Can Inductance Proximity Sensors Detect Magnets Encased in Metal?

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Discussion Overview

The discussion centers on the feasibility of using inductance proximity sensors to detect magnets that are encased in metal. Participants explore the principles of eddy currents and the impact of metal casings on magnetic field detection.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant suggests that eddy currents induced by a current-carrying inductor could be used to detect the position of a magnet enclosed in a metal casing.
  • Another participant raises the concern that the metal casing may shield the magnetic field, indicating that detection might depend on the sensor's sensitivity to any external magnetic field.
  • A third participant reiterates the use of eddy currents and mentions that modern metal detectors utilize resonance coils, implying a potential method for detection.
  • One participant proposes that if the casing is made of non-ferrous materials (like copper or aluminum), it may be possible to sense the magnetic field using reed switches, Hall sensors, or GMR sensors, suggesting practical applications such as measuring fluid levels.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness of detecting magnets within metal casings, with some suggesting potential methods while others highlight limitations due to shielding effects. The discussion remains unresolved regarding the best approach for detection.

Contextual Notes

There are assumptions regarding the types of metal used for casing and the specific sensors employed, which may affect the outcomes discussed. The sensitivity of the sensors and the nature of the magnetic field interactions are also not fully explored.

sensor
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Hi

To detect position of a metal we can use the eddy currents induced by a current carrying inductor. It is described in this link.

http://www.marktec.co.jp/e/product/ndt/ect/principle.html Would this still work if the target is a magnet enclosed in a metal casing. Basically I need to detect the position of a magnet that is enclosed in a metal casing.

Thanks in advance
 
Last edited by a moderator:
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Hi sensor

welcome to PF :)

The metal case is likely to shield the magnetic field. It would probably depend on the sensitivity of the sensor used to if it could detect
any magnetic field that may or may not be outside the metal casing

Others may have more ideas :)

Dave
 
sensor said:
Hi

To detect position of a metal we can use the eddy currents induced by a current carrying inductor. It is described in this link.

http://www.marktec.co.jp/e/product/ndt/ect/principle.html Would this still work if the target is a magnet enclosed in a metal casing. Basically I need to detect the position of a magnet that is enclosed in a metal casing.

Thanks in advance
The system will detect metal casing.
Modern metal detectors (like those on airports) usually use method of resonance coils.
 
Last edited by a moderator:
If you place the magnet in a non-ferrous casing, such as copper, aluminum, titanium etc... Then, you can sense the field created by the magnet by using reed switches, Hall sensors, or GMR sensors.
This is a simple enough trick for measuring fluid levels in a container.
 

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