SN04-N2 Proximity Sensor for CNC Limit Switches

The SN04-N2 proximity sensor is a compact inductive switch built to detect metal objects without any physical contact. It suits CNC router and mill builders who need a dependable trigger for limit switches or a home reference point on each axis, and its slim body fits into enclosures where space around the rail is limited.

Because it has no moving parts, the sensor avoids the wear that affects mechanical microswitches over thousands of cycles. Its small cylindrical body fits easily into tight axis carriages, spindle mounts, and gantry ends, so it can be added to an existing build without redesigning the mechanical layout.

Key Features of the SN04-N2 Proximity Sensor

The SN04-N2 proximity sensor uses a threaded metal housing that screws directly into brackets, aluminium profile channels, or custom mounting plates. Two lock nuts let the installer fine-tune the sensing face position relative to the target metal, which matters when setting a repeatable home position on a CNC axis.

The sensing element reacts to a change in its electromagnetic field as a ferrous or metallic target approaches the active face. This non-contact principle keeps the response consistent over long production runs, since there is no physical wear surface to degrade, and the switching point stays stable after repeated homing cycles.

• Cylindrical threaded metal body for bracket or profile mounting
• Non-contact inductive detection of metal targets
• Two mounting nuts for adjustable sensing distance
• Output signal compatible with common CNC controller boards
• No mechanical parts to wear out over repeated cycles
• Compact size for tight axis and gantry mounting points

Where It’s Used

CNC router and mill builders fit the SN04-N2 proximity sensor at the end of X, Y, and Z axis travel to mark the home position during homing cycles. It also works as a physical limit switch, stopping the controller before the gantry or spindle carriage reaches the mechanical end of the rail.

Beyond machine axes, the same sensor design appears in general automation tasks such as counting metal parts on a conveyor or confirming that a metal fixture is seated correctly before a cycle starts. For a wider selection of switches, controllers, and other CNC parts, browse the CNC parts shop.

What to Check Before Buying

Confirm the wiring configuration before ordering, since inductive sensors come in NPN or PNP output types and the wrong one will not communicate correctly with some controller boards. Check the supply voltage range against the power rail already used in the electrical cabinet before wiring the sensor in.

A common installation mistake is mounting the sensor too far from the metal target, so the field never reaches it, or too close, so the target strikes the sensing face during travel. Leave a small, consistent gap and test the trigger point before locking the nuts in place.

Installation and Maintenance

Mount the SN04-N2 proximity sensor through a bracket or aluminium profile slot, then use the two nuts to set the correct distance from the metal target and lock the position. Route the cable away from moving parts and secure it with clips or a cable chain to prevent fatigue from repeated flexing during axis travel.

Because the design has no contact surface, maintenance is limited to keeping the sensing face free of metal dust and swarf, which can interfere with detection accuracy on a busy workshop floor. For background on how inductive sensing works, see the Wikipedia entry on proximity sensors.

FAQ

Does the SN04-N2 proximity sensor need to touch the target? No, it detects metal objects through a change in its electromagnetic field, so a small gap between the sensor and the target is enough.

Can it replace a mechanical limit switch on a CNC axis? Yes, it is commonly used as a limit or home switch since it has no moving parts to wear out over time.

What kind of target does it detect? It responds to metal targets such as steel brackets or plates mounted on the moving axis.