Inductive Proximity Sensor
Detects metallic targets without contact by sensing changes in an electromagnetic field.
Use this when…
- Confirming a metal part is seated in a fixture
- Detecting cam or gear tooth position for shaft feedback
- Counting metal objects on a conveyor
Automotive stamping
Inductive proximity sensors confirm steel blanks are seated correctly before a press descends, preventing tooling damage.
Machine tool
Shielded prox sensors detect the home position of CNC axes, providing repeatable reference points for every cycle.
An inductive proximity sensor detects metallic objects without physical contact. Inside the sensing face is an oscillator coil that generates a high-frequency electromagnetic field. When a conductive target enters this field, eddy currents are induced in the metal, which damps the oscillator. The sensor's electronics detect this change and switch the output.
Sensing range depends on the target material. Mild steel gives the full rated range; aluminium and stainless steel reduce effective range by 30-50% due to their lower magnetic permeability. The manufacturer's datasheet always specifies a correction factor.
Shielded (flush-mountable) sensors contain the electromagnetic field within the face, allowing flush installation in a metal bracket. Unshielded sensors project a wider field and offer longer range, but require a metal-free zone around the sensing face.
Output wiring follows the same NPN/PNP conventions as photoeyes. Most industrial sensors are 3-wire: positive supply, negative/common, and signal. The signal wire connects to the PLC input.
Inductive prox sensors are the workhorse of factory automation — rugged, tolerant of oil and coolant, and immune to ambient light. They are not suitable for non-metallic targets; for plastics or liquids, a capacitive proximity sensor is the right choice.
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