M3 / M4 Non-Threaded (Thread-less) Inductive Proximity Switches

Name: M3 / M4 Non-Threaded (Thread-less) Inductive Proximity Switches
Brand: DAIDISIKE
SKU: m3-m4-non-threaded-inductive-proximity-switches
Availability: InStock

D3/D4mm non-threaded inductive proximity switches for flush-mount metal detection in space-constrained fixtures.

M3 / M4 Non-Threaded (Thread-less) Inductive Proximity Switches - dimensional drawing

🔍 Click to enlarge · 1/9

Technical Specifications

Sensing Method	Inductive
Housing (M3)	Cylindrical M3, non-threaded (thread-less)
Housing (M4)	Cylindrical D4, length 25mm, non-threaded
Output Type	NPN / PNP, normally-open (NO) / normally-closed (NC)
Sensing Distance (M3)	0.6 / 0.8 / 1.0 mm
Sensing Distance (M4)	0.8 / 1.0 / 1.2 / 1.5 mm
Mounting	Flush
Operating Voltage	10-30VDC
Wiring	3-wire (DC)
Response Time	0.1ms - 0.3ms
Switching Frequency	1KHz - 2KHz
Protection Rating	IP67
Operating Temperature	-25°C to +70°C
Short-Circuit Protection	Yes, with 180mA over-current protection point
LED Indicator	Yes
Standard Cable Length	2m (longer lengths available on special request)
Housing Material	Nickel-plated copper
Repeatability	< 3.0% (Sr) / < 5.0% (Sr)
Switching Hysteresis	< 15% (Sr)

Overview

This is a two-size family of DC 3-wire inductive proximity switches: the M3 non-threaded standard type (D3x25mm barrel) and the M4 non-threaded type (D4x25mm barrel). Both are flush-mountable, detect metal targets without contact, and are available in NPN or PNP output with normally-open (NO) or normally-closed (NC) function.

They are intended for machine builders, panel builders, and automation integrators who need a very small-diameter inductive sensor to fit into tight fixture bores, narrow brackets, or compact machine sections where an M8/M12-class threaded sensor is physically too large.

Features & Benefits

Ultra-Small D3/D4mm Barrel for Space-Constrained Mounting

Non-threaded cylindrical housing of just 3mm or 4mm outer diameter lets the sensor fit into fixture holes and narrow slots that standard threaded (M8+) proximity sensors physically cannot enter.

Flush (Embeddable) Mounting

Both M3 and M4 versions are rated for flush mounting, meaning the sensor face can be installed level with the surrounding metal without a clear zone, saving further space in the fixture design.

Configurable Output: NPN/PNP x NO/NC

Each sensing-distance variant is offered in four wiring/logic configurations (NPN-NO, NPN-NC, PNP-NO, PNP-NC), so integrators can match the sensor directly to their PLC input card type and desired logic without external relays.

Multiple Sensing-Distance Options per Size

M3 offers 0.6/0.8/1.0mm sensing distance; M4 offers 0.8/1.0/1.2/1.5mm, giving finer selection to match target size, mounting tolerance, and detection reliability requirements.

Fast Response for High-Speed Counting/Positioning Tasks

Response time of 0.1-0.3ms and switching frequency of 1-2KHz across the D3/D4 non-threaded family support detection of fast-moving or closely-spaced metal targets.

IP67-Rated, Wide Operating Temperature Range

Rated IP67 ingress protection and an operating temperature range of -25C to +70C allow use in washdown, dusty, or outdoor-adjacent industrial environments without a separate protective housing.

Built-In Short-Circuit and Overload Protection

The sensor includes short-circuit protection and an over-current protection point of 180mA, reducing the risk of sensor damage from wiring mistakes or load faults during commissioning.

LED Status Indication for Fast On-Site Diagnosis

A built-in LED indicator shows the switching state, letting technicians visually confirm sensor triggering during installation and troubleshooting without a multimeter.

Applications

Small-Part Presence/Absence Detection on Assembly or Packaging Lines — The 0.6-1.5mm short sensing distance and compact D3/D4 housing suit close-range detection of tightly spaced small workpieces on assembly or packaging lines.

Rotary Index Table / Turntable Position Detection — Flush mounting plus a fast 0.1-0.3ms response support detection of a rotating fixture's position as it passes the sensor at speed.

Metal Can / Container Detection on Production Conveyors — The inductive sensing principle is designed for metal targets, and the short non-contact sensing distance suits close-range placement beside a conveyor line.

Pallet/Carrier Positioning on Conveyor Track Systems — The small housing size allows mounting in narrow track-side spaces to output a carrier-in-position signal on conveyor systems.

Door/Panel Open-Closed State Monitoring on Machine Guarding — Non-contact detection of a metal door or plate lets the sensor be mounted in narrow frame edges or corners to confirm door open/closed state.

PCB or Small Electronic Component Detection in Tight Enclosures — The D3mm ultra-small outer diameter can pass through narrow bores for mounting inside confined equipment spaces to detect metal shielding cans or metal structural parts.

End-of-Travel / Limit Sensing on Compact Linear Actuators — Flush mounting needs no clearance zone, so the sensor can be mounted close against a metal slide rail or slider to detect a travel limit position.

Fixture Clamp/Jig Position Confirmation in Small Tooling — The short 0.6-1.5mm sensing distance and repeatability of less than 3.0%/5.0% Sr suit confirming that a precision fixture or jig has reached its clamped position.

Models & Ordering Information

M3 Non-Threaded Standard Type (10-30VDC, Flush Mount)

M306N1M306P1M306N2M306P2M308N1M308P1M308N2M308P2M310N1M310P1M310N2M310P2

Sensing distance 0.6mm (M306), 0.8mm (M308), 1.0mm (M310); N=NPN, P=PNP; suffix 1=NO, 2=NC.

M4 Non-Threaded Type (D4x25mm)

Ф4N10.8Ф4P10.8Ф4N20.8Ф4P20.8Ф4N110Ф4P110Ф4N210Ф4P210Ф4N112Ф4P112Ф4N212Ф4P212Ф4N115Ф4P115Ф4N215Ф4P215

Sensing distance 0.8mm (0.8), 1.0mm (110), 1.2mm (112), 1.5mm (115); N=NPN, P=PNP; first digit after N/P: 1=NO, 2=NC.

How to Select

Choose the M3 non-threaded standard type when the smallest possible outer diameter is needed for a smaller mounting hole or a more compact fixture.
Choose the M4 non-threaded type when a slightly larger outer diameter is acceptable, still without threads, while gaining a wider range of sensing-distance options.
Pick sensing distance based on target size and mounting tolerance: M3 offers 0.6mm/0.8mm/1.0mm, encoded in the model number (e.g. M306=0.6mm, M308=0.8mm, M310=1.0mm).
For M4, sensing distance is 0.8mm/1.0mm/1.2mm/1.5mm, encoded in the model number (e.g. Ф4N10.8=0.8mm, Ф4N110=1.0mm, Ф4N112=1.2mm, Ф4N115=1.5mm).
Choose output type to match the connected PLC/controller input card: models with "N" in the model number are NPN output; models with "P" are PNP output.
Choose NO or NC logic to match control requirements: model suffix "1" = normally-open (NO, conducts when target detected); suffix "2" = normally-closed (NC, opens when target detected).
Confirm the wiring is 3-wire DC: brown = positive (+), blue = negative (-), black = signal output line, output connects through the load to the PLC input.
Standard cable length is 2 meters; confirm with the factory if a longer cable is required for your installation.

📘 Need the full method? How to Choose a Proximity Sensor · NPN vs PNP Sensor Outputs Explained

When NOT to specify the M3 — and what to use instead

Installation depths under 25mm

Why not: This series' body length is fixed at 25mm for both M3 and M4 diameters; no shorter body option exists within this specific product.

Use instead: The M3/M4/M5 short-body (15mm) separate-amplifier inductive proximity switch series.

Detecting non-metallic targets

Why not: This is an inductive family, metal-only by sensing principle.

Use instead: The M8 capacitive proximity switch, the smallest-diameter capacitive family currently offered.

Target gaps or mounting tolerances larger than about 1.5mm

Why not: The longest rated sensing distance in this series is 1.5mm (M4); this is a very short-range family.

Use instead: A larger-thread inductive sensor, such as the M8 inductive proximity sensor series, which reaches up to 6mm.

Non-flush or surface-mount installation where the sensing face can't sit level with metal

Why not: Mounting for this series is specified as flush only; no non-flush variant is offered within this product.

Use instead: The M8 inductive proximity sensor series, which offers both flush and non-flush mounting.

Safety-related guarding or interlocks

Why not: No safety rating is claimed for this product.

Use instead: A dedicated safety switch or safety light curtain (DX series).

Specifications we do not publish yet

We only publish a figure once we are confident it is true. The items below are still being validated through further testing and real-world customer feedback, so for now we would rather leave them open than guess. If one of them matters to your design, ask us for the latest validated status.

Non-ferrous metal sensing-distance correction factor
MTBF / rated mechanical and electrical life
Certification marks (CE, UL, etc.)
Cable conductor gauge for the standard 2m cable
Plating thickness / substrate detail beyond "nickel-plated copper"
Vibration and shock resistance rating

Frequently Asked Questions

What is the sensing (detection) distance of the M3 and M4 non-threaded proximity switches?

The M3 non-threaded type offers 0.6mm, 0.8mm, or 1.0mm sensing distance. The M4 non-threaded type (D4x25mm) offers 0.8mm, 1.0mm, 1.2mm, or 1.5mm sensing distance, selectable per model number.

Are these sensors threaded for mounting?

No. Both the M3 and M4 versions in this series have a non-threaded (thread-less), smooth cylindrical housing, designed for flush mounting into a fitted bore or bracket rather than screw-in installation.

What output types are available - NPN or PNP?

Both NPN and PNP DC 3-wire outputs are available for every sensing-distance variant, each further offered in normally-open (NO) or normally-closed (NC) function, giving four logic combinations per size/distance.

What is the operating voltage?

The rated operating voltage listed in the selection table is 10-30VDC. Please confirm the applicable rating with the factory before final design if your application operates near the boundary of this range.

What is the IP rating and operating temperature range?

The series is rated IP67 and has a stated operating temperature range of -25C to +70C.

How fast does the sensor respond, and what is the maximum switching frequency?

Response time is 0.1ms to 0.3ms and switching frequency is 1KHz to 2KHz, varying by sensing-distance variant.

Does the sensor have overload or short-circuit protection?

Yes. The series includes short-circuit protection and an over-current protection point of 180mA.

What is the housing material?

The selection table lists the housing material as nickel-plated copper.

Does the sensor include a status LED?

Yes, both the M3 and M4 non-threaded versions include a built-in LED indicator for switching-state confirmation, shown in the dimension drawings.

What is the standard cable length, and can it be customized?

The standard cable length is 2 meters. Longer cable can be supplied on special request; please confirm the specific extended-length options with the factory for your required length.

Can you provide certification documents for this sensor?

Certification documents are available on request.