Pepperl+Fuchs Blog

Mounting Conditions for Inductive Proximity Sensors

Posted by David Rubinski on Thu, Jul 26, 2012

Part two of two:  How to mount the different sensor types (embeddable, non-embeddable, quasi-embeddable)

In our previous blog post on this topic, we took a look at the different sensor types and their definitions.  Now we'll deal with the preferred methods for mounting each type.

Mounting conditions

Shielded sensors

Because their construction limits the electromagnetic flux path, shielded sensors allow the user to mount the sensor flush with the mounting surface. For cylindrical sensors, this means having the mounting surface even with the sensing face; for cubical sensors the mounting surface can extend up to the face of the sensor.

Note: For cubical sensors the mounting, metal-free zone includes the area on all sides of the sensor.

Embeddable sensor mounting conditions

Mounting metal must not extend beyond the sensing face or pre-damping of the sensor will occur.

  • Cylindrical sensor face must not be recessed into metal
  • Cubical sensor must not have metal beyond sensing face of on any of the four sides of the device

Shielded sensor mounting conditions
Unshielded sensors

Because of their construction, unshielded sensors allow the electromagnetic flux path to freely radiate from the coil system area. This requires that strict mounting conditions be observed with regard to metal in the mounting area. For these sensors it means having the mounting surface below or out of the range of the radiated field pattern.

Note: Non-flush mount sensors are very sensitive to the metal near the sensor mounting zone because as stated earlier, the flux density is highest near the coil system.

Non-embeddable sensor mounting conditions

  • Mounting metal or mounting fasteners must not be in the metal-free zone
  • For cylindrical, unshielded sensors the typical metal-free zone extends to an area of two times the sensing range of the device

Shielded sensor semi-embeddable

Note: These sensors provide a longer sensing range with the added benefit of a full sensor housing length providing side impact protection near the sensor face.

Quasi-embeddable or semi-flush mountable

Quasi-embeddable sensor mounting conditions:

Standard embeddable/flush-mount sensors can be mounted so that the sensing face is flush to the mounting surface or fastener nut. Semi-flush mounting requires that the sensor face be extended by a small amount beyond the metal mounting surface or fastener nut as shown below.

Mounting metal or mounting fasteners must not be in the metal-free zone, otherwise pre-damping or sensor activation can occur.

Shielded sensor quasi-embeddable

In conclusion, selection of the appropriate sensor for the application should not only include evaluation of the sensor housing, sensing range, and electrical output type, but consideration should also be given to the mounting environment for the sensor. Always check the appropriate catalog or data sheet when concerned about having mounting-related brackets or other metal in the mounting zone.

Topics: Terminology, Inductive Sensors, Sensor Accessories

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