Tunnel Metal Detectors for Conveyor Systems

Tunnel Metal Detectors Metal separators for conveyor belt systems are devices for detecting the presence of any unwanted metals in a product moving along a conveyor belt. Poorly maintained machines and the normal wear and tear of the production process are just a few of the ways for metal to get into the final product.

In the plastics industry, plastic scrap and regrinds are ground up into small pieces using grinders and recycled to be used over again. When metal pieces enter the grinders during this process, it can cause everything from damage to the grinder blades, to plugged nozzles on the injection machine, production shutdowns, high repair costs, defects in the final product and expensive product recalls. A relaible metal separation system will not only eliminate production shutdowns, but can save you millions in costly product recalls.

How A Tunnel Detector Works

Like most metal detectors, a tunnel detector is made up of a transmitter and a receiver antenna. As metal passes through the electrical field generated by the transmitter the signal picked up by the receiver will change. The electronics of the metal detector analyze the cahnge in the signal and decides if the change is caused by metal or some other reason. If the change is determined to be a result of metal contamination, then the belt will either stop or reverse direction and trigger an alarm. A user will either remove the contaminated product from the conveyor line or an automatic system will remove the product from the line.

Tunnel detectors are best suited for those cases where a higher level of sensitivity is required. Unlike a surface detector, which can't analyse the entire product, a tunnel detector will analyze the entire product. Unfortunately, even while they are more sensitive than surface detectors, they often require you to redesign the conveyor belt. The type of metal detector needed depends on the height of the product to be conveyed and its general shape, and the size and shape of the metal particles that have to be detected. We offer different types of tunnel detectors for various product sizes.

Mpulse TU
Digital Plus TU

Special features

Our tunnel metal separators offer several advanced features to help the metal removal process. 1) They feature a reduction in knock sensitivity caused by production processes and the kinds of materials to be conveyed. 2) Our tunnel detectors are constructed out of sturdy stainless steel housing made of 1.4301. 3) They use fully sealed coils and use a new environmental suppression system that reduces the effect of outside influences on the detection process. 4) Our tunnel detectors are self monitoring, 5) calibration free and 6) offer levels of sensitivity of 1.0 mm from products as high as 100 mm in height. Our tunnel detectors come in a vareity of sizes.


Our tunnel detectors are best suited for those cases where a higher level of sensitivity is required and the product is higher than 50 mm. They are also designed for the rugged and harsh industrial operating condtions found in automobile and tire manufacturing plants.

Contact us today: - Tel: 973.227.0700

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Plastic Process Equipment

Plastic Process Equipment

23 Spielman Road, Fairfield, New Jersey, USA, 07004-6155
Tel: 973.227.0700 ~ Fax: 973.227.7307 ~ Email: