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M3M4 Ultra-Small Inductive Proximity Sensor

DAIDISIKE M3M4 ultra-small inductive proximity sensor — overview

The M3M4 Ultra-Small Inductive Proximity Sensor is a DC 3-wire metal-detection switch designed for industrial automation, with a compact size (M4 × 25 flush mounting) and precise 1 mm detection distance, supporting NPN / PNP outputs. CE and RoHS certified, it offers reliable non-contact metal sensing for space-constrained environments.

M4 × 25 flush1 mm precision sensingNPN / PNP · NO / NCDC 10 – 30 V1000 Hz responseIP65 / IP67CE · RoHS
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DAIDISIKE M3M4 inductive proximity switch — feature illustration

Product Description

The M3M4 Ultra-Small Inductive Proximity Sensor is a high-performance metal-detection switch designed for industrial automation, featuring a DC 3-wire configuration with NPN or PNP output and a compact M4 × 25 (flush) design. With its 1 mm precise detection distance and durable nickel-plated brass housing, it is ideal for space-constrained industrial environments. The sensor includes an LED indicator for real-time detection feedback, making it easy to monitor and integrate into various automation systems. It complies with CE and RoHS certifications, ensuring high quality and environmental standards.

Product Specifications

ParameterDescription
ModelM3M4 (Flush)
Detection distance1 mm ± 10 %
Operating voltageDC 10 – 30 V
Output typeNPN / PNP (NO / NC optional)
Load current≤ 150 mA
Operating frequency1 kHz
Protection ratingIP65
Operating temperature−25 °C to +70 °C
Housing materialNickel-plated brass
Cable length2 m (customizable)
CertificationsCE · RoHS

Model Specifications — 8 Variants

ModelOutputDetectionMountDimensionsVoltageLoadResponseIPTemp.HousingCableCert.Notes
LJ4A3-1-Z/BYPNP NO1 mm ± 10 %FlushM4 × 25DC 10-30 V≤ 150 mA1000 HzIP67−25 °C ~ +70 °CStainless steel2 m PVCCE · RoHSStandard, high sensitivity
LJ4A3-1-Z/AXNPN NC1 mm ± 10 %FlushM4 × 25DC 10-30 V≤ 150 mA1000 HzIP67−25 °C ~ +70 °CStainless steel2 m PVCCE · RoHSHigh stability, harsh environments
LJ4A3-0.8-Z/BYPNP NO0.8 mm ± 10 %FlushM4 × 25DC 10-30 V≤ 100 mA500 HzIP67−25 °C ~ +70 °CNickel-plated brass2 m PVCCE · RoHSMicro detection, precision applications
LJ4A3-1-Z/EXDC 2-wire NO1 mm ± 10 %FlushM4 × 25DC 12-24 V≤ 150 mA1000 HzIP68−25 °C ~ +70 °CStainless steel2 m PVCCE · RoHSCustom voltage, multi-system compatible
LR04-01N1NPN NO1 mm ± 10 %FlushM4 × 25DC 10-30 V≤ 150 mA1000 HzIP67−25 °C ~ +70 °CStainless steel2 m PVCCEIndustrial grade, non-contact
LR04-01N2NPN NC1 mm ± 10 %FlushM4 × 25DC 10-30 V≤ 150 mA1000 HzIP67−25 °C ~ +70 °CStainless steel2 m PVCCECompact design, easy integration
EB-M4-NONPN NO0 – 2 mmFlushM4 × 25DC 12-24 V≤ 150 mA500 HzIP68−25 °C ~ +70 °CMetal cylindrical2 mCE · RoHSAuto-type, shielded / non-shielded optional
EB-M4-NCNPN NC0 – 2 mmFlushM4 × 25DC 12-24 V≤ 150 mA500 HzIP68−25 °C ~ +70 °CMetal cylindrical2 mCE · RoHSHigh response frequency, durable

Application Environments

The M3M4 proximity sensor is suitable for various industrial automation scenarios, including but not limited to:

With an IP65 protection rating, the sensor operates reliably in temperatures from −25 °C to +70 °C, suitable for harsh environments with moisture, dust or high temperatures.

Working Principle

The inductive proximity sensor generates an electromagnetic field from its front end. When a metal object enters this field, it alters the inductance of the sensor's coil. This change is detected by the internal circuit, which converts it into an electrical signal to trigger the switch output (normally open or normally closed).

The M3M4 sensor uses a DC 3-wire configuration (brown = power positive, blue = power negative, black = signal output), providing reliable signal feedback via NPN or PNP output. It detects metal targets without physical contact, offering high sensitivity and fast response for precision industrial applications.

Frequently Asked Questions

What sensing distance does the M3M4 ultra-small proximity sensor have?

The M3M4 has a rated sensing distance (Sn) of about 1 mm ± 10 % for a standard mild-steel target, with a 0.8 mm micro-detection variant. Because it is a flush (shielded) M4 × 25 sensor, non-ferrous targets such as aluminium, brass or stainless steel reduce the range by a known correction factor, so size the target accordingly.

Should I choose NPN or PNP, NO or NC output for the M3M4?

PNP (sourcing) is the default for most modern PLCs, especially in Europe, while NPN (sinking) is common in many Asian control systems. NO closes the output on metal detection and NC opens it. The M3M4 is a DC 3-wire sensor (brown +, blue −, black signal) offered in NPN/PNP and NO/NC, plus a DC 2-wire variant.

Can the M3M4 replace an Omron, Balluff or Autonics M4 proximity sensor?

Usually yes. It shares the M4 × 25 flush thread, DC 3-wire NPN/PNP wiring, IP67 rating and roughly 1 mm sensing distance, so it fits the same bracket and cable run. Match the output type (NPN/PNP, NO/NC), detection distance and housing material to the unit being replaced for a drop-in swap.

What ingress protection and temperature range does the M3M4 offer?

Standard models are rated IP65/IP67, with IP68 variants for submerged or wash-down use. The housing is stainless steel or nickel-plated brass, and the operating range is −25 °C to +70 °C. This makes the M3M4 suitable for machine tools, 3D printers, conveyors and robotics exposed to moisture, dust or vibration.

Why use an ultra-small M3/M4 sensor instead of a larger M8 or M12?

The M4 × 25 body fits where M8 or M12 sensors cannot — tight fixtures, robot end effectors, small jigs and precision positioning. It trades a longer range for compactness, delivering a precise 1 mm detection distance and 1 kHz response. Choose M3M4 for space-constrained metal detection; step up to M8/M12 when you need more range.

Specs reviewed by Engineer Cai, Senior Application Engineer. CE & RoHS compliant — see certificates.