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Standard components used for industrial metal detection systems

Aperture         

This is the ‘whole’ through the metal detector.  The opening is sized to allow the product and transportation system to pass freely through the metal detector without touching the inside surface.  This ‘box’ is typically called the sensing head.

 Control unit

The control unit for a metal detector contains the electronics necessary to perform all the ‘metal detection’ functions.  Dependent on the design their all of the electronics are housed in this unit or only the user interface and associated electronics.  Some system integrate the control unit inside the metal detector sensing head making for more compact installation.  It can also be remote and install in an easier to access location such as near an operator station.

Conveying System

The conveying systems can be a standard belt conveyor, pipeline, gravity feed or other methods for transporting product through or passed the sensing head.  Most systems include an integral rejection device to automatically remove contaminated product or stop the production line.

Power Supply 

The power supply unit much like the control unit houses specific electronics for the operation of a metal detector system.  In the power supply (or PSU) you will find connection to the plant electrical system, reject device(s) and control unit.  Some metal detector manufactures integrate this inside the control unit, while others use a separate box.  

Reject Device 

An equally and sometimes overlooked component to every metal detection system is the reject device.  Often this part of the overall system is neglected or poorly tested.  When the metal detector detects tramp metal it is critical that an automatic system (or reject device) remove the contamination from the production line.  Relying on operators to do this undermines the system as a whole and rarely works well.  Typical reject devices include:

  • Flip Gate
  • Retracting Belt
  • Air Blast
  • Drop Nose
  • Kicker
  • Pant Leg
  • Liquid tight diverting value (ball valves)

Search head

The search head contains the transmission coil and receiving coil.  This is where metal detection starts.  Often the required electronics are located inside the search head to amplify the weak signal for processing in the control unit.  The search head is made from aluminum or stainless steel depending on your specific application.  The physical size varies from manufacture and application.