Metal detector sensor

Need sugession of a sensor that detect steel at a sensing range of 40 cm.

This question needs a few more details so we can help you. How big is the target? What is between the target and the sensor. What is going to control the sensor. Voltages etc. A preliminary schematic would be a big help along with links to technical information on all of the hardware devices. FYTI: Inductive proximity sensors can only detect metal targets. They do not detect non-metal targets such as plastic, wood, paper, and ceramic. Unlike photoelectric sensors , this allows a inductive proximity sensors to detect a metal object through opaque plastic.