01Engineered solution
A metal detector only works if the conveyor around it stops interfering with it. Metal-free zone conveyors carry product through the detector aperture without fixed or moving metal nearby, then act on what the detector finds.
Metal-free mid-section
02What the zone is
A metal-free zone is the area around the detector where no fixed or moving metal is present. Keeping metal out of that area is what prevents false triggers and lets the detector run at the sensitivity the product actually needs.
The conveyor is built with an engineered plastic mid-section so the belt can pass through the aperture while the frame, drive and fasteners stay outside the zone.
The engineered plastic mid-section is sized to the detector being integrated, so the zone length is set by the detection unit rather than by the conveyor. A compact frame-to-belt width keeps as much of the detector opening usable as possible. Reference the conveyor specification sheet for the remaining detail.
Roarer supplies the conveyor and the metal-free zone built around a detector. The metal detection unit itself is specified and acquired separately, because its sensitivity, aperture and certification requirements are set by the product being inspected.
03Industrial platforms
Both platforms accept a metal-free mid-section. The choice follows product size and the duty of the line rather than the detector.
A low-profile fabric and modular belt platform with a single-piece frame, universal T-slots and a high-speed nose-bar transfer option. Suited to small and medium part handling through inspection.
Available as belted, modular belt or precision move. Chosen where speed, load or belt tracking under tougher conditions matters more than frame height.
Both industrial platforms carry the same tracking and tensioning arrangement, which is what keeps a belt square through a narrow aperture.
04Sanitary platforms
Food inspection usually means the conveyor has to survive cleaning as well as carry product through the aperture.
A 304 stainless frame with an open design and minimal horizontal surfaces, which is also what keeps metal away from the detector. Designed for non-caustic cleaning chemicals.
Continuous TIG-welded 304 stainless with a #4 polish on outside surfaces, a frame with no horizontal surfaces, tip-up tail and tool-less disassembly for cleaning.
Published figures for the sanitary platform most often specified around a detector.
AquaPruf withstands 100–1,500 psi spray and chlorinated solutions. Both use FDA-approved belting and plastic components.
05Acting on a detection
Detection is only half of it. The reject mechanism is chosen by product weight, stability and how much of the flow has to go with it.
A pusher mounted beside the conveyor is actuated when the detector flags a product. The push is timed to the product flow so it arrives as the product does.
A blast of air removes the flagged product instead of a mechanical pusher. Suited to lightweight products that do not need much force to shift.
An arm swings across the belt width to sweep the product off. Used for bulk flow, because it removes a section rather than a single item.
06Specifying
Three things set the conveyor around a detector. Get them wrong and the detector either misses product or stops the line for nothing.
Food inspection carries cleaning standards, so the frame has to be cleanable to the same standard as the rest of the line. That decides stainless grade, frame geometry and whether the belt lifts for cleaning.
The opening has to suit the product. Around 8 in high by 14 in wide is typical, and the conveyor's frame-to-belt width decides how much of that opening is left for product.
Once something is flagged it has to leave the line before it contaminates what follows, which means choosing between a pusher, an air blast or a diverter arm.
Rejected product has to go somewhere controlled. Lockable reject bins, reject systems and networking interfaces for real-time performance data are all part of the same arrangement.
07Around the detector
A metal-free zone usually appears inside a longer arrangement that also has to buffer, route and present product.
Handle overflow and buffer product when the detector or the downstream process pauses the flow.
Route product to the correct lane after inspection, including the reject route.
Bring lines together before or after the inspection point so one detector covers more of the flow.
Meter and space product so it reaches the aperture singly and at a known rate.
Move product between workstations, packing and inspection without manual transfer.
Where the detector, reject station and surrounding equipment do not fit a standard layout.
08Gallery
Detector integrations, metal-free sections and reject stations.
09Frequently asked questions
Belt formats, frame options and what Roarer supplies around the detector.
Yes. Fabric belt and modular belt conveyors are both available for metal detection, in industrial aluminium-frame and sanitary stainless formats.
Straight, curved and Z-frame configurations are available. The metal-free mid-section itself is a straight run, because the detector aperture is, so curves and elevation changes sit before or after the zone.
No. Roarer supplies the conveyor and the metal-free zone built around a specified detector. The detection unit is specified and acquired separately, because its sensitivity and aperture depend on the product being inspected.
Yes. The 2200 Series is a low-profile platform suited to small part handling and precision movement, which makes it the usual choice where the aperture and the product are both small.
By the detection unit. The engineered plastic mid-section is sized to the detector being integrated rather than to a standard length.
10Related solutions
Inspection usually connects to routing, buffering and handling.
Give us the product, the aperture and the cleaning regime, and Roarer can specify the conveyor and the metal-free zone around it.
Discuss your application