Technical Blog

Avoiding Confusion between Non Contacting and Non Touching sensors

The terms Non Contacting, True Non Contacting and Non Touching are normally used when describing position sensors and they can cause some confusion. We've created this blog to help avoid the confusion between them.

Non-Contacting Sensors 

This type of unit employs magnetic technology where the actuating arm or shaft of the sensor is mechanically coupled to the part the position of which is being monitored.  Externally this type of unit looks like more conventional potentiometric sensors but internally it uses a magnet and one or  more magnetic sensors (Hall Effect Sensors or chips).  The sensors are normally mounted in an X format relative to each other and the magnet rotates or moves above them but doesn’t actually make physical contact with them.  As the magnet moves its magnetic field impinges on each sensor and produces an electrical output in each one.  In the case of a rotary sensor the relationship of the magnet produces an unambiguous output over all 360 degrees of rotation of the magnet.  This basic signal can be employed o produce an analogue or digital output in a format which can be used to communicate with some form of monitoring or control system.

In a Non Contacting sensor, some form of bearing is required to hold the actuating shaft in position and allow it to turn freely.  Like any mechanical part this will have a finite but limited mechanical life.  The electrical parts are not subject to any wear.  The magnet, bearings and magnetic sensors are all contained within the sensor body.

Non-Touching (True Non Contacting) Sensors

With the Non Touching sensor the magnetic sensors are housed within the sensor body but the magnet is external, so there aren’t any bearings. The magnet is stood off from the sensor body but close enough so that its magnetic field will impinge upon the magnetic sensors in exactly the same way as described above. The advantage of this type of unit is that because there aren’t any integral shafts, seals or bearings there is no mechanical wear.  The strength of the magnet supplied determines the stand off distance between the magnet and the sensor housing. 

Relative advantages and disadvantage of Non Contacting and Non Touching sensors.

The Non Contacting sensor allows for straightforward mechanical fixing and actuation the sensor body is easily clamped and held in position.  Mechanical drive can be achieved by means of proprietary couplings.

The Non Touching sensor is fully sealed but requires more thought in the mounting etc. in order to achieve and maintain proper spacing.

Types of Non-Contacting Sensors We can Supply

We can offer you a wide range of electrical interfaces for your Non Contacting Sensor from 5 volt or 24 volt supply. We also have a wide range of housing configurations available including 13mm up to 91mm depending on application and environment. 

Non Contacting Rotary sensors are self-conditioned so you can take an analogue 0-10, 0-5, 4-20. They can have Incremental pulse SSI PWM interfaces, they can be straight forward analogue sensor, also be incremental encoder and a single turn absolute encoder.

These sensors are predominantly made to order due to technology, the three wire devices and also available as redundant. They have specific programmable angles from 30-360 degree, they can have specific electrical out-put including switching functions and can be redundant sensors.

Industries for Non-Contacting and True Non Touching Rotary Position Sensors.

These sensors are used in many industries including; Mobile vehicle applications, aerospace, automotive test, general machine tool.

If you would like more information on our Non Contacting and Non Touching Rotary position sensors you can view our video from Pat Goodridge below.


You can also see the products we offer on the Non-Contacting section of our website. 

Or, you can contact us using the details above, one of our technical sales engineers will be happy to help.


Article published on: 01/09/2014