All inductive sensors have the same basic components:
In an inductive proximity sensor, voltage is switched in a coil (1). This creates an electromagnetic field (2) around the face of the sensor. When a metal target (3) moves into the field, eddy currents form in the metal (4). This causes the field to collapse. When the field collapses, the target is sensed.
Benefits and applications:
Basic inductive technology is influenced by the target material. Some are more difficult to detect and the sensor must be moved closer to the target by a correction factor. With a novel, patented coil structure and electronics optimized for noise immunity, ifm has developed the Kplus family of inductive products that sense all metals at the same range – no correction factor!
There are two evaluation coils with a known relative field strength between UR1 and UR2. When a target enters the field, the factor between the two coils changes and causes the sensor to switch.
Benefits and applications:
With pulse inductive technology, direct current flows through the sensor coil and an electromagnetic field is generated around it. The coil current is switched on and off frequently (induced voltage), so the field builds up and decays on a predictable basis. When a target is present, the decay rate changes and sensor output switches.
Benefits and applications:
This principle uses standard inductive technology, but an embedded magnet allows for the most amount of energy to be transferred to the sensing face. The dampening sleeve focuses the field to very precise switch on and off points. This technology works to detect mild steel targets only.
Benefits and applications:
Sensing range is the mechanical distance where a metal plate approaching the sensor face axially causes the output to switch.
Our datasheets specify 3 different detection distances.
In practice, targets are rarely the standard size and shape used to specify the nominal sensing range. The influence of target size is shown below.
Less common than target size is target shape. The images below show the general influence of shape. It is difficult to provide a correction factor based on shape, so testing should be conducted when the sensing distance is critical.
Finally, the major contributor to sensing range influence is the target material. Materials with less iron form smaller eddy currents and are therefore more difficult to sense. The correction factor by material is shown below.
This correction factor has no influence when using Kplus technology!