Fortress Technology targets hidden metal detection blind spots
Image 1: Seven Fortress Technology Interceptor metal detectors overcome product effect on a grated cheese production line.
Fortress Technology is warning processors that product effect — the natural electrical conductivity of high‑moisture foods — remains one of the most persistent causes of false rejects and missed contaminants on modern production lines.
At the heart of the issue is water. Because water conducts electricity in a similar way to metal, dairy products generate their own signal inside a metal detector’s magnetic field. A dense 20‑kilogram block of Cheddar, for example, behaves very differently from grated mozzarella or a soft cream cheese. This shifting signature can mask or mimic the presence of metal, triggering unnecessary rejects and driving up waste.
Product effect — the natural conductivity of wet, salty or high‑moisture foods — creates a background signal that can overwhelm weaker metal‑contaminant signals.
Aperture size plays a critical role: the larger the product relative to the aperture, the stronger the product effect and the harder it becomes to maintain sensitivity.
Frequency selection is a balancing act. Higher frequencies improve stainless‑steel detection but can worsen product effect on wet products; lower frequencies favour ferrous metals but may miss stainless contaminants.
Software-led approach
Fortress Technology says its latest Interceptor platform is designed specifically to separate these overlapping signals. The system’s adaptive algorithms learn the product’s natural “noise” and distinguish it from the tell‑tale patterns that indicate a contaminant.
Interceptor algorithms analyse multiple signal channels simultaneously, allowing the system to isolate anomalies even when the product effect is strong.
AutoPhase automatically calibrates the detector to each product’s unique characteristics, reducing the need for manual tuning.
M‑phase, developed for large cheese blocks up to 20kg, compensates for the way a single heavy block shifts its signal as it moves through the aperture — a challenge that has historically caused inconsistent performance on bulk dairy formats.
Real‑world deployment: Vepo Cheese
Dutch processor Vepo Cheese recently installed seven incline Interceptor metal detectors across its grated cheese lines. According to the company, the systems have significantly reduced false rejects while improving sensitivity to stainless‑steel fragments — the most common contaminant in dairy processing environments.
Each unit is equipped with integrated data capture, giving Vepo full traceability and audit‑ready reporting. Fortress says this level of digital oversight is becoming essential as dairy manufacturers face tighter retailer specifications and more frequent compliance checks.
