challenging for production managers.

The processes for extracting and managing data are becoming more streamlined.  With integration of equipment commonplace in production environments, for example with baggers, gravity hoppers and checkweighers, it is now feasible to have a single screen setup. By connecting machinery together, it becomes much easier to gather and consolidate data into a comprehensive performance overview that can help to speed up changeovers.

Generally speaking, it’s more straightforward to integrate a metal detector with existing weighers, baggers and factory management systems, particularly the electronics. Some software integrations can be more seamless than others. It depends on the complexity of the interface technology.


Where there might appear to be a need for multiple machines to cope with the increase in upstream output, Fortress recommends closely examining the options. Ask multiple questions. For example, could a multi-lane system offer a better return on investment in a smaller footprint? Is it possible to channel multiple product lanes through a larger aperture? What sort of reject system is required?

Examine how modular your inspection systems are: Do they provide integration flexibility? Can you extract data and merge this information into a common reporting template? Can you upgrade to newer software?

“It’s always important to really challenge the status quo,” says Eric. “We have reached an era in manufacturing where no processor should ever need to compromise on any performance criteria, including TCO, space and inspection performance.”

Eric concludes “When it comes to innovation, food processors are usually quick to adapt, particularly in relation to business models and systems that boost their governance credentials and lower operating costs. The shifts we witnessed during the pandemic are testament to this. Managed well, multi-functional technology can boost operational effectiveness and elevate your business.”