Polyoxymethylene (POM) is the default engineering plastic for precision electronic parts where low friction, high stiffness, low moisture uptake and tight dimensional control coexist in one material, supplied commercially as Delrin, Hostaform, Sustarin, Tecaform and other grades [S3].
Electronics is one of seven industrial domains where POM is routinely specified, alongside transport, machinery, food-grade, construction, pharmaceutical and consumer-products applications; within electronics the canonical parts are plugs, switches, insulation pieces, small-motor gears and click mechanisms [S3]. For a baseline on the polymer family itself, see the POM material reference.
Two grades, two behaviour profiles: POM-H vs POM-C
POM is split into a homopolymer (POM-H) and a copolymer (POM-C); POM-H gives higher strength and stiffness, while POM-C gives improved chemical resistance and thermal stability, and the high crystallinity of the family as a whole is what produces the low friction that suits precision mating parts [S3].
Trade names map cleanly onto the two grades: Delrin is the dominant POM-H line from DuPont, while Hostaform (Celanese), Sustarin and Tecaform are widely stocked POM-C grades; both families are used in electronics, but the grade chosen should follow the dominant in-service stress: pure mechanical load and stiffness favour POM-H, while exposure to hot water, detergents or fuel vapours pushes the spec to POM-C [S3].
Why electronics specifically picks POM over ABS and PC
For moving or mating parts, POM wins on tribology: its low coefficient of friction and high wear resistance make gears, detents and cam followers perform consistently over millions of cycles, which is why POM is repeatedly called out for "moving or integrated elements" in electronic assemblies [S4].
For non-moving enclosures and covers, ABS and PC/ABS remain the default because they accept UL94 V-0 flame-retardant grades, hold notched Izod impact in the 150-400 J/m (ABS) and 500-800 J/m (PC) range, and reach HDT @ 1.82 MPa of 80-95°C (ABS) and 130-140°C (PC), so the enclosure job and the mechanism job usually go to different polymers within the same device [S2]. ABS vs PC selection logic for housings is laid out in the electronics-focused ABS vs PC material guide (use the same criteria when screening enclosure candidates); the POM decision starts once the part list includes anything that slides, indexes, detents or latches.
Decision criteria that actually move the spec
Five engineering parameters separate a working POM pick from a return-of-goods incident: (1) tribology (dynamic vs static friction, wear rate against the mating counterface), (2) dimensional stability under humidity (POM sits in the low-moisture-absorption band compared with PA, which is why PA is the typical tube-fitting partner, not the structural core), (3) continuous service temperature ceiling (POM-C roughly 100°C, POM-H roughly 85-90°C continuous; both lower than PC's 130-140°C HDT) [S2][S3], (4) chemical exposure (POM-C survives hot water and many dilute chemicals where POM-H does not) [S3], and (5) flammability rating needed at the wall section (electronics almost always wants UL94 V-0 or V-2 specified up front, not added later).
A second filter is the manufacturing route. POM is normally injection-moulded; in the reference POM Distributor build, the mould tool was machined from AMPCO copper alloy to lift thermal conductivity, cut cooling time and stabilise cycle time, while spring-loaded pogo pins and PA tube fittings were assembled into the part with a dedicated jig for repeatable positioning [S4]. That process note matters for specifiers: tight-tolerance POM features (pogo-pin bores, gear teeth, latch cams) only stay in spec if the mould steel or AMPCO tool is sized to evacuate heat evenly.
Where POM fits, and where it does not
POM is the right call for precision gears, bearings, bushings, couplings, door and latch mechanisms, click systems, valve seats, conveyor rollers and small-motor pinion gears in office, domestic and industrial electronics, plus any sliding or indexing interface that has to feel "premium" over the part's life [S3]. The same source lists food-grade, pharmaceutical and construction uses where the same tribology plus chemical-resistance argument applies, with FDA-grade POM-C grades available for those regulated lines [S3].
POM is the wrong call when the requirement is dominated by high continuous service temperature above roughly 100°C, by optical clarity, by impact performance at very low wall thickness, or by flame retardancy that has to coexist with high HDT; in those cases the enclosure job moves back to PC or PC/ABS (HDT 130-140°C, Izod 500-800 J/m) or to a flame-retardant PA, and POM stays only on the internal mechanism [S2]. POM also burns, so any spec that lists "must self-extinguish in air at the wall section supplied" still needs a FR-grade polymer (typically FR-ABS or FR-PC/ABS) for the housing.
Comparison: POM-H vs POM-C vs ABS vs PC/ABS for electronic parts
Lining the four up against four decision criteria that come up on every electronics RFQ: stiffness and strength, chemical and moisture resistance, HDT @ 1.82 MPa, and flame-retardant grade availability. POM-H leads on raw tensile strength and fatigue, POM-C leads on chemical and hot-water resistance plus thermal stability, ABS/PC/ABS are the only ones in this set with widely stocked UL94 V-0 grades for thin-wall enclosures, and PC tops the HDT chart at 130-140°C versus POM's roughly 85-100°C band [S2][S3]. The practical split inside one device is therefore: PC or PC/ABS for the visible enclosure, POM-C for internal parts that see any humidity or detergent exposure, POM-H for dry precision gears, and PA (often PA66) for tube fittings and snap-fit living hinges that need more toughness than POM offers [S2][S3][S4].
Sourcing notes and standards to put on the drawing
On the purchase order, name the resin by trade name plus grade (Delrin 100/100P for POM-H, Hostaform C9021 or Sustarin C for POM-C are common electronics picks) and call out the flammability rating, food-contact status where relevant, colour, and lot traceability; the reference distributor offers batch control and traceability documentation as part of standard supply [S3].
For OEM electronics that ship globally, the BOM line should also reference the regulatory stack the part will be certified against: UL94 V-0 or V-2 for flammability, FDA or EU 10/2011 for food-grade POM, REACH and RoHS declarations for the European market, and where the part is used in a measuring or control instrument, IEC 61010-1 for the end product; the same instrument-level context is why sensor and instrument housings often pair a pressure sensor inside a PC/ABS enclosure with POM-C manifolds and click-fit couplers [S2][S3]. The two trackable signals to watch in the next sourcing cycle are: (1) whether EU food-contact and medical-grade POM-C supply normalises after the 2024-2025 chain disruptions, and (2) whether more electronics OEMs publish specific recycled-content POM grades with equivalent wear data, since current distributor literature still treats virgin POM as the default electronics spec [S3].
Spec-level background on the components involved: pressure transmitter.