Tunnel detectors
The most widely used arrangement in food production. Product passes through a rectangular aperture on a belt, and contaminated packs are removed automatically. Available as a detector head for a conveyor you already run, or as a complete machine.
607 — 30 kHz608 — 300 kHzIP68 / IP69KPacked and unpacked
With conveyor, or detector head only
Same detection electronics, same enclosure, two very different installation jobs. Which one is right depends on what you already have in the line.
Tunnel detector with conveyor
Detector, belt, frame, controls and automatic reject delivered as one machine. You place it in the line, connect power and air, and it runs.
- Belt height matched to the adjacent equipment
- Reject system, lockable bin and confirmation sensors included
- One supplier responsible for the whole thing working together
- Options: centre-drive motor, side guides, speed control, curved belt, small roller diameter for short products
Choose this when you are building a new line, have no conveyor to break into, or want the reject and its safety chain specified as one package.
Tunnel detector without conveyor
The detector head on its own, for mounting into a conveyor you already have — or into a machine you are building yourself.
- Aperture built to your product's largest dimensions
- Interface drawings and electrical specifications supplied up front
- You keep control of belt type, speed and layout
- Suitable for OEM integration by machine builders
Choose this when the existing conveyor works, space is tight, or you are an integrator building the line around it.
Not sure which? Send us the line height of the equipment either side and a photo of where it has to go. We will tell you which is cheaper to install — that is usually the deciding factor rather than the machine price.
The aperture should be as small as the product allows
This is the single most important decision. Sensitivity is tied directly to aperture size: the bigger the opening, the further the coil sits from product in the centre, and the worse the detection. Measure the product's largest height and width, add the clearance you genuinely need, and go no bigger.
Height matters more than width. An aperture 100 mm taller than necessary costs real sensitivity every day for the life of the machine.
Built to supermarket specification
Major retailers require a chain of surveillance features around the reject, not just the detection. Our tunnel systems can be supplied with the full set:
- Automatic reject system
- Reject confirmation facility
- Bin full sensor
- Lockable reject bin
- Low air pressure sensor
- Back-up sensor
- Alarm for bin door
- Reset switch
| Lamp | Meaning |
|---|---|
| Green | System OK |
| Orange | Bin is full |
| Red | Reject confirmation failure |
| Blue | Low air pressure |
| Detection platform | 607 low frequency (30 kHz) or 608 high frequency (300 kHz), selected by product |
|---|---|
| Construction | Stainless steel, hygienic design, adjustable feet |
| Ingress protection | IP68 / IP69K versions available for full washdown |
| Aperture size | Built to the product's largest dimensions — On request |
| Supplied as | Detector head only, or complete unit with conveyor and reject |
| Reject options | Pusher, air blast, drop flap, retracting belt or belt stop with alarm |
| Reject confirmation | Sensors confirming the pack was actually removed — required where the detector is a CCP |
| Conveyor options | Centre-drive motor, side guides, speed control, curved belt, small roller diameter |
| Connectivity | Ethernet for log access from a PC on the local network. Remote control available |
| Interface | Touchscreen with product programmes, password protection and multilanguage operation |
| Sensitivity | Established by test on the actual product. Book a product test |
We deliberately do not publish one sensitivity figure for the machine. The number is only valid for the product, packaging and temperature it was measured on.
Signal output to bagger or filler
On vertical form-fill-seal lines the detector can signal the bagger not to cut the bag when metal is found. The result is two connected bags, which makes the contaminated portion immediately visible to the operator rather than disappearing into a bin.
Related
Conveyors and convergers — including converger systems that merge product from a thermoformer into a single lane, which raises the achievable detection level compared with inspecting three products side by side.
Checkweighers — if weight control is needed at the same point in the line.
Our unique Service Exchange Concept keeps the line running. If an electrical fault occurs, the complete control unit can be swapped in under three minutes. You get a replacement unit immediately and return the faulty one to us for analysis and repair — so you are not waiting on a repair before you can restart.