Pick a 2026 inductive sensor by closing four decisions in order: housing diameter and thread (M8/M12/M18/M30) for mechanical fit, sensing range Sr with correction factor for the actual target material, output topology (PNP/NPN, NO/NC, complementary, 2-wire) matched to the PLC card, and ingress protection at least one step above the wash-down profile of the line. Sizing off range alone is the most expensive mistake — an 8 mm target on stainless steel only delivers 0.7 × Sr, so a "12 mm" unit like the ifm IGS211 collapses to ~8.4 mm usable distance after the published steel-correction factor of 0.7 [S1].
The bulk of the catalogue is M12-M30 threaded-barrel PNP NO devices with sensing ranges between 1 mm and 40 mm, 10-36 VDC supply, IP65-IP69K housings, and 100-250 mA switching-current ratings. Prices on a single M18 unit in 2026 sit in the EUR 30-90 band at OEM list, and lead time across ifm, Pepperl+Fuchs, Omron, and the Chinese LANBAO/创唯电子 distributor network is largely off-shelf for standard PNP NO units, with non-flush and high-IP69K variants the only notable stock gaps [S1][S3][S4][S5][S6]. For background on how this sensing family sits inside a wider factory-automation stack, see the inductive sensor reference page.
Housing, thread, and mechanical fit
Threaded-barrel formats dominate because they bolt into a drilled hole with two lock nuts and survive vibration better than block-style rectangular housings. The 2026 catalogue is concentrated at four diameters: M8 × 1 (3-wire or 2-wire, typically 1-2 mm range), M12 × 1, M18 × 1 (12 mm range on the ifm IGS211, brass white-bronze housing, PBT sensing face, M8 3-pin gold-plated connector) [S1], and M30 × 1.5 (10 mm flush-mountable range, 230.5 g, brass nickel-plated body on the ifm II5162) [S3]. Cable exit is 2 m PVC on the lower-cost end (4 × 0.34 mm²) and M8/M12 plug on the field-replaceable end, with the M12 A-coded connector carrying the heavier 200 mA load of the small M8 ifm IE9940 two-wire unit [S2].
Flush versus non-flush mounting is a binary mechanical choice. Flush-mountable devices can be sunk into a steel bracket without range loss, which is critical for M8 and M12 footprints where a non-flush install would protrude into the conveyor or pick face. The ifm IE9940 is flush-mountable at 1 mm range, while the IGS211 is non-flush at 12 mm and trades that geometry for an increased sensing range via the M18 barrel [S1][S2]. Weight scales roughly with diameter — 25 g at M8, 53 g at M18, 230 g at M30 — and that mass matters for high-cycle gantries where end-of-arm tooling adds inertia.
Sensing range, target material, and correction factors
The published "sensing range" Sn is the headline number on every datasheet, but the real engineering number is the corrected operating distance for the actual target. Mild steel = 1.0, stainless steel = 0.7, brass = 0.4-0.5, aluminium = 0.3-0.4, copper = 0.2-0.3 — ifm publishes the same table across the IGS211, IE9940, and II5162 with only minor variation [S1][S2][S3]. Apply the factor at design time: a 10 mm Sn on aluminium actually delivers 3-4 mm, and 2 mm on copper. Operating distance (a) is published as 0...0.81 × Sn on the flush-mount II5162 (so 0-8.1 mm) and 0...0.81 × Sn on the non-flush IGS211 (0-9.7 mm) [S1][S3].
Hysteresis of 3-15 % of Sr is the industry default, with the IE9940 dropping to 1-15 % on the low end for precision index-mark sensing, and the IGS211/II5162 holding 3-15 % [S1][S2][S3]. Switch-point drift is bounded at ±10 % of Sr across all three. Real-world consequence: on a vibratory feeder bowl a 12 mm M18 unit will trip over a 1-2 mm band of mechanical chatter, and you derate sensing distance by 20 % to absorb the bounce. The Pepperl+Fuchs NEB20-30GS50-E2-V1 takes the opposite approach — increased 20 mm quasi-flush operating distance with IP68/IP69K sealing, trading range class for sealing class [S6].
Electrical output, supply, and EMC compliance
PNP normally-open is the 2026 default, accounting for the majority of M12-M30 stock, and the ifm IGS211/II5162 both run 10-36 VDC with a 2.5 V max drop, 100-250 mA permanent current rating, and pulsed short-circuit protection [S1][S3]. NPN/PNP auto-detect outputs (ifm IE9940, 5-36 VDC, 2-wire, 200 mA, 4.6 V drop, 2000 Hz switching) cover legacy PLC cards and are also the right pick when cable run is long, because 2-wire technology lets the sensor share a single pair with a load rather than needing three conductors [S2]. Switching frequency divides cleanly: small M8 two-wire units hit 2000 Hz, M18/M30 3-wire DC units sit at 400 Hz, and high-speed PNP blocks reach 5 kHz on specialty lines [S1][S2][S3].
EMC qualification is the line where cheap Asian catalogue units and European OEM units diverge. The ifm IGS211 carries the full EN 61000-4-2 ESD 4 kV CD / 8 kV AD, EN 61000-4-3 HF radiated 10 V/m, EN 61000-4-4 burst 2 kV, EN 61000-4-6 HF conducted 10 V, EN 55011 class B dossier plus UL E174191 Class 2 supply approval [S1]. MTTF data published on the ifm family sits between 1365 years (II5162) and 3367 years (IE9940), giving buyers a 2-3× reliability spread to anchor lifetime-cost calculations on [S2][S3]. LANBAO markets a comparable 5-technology lineup (inductive, photoelectric, capacitive, ultrasonic, magnetic) but does not publish equivalent MTTF or EN 61000-4-x test data on its corporate page [S5].
Ingress protection, temperature, and harsh-environment picks
IP67 is the floor for general factory use; IP68 is required for submerged wash-down food lines and outdoor skids; IP69K (high-pressure, high-temperature jet cleaning) is the spec to write into beverage, pharmaceutical, and dairy spec sheets. The Pepperl+Fuchs NEB20-30GS50-E2-V1 carries IP68 / IP69K with increased sealing and a 20 mm quasi-flush operating distance, positioning it for the most punishing clean-in-place cycles [S6]. Operating temperature splits the market: most units run -25 to +70 °C or -25 to +80 °C, while the Omron E2A-M30KN20-M1-B1 cited through the 创唯电子 catalogue pushes -40 to +70 °C for cold-storage and outdoor rail applications, at 10-32 VDC and M12 4-pin plug [S1][S3][S4].
Material stack is the third durability lever. The 2026 ifm family uses brass white-bronze coated or nickel-plated housings with PBT sensing faces — a chemistry stable to most cutting fluids and detergents, but attacked by concentrated acids and some hot alkalis. Stainless-steel 1.4404 housings appear on premium wash-down lines at roughly 2-3× the brass-housing price.
Phase-out risk, sourcing, and shortlist logic
Phase-out and discontinuation dates are now published in-line on datasheets and must be checked before committing to a long-running series. The ifm II5162 carries a discontinuation date of 2026-03-31 with the II5676 listed as a direct alternative for new designs, while the IE9940 is flagged as a "phase-out article" without a hard cut-off — both are still in the channel but should not anchor a 5-year production run [S2][S3]. This kind of lifecycle visibility is now table-stakes for OEM-grade vendors and is missing from most distributor-only listings.
Shortlist logic for a buyer in 2026: (1) lock diameter and flush/non-flush first, because that drives the bracket design; (2) pick sensing range × correction factor for the real target, not the headline Sn; (3) match output topology to the PLC card (PNP NO for new builds, NPN for legacy Japanese PLCs, 2-wire for retrofits); (4) write the IP and temperature rating as one step above the actual wash-down and thermal profile, not equal to it; (5) confirm phase-out status before approving the BOM. Adjacent spec families to keep on the same drawing set are linear position feedback via linear guide tracks, non-contact displacement sensor heads, and capacitive sensor switches for non-metallic targets — they share the same 10-36 VDC / PNP / IP67 supply-chain and connector logic. For a related perspective on the wider industrial-automation buy, the harmonic reducer selection map walks through comparable lifecycle and standards-discipline decisions. To track going forward, monitor ifm and Pepperl+Fuchs phase-out bulletins each quarter, watch IEC 60947-5-2 alignment on any new EMC claims, and confirm IP69K test certificates on wash-down lines before PO release [S1][S2][S3][S6].