M18 Inductive Proximity Sensor — PNP NPN, OEM China Factory
M18 cylindrical inductive proximity sensor for metal detection in automation, robotics, and machine tools. 5–15 mm flush / 8–23 mm non-flush sensing distance. NPN or PNP output, NO/NC, 10–30 V DC, plus DC 2-wire, AC and AC/DC versions. CE and RoHS certified. SEGMENsensor supplies from OEM volume supply, samples in 5–7 days, production lead time confirmed with the quotation.
CE CertifiedFlush & Non-flushOEM volume supplySince 2019
Key facts
The SEGMENsensor M18 inductive proximity sensor is an 18 mm threaded barrel sensor that detects metal targets without contact and switches an NPN or PNP output. It is rated 5, 8, 12 or 15 mm flush and 8, 16, 20 or 23 mm non-flush on mild steel, runs on 10–30 V DC (NPN/PNP) and fits standard M18 brackets on conveyors, robots and machine tools.
Sensing distance is 5, 8, 12 or 15 mm flush (SGI-GP18S) or 8, 16, 20 or 23 mm non-flush (SGI-GP18U) on mild steel Fe360.
Outputs are NPN or PNP (NO or NC), DC 2-wire, AC 2-wire or AC/DC; the load current is given on the datasheet sent with the quotation.
Connection is a 2 m cable or an M12 connector; the housing is nickel-plated brass, with PBT on some models.
Protection class and operating temperature depend on the part number and are given on the datasheet sent with the quotation; for heat up to +120 °C or +150 °C use the SGI-HT series (see high temperature proximity sensor selection).
Qualification samples are 1–5 pcs, samples ship in 5–7 days and production lead time confirmed with the quotation.
Last updated · SEGMENsensor Engineering Team
Watch: how an inductive proximity sensor works
How an Inductive Proximity Sensor WorksOne-minute animation: oscillator and coil, eddy currents in a metal target, the drop in oscillation amplitude that switches the output, and what sets the switching distance Sn.
How does an inductive sensor detect metal without contact? Inside the sensor, an oscillator drives a coil wound on a ferrite core. It creates a high-frequency magnetic field in front of the sensing face. When a metal target enters the field, eddy currents are induced in the metal. They draw energy from the field, and the oscillation amplitude drops. When the amplitude falls below the threshold, the trigger switches the output, and the LED lights up. The switching distance, Sn, depends on the sensor size and the target material. Mild steel gives the full rated distance. SEGMENsensor inductive sensors: M8 to M30, Sn 1–25 mm. Learn more at segmensensor.com.
NPN vs PNP Sensor Wiring ExplainedOne-minute animation of 3-wire DC sensor wiring: brown +V, blue 0 V, black output; how a PNP output sources and an NPN output sinks current, and how to match the sensor to the PLC input.
NPN or PNP: which sensor do you need? A 3-wire DC sensor has a brown wire for +V, a blue wire for 0 V, and a black wire for the output. A PNP sensor sources current. When it detects the target, the output switches to +24 V, and current flows through the load to 0 V. An NPN sensor sinks current. When it detects the target, the output switches to 0 V. The load sits between +24 V and the output. So match the sensor to the PLC input: PNP for sinking inputs, NPN for sourcing inputs. SEGMENsensor proximity sensors: NPN or PNP, NO or NC. Learn more at segmensensor.com.
What is an M18 Inductive Proximity Sensor?
An M18 inductive proximity sensor is a cylindrical, 18 mm diameter non-contact metal detection sensor. It generates an electromagnetic field; when a ferrous or non-ferrous metal target enters the sensing zone, eddy currents damp the oscillator circuit, triggering an NPN or PNP switching output. M18 is the most widely used size in industrial automation — compatible with standard 18 mm mounting brackets on conveyor systems, robotic end-effectors, and CNC machine tools. SEGMENsensor's SGI-GP18S (flush) and SGI-GP18U (non-flush) families are available in NPN/PNP, NO/NC, DC 2-wire, AC and AC/DC, shielded (5–15 mm) or unshielded (8–23 mm), with nickel-plated brass housing (PBT on some models). CE and RoHS certified. OEM programs, samples 1–5 pcs in 5–7 days and production lead time confirmed with the quotation from our Shenzhen factory.
Specifications
M18 Proximity Sensor Specifications
M18 values from the SEGMENsensor part-number table (SGI-GP18S flush and SGI-GP18U non-flush families). All output types (NPN-NO / NPN-NC / PNP-NO / PNP-NC) available. Long-range, high-temperature, and weld-immune variants on request.
Parameter
Value
Housing Diameter
M18 (18 mm cylindrical)
Sensing Distance (Sn)
5 / 8 / 12 / 15 mm flush (SGI-GP18S); 8 / 16 / 20 / 23 mm non-flush (SGI-GP18U), on mild steel Fe360
Output Type
NPN or PNP (NO / NC), DC 2-wire, AC 2-wire, AC/DC (fixed by the part number)
Supply Voltage
10–30 V DC (NPN/PNP; 5–36 V DC or 10–55 V DC with V36 / V55); 10–60 V DC (DC 2-wire); 20–250 V AC or AC/DC
Output Current, Switching Frequency, IP Rating
Per part number, given on the datasheet sent with the quotation
Housing Material
Nickel-plated brass (PBT on some models)
Cable Length
2 m cable (other lengths on request)
Connector
M12 connector or 2 m cable (fixed by the part number)
Certifications
CE (EMC Directive 2014/30/EU), RoHS 3 (2011/65/EU as amended by (EU) 2015/863)
Per part number, given on the datasheet sent with the quotation
EMC Standard
EN 60947-5-2
Samples
Samples 1–5 pcs for qualification; volume per project
Lead Time
Confirmed with the quotation (standard production); samples 1–5 pcs in 5–7 days; custom OEM confirmed at order
Download the inductive proximity sensor datasheet (PDF)
Overview of all SGI-GP, SGI-FM and SGC-GP part-number families: rated sensing distances, outputs, supply, connection, housing and how to read the part number. No registration required. Each part number also has a one-page PDF on its family page.
Which Inductive Proximity Sensor Size Do You Need? Choose by Thread Size, Mounting and Output
Standard SGI-GP series, 10–30 V DC, 2 m cable. Sensing distances are on mild steel Fe360. Flush (shielded) sensors can be embedded in metal; non-flush (unshielded) sensors reach further but need a metal-free zone around the sensing face. Other cable lengths, M12 connectors and other distances: see the datasheet or send your requirement. All 302 non-flush part numbers, with 16, 20 and 23 mm long-range versions: M18 non-flush inductive proximity sensors.
Replace the contact letter A (normally open) with B for normally closed. Part numbers follow the SEGMENsensor SGI-GP scheme: series, thread, mounting, distance in 0.1 mm, output, contact, connection. For pressure, heat, welding or analog output, see the proximity sensor overview; for embedded mounting see flush-mount inductive sensors. OEM volume supply · samples 5–7 days · reply within 24 h.
Output Selection Guide
M18 Proximity Sensor NPN vs PNP — Which Output to Choose?
Select the correct output type for your PLC or control system. SEGMENsensor supplies all four output combinations with no tooling change.
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NPN (Sinking) Output switches to 0V
Standard in Asian and Chinese industrial automation
Output pin sinks current to GND when target detected
Compatible with Asian PLC digital input cards (sink-type)
3-wire: Brown (+V), Blue (0V), Black (output)
Available as NPN-NO (output LOW = detected) or NPN-NC
The M18 cylindrical form factor is the default mounting standard across these industrial automation sectors.
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Conveyor & Material Handling
Metal part presence detection on conveyor lines, pallet position sensing, and reject diverter confirmation. Standard M18 brackets fit most conveyor frame extrusions.
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CNC Machine Tools
Tool breakage detection, chuck jaw position monitoring, tailstock travel limits, and coolant-proof door interlock sensing in machining centers and turning cells.
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Automotive Assembly
Body-in-white robot cell metal target sensing, fixture clamp confirmation, and transfer line part-present verification in automotive stamping and assembly plants.
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Packaging Machinery
Metal cap and lid detection on filling lines, position sensing on form-fill-seal machines, and jam detection in cartoning and wrapping equipment.
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Robotic End-of-Arm
End-effector metal workpiece gripping confirmation, part-in-gripper detection, and collision avoidance sensing on SCARA and 6-axis robot end-effectors.
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Hydraulic Press
Ram position detection at top and bottom dead center, safety guarding interlock, and die clamping confirmation in hydraulic and mechanical stamping presses.
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Semiconductor Equipment
Wafer carrier FOUP detection and transport interlock sensing — for a stainless steel housing use the SGI-FM all-metal M18 family; cleanroom suitability is confirmed with the quotation.
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Warehouse AGV
Guide rail metal detection, pallet position sensing at loading bays, and docking confirmation on automated guided vehicles and mobile robots (AMR).
Technical specifications, wiring guidance, material compatibility, and OEM sourcing answers for M18 proximity sensors.
What is the sensing distance of an M18 inductive proximity sensor?
SEGMENsensor M18 SGI-GP part numbers are rated 5, 8, 12 or 15 mm when shielded (flush-mount, SGI-GP18S) and 8, 16, 20 or 23 mm when unshielded (non-flush, SGI-GP18U). These values are measured on mild steel (Fe360) targets. On stainless steel, aluminum or copper the sensing distance is reduced; the reduction factors are given on the datasheet sent with the quotation. Always confirm target material when specifying sensing distance.
What is the difference between shielded and unshielded M18 proximity sensors?
Shielded (flush-mount) M18 sensors have a ferrite ring surrounding the sensing coil, which confines the electromagnetic field to the front face. They can be mounted flush with a metal panel without side interference, but have shorter sensing distance (5–15 mm on M18). Unshielded (non-flush) sensors project the field beyond the housing, giving 8–23 mm sensing distance but requiring a clear zone around the sensor body free of metal. Choose shielded for embedded machine mounting; choose unshielded when mounting stand-off on a bracket.
How to wire an M18 NPN NO proximity sensor to a PLC?
Standard 3-wire NPN-NO wiring: Brown wire = +V (10–30V DC positive); Blue wire = 0V (negative/common); Black wire = output (connect to PLC digital input). When the sensor detects a metal target, the black output wire switches to 0V (sinks current). The PLC input reads a LOW signal = target detected. For NPN-NC, the output is normally LOW and goes HIGH when target is present. The maximum load current is given on the datasheet sent with the quotation.
Can M18 proximity sensors detect stainless steel or aluminum?
Yes, but with reduced sensing distance compared with the rated mild steel value; the reduction factor for each metal is given on the datasheet sent with the quotation. For targets in stainless steel, aluminum or copper, specify SEGMENsensor's SGI-FM all-metal family (M18: 5 or 8 mm flush, 8 or 10 mm non-flush, stainless steel housing), or use the unshielded version to gain sensing distance. Always bench-test with the actual target material before finalizing the mounting distance.
What is the IP rating of M18 proximity sensors and can they be used in washdown environments?
The protection class depends on the part number and is given on the datasheet sent with the quotation. General-purpose SGI-GP M18 sensors are for normal machine surroundings such as coolant splash, with a 2 m cable or an M12 connector. For high-pressure cleaning or pressure at the sensing face, see the special-environment proximity sensors (SGI-HP high-pressure series).
What is the weld-immune M18 proximity sensor and where is it used?
Weld-immune M18 proximity sensors (SGI-WR series) have a PTFE-coated brass housing to prevent weld spatter adhesion and are immune to constant and alternating magnetic fields up to 150 mT. They maintain stable switching output during MIG, TIG, and resistance spot welding operations. Essential in automotive body welding cells, stamping press feeds, and metal fabrication robot workcells where standard sensors false-trigger or have their sensing faces blocked by spatter accumulation.
What is the MOQ and lead time for M18 proximity sensors from China?
SEGMENsensor's standard M18 inductive proximity sensors (SGI-GP18S flush and SGI-GP18U non-flush families) have OEM volume supply. Samples of 1–5 pcs ship in 5–7 days. Production lead time for standard configurations is confirmed with the quotation. Custom specifications (cable length, connector type, housing, weld-immune, logo): lead time confirmed at order. Full private-label OEM is quoted on request, OEM volume supply. CE and RoHS documentation included with every shipment. Factory Registration: 91440300MAEUXXQU04.
Are SEGMENsensor M18 proximity sensors CE certified?
Yes. All SEGMENsensor M18 inductive proximity sensors carry CE marking and comply with EMC Directive 2014/30/EU and RoHS 3 (Directive 2011/65/EU as amended by (EU) 2015/863). CE declaration of conformity is provided with every shipment. ISO 9001:2015-certified manufacturing process. For ATEX/IECEx explosive atmosphere applications, specify the ATEX/IECEx variant — available as an option on request; the Ex marking is as stated on the certificate of the specified model.
Can I get qualification samples of M18 proximity sensors before a volume order?
Yes. Qualification samples of 1–5 pcs ship in 5–7 working days so your engineers can test the sensor in the machine. Production lead time and MOQ are confirmed with the quotation.
Can the M18 proximity sensor be customized for my OEM product?
Yes. Output type, cable length, connector, housing and branding can be adapted to your project. Send the part number you are replacing or the target specification and our engineers will reply within 24 hours on working days.
What are the shipping terms for M18 proximity sensors?
Quotations are FOB China. International freight and import duties or taxes are not included and are arranged by the buyer. All orders are paid by 100% T/T prepayment.
What warranty do M18 proximity sensors have?
SEGMENsensor M18 proximity sensors carry a 12-month warranty against manufacturing defects. Contact info@segmensensor.com with the part number and a description of the fault to start a claim.
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Tell us your output type (NPN/PNP), mounting (shielded/unshielded), and target material — we'll send a quote and datasheet within 24 hours.
