POM Injection Molding
We mold POM (Acetal) (and compatible grades) for functional, structural and aesthetic parts — from low-volume bridge production to high-volume runs.
POM: The Plastic That Replaces Metal
POM (acetal / Delrin) is the closest plastic to metal for gears and moving parts — data per FirstMold's POM page (https://firstmold.com/pom-injection-molding/).
High rigidity and strength — metal-like stiffness in thin sections, ideal for gears, cams and levers.
Self-lubricating with low friction — runs dry against steel and other plastics with minimal wear.
Excellent fatigue resistance — survives repeated bending and impact in clips, springs and latches.
Good wear resistance and dimensional stability — FirstMold holds defect rates under 1 % in mass production.
Thermal stability — keeps properties across automotive temperature ranges.
Modified variants extend it further — toughened, wear-resistant (PTFE/oil-filled) and UV-protected grades.
Excellent spring-back — POM acts like a spring in clips and snap-fits, returning to shape after repeated deflection.
Dimensional stability — low moisture uptake keeps tolerances stable in humid environments.
Creep resistance — keeps clamp forces and preload in fasteners and press-fits over time.
Low noise — POM gears run quieter than metal in motors and actuators.
Metal-replacement economics — POM costs far less than machined brass or steel for high-volume gears.
POM Processing Parameters We Control
Shrinkage window (1.5–2.5 %) and process ranges per published POM datasheets; MOLDITQUICK runs POM on Sodick presses with in-house tooling.
| Parameter | Recommended Range | Why It Matters |
|---|---|---|
| Barrel temperature | 190–220 °C | Full plasticization without thermal degradation of the acetal chain. |
| Mold temperature | 80–100 °C | Hot molds improve surface and dimensional consistency of crystalline POM. |
| Mold shrinkage | 1.5–2.5 % | Higher than most engineering plastics — cavity sizing and gate design compensate. |
| Drying | 80–90 °C, 2–4 h | Not hygroscopic, but surface moisture must be removed for clean surfaces. |
| Gate & runner | Short, generous gates preferred | POM solidifies fast — generous gates keep hold pressure effective. |
| Venting | Short, wide vents | Processing gases must escape the cavity to prevent burning. |
| Ejection & draft | 0.5–1° draft minimum | Rigid POM needs draft to release cleanly without scuffing. |
POM Grades We Mold
Homopolymer vs copolymer and modified grades per FirstMold's POM material expertise (https://firstmold.com/pom-injection-molding/).
Where POM Injection Molding Pays
Automotive & EV
Door lock mechanisms, window lift gears and sliders, seat belt components, power steering parts and suspension bushings.
Machinery
Gears and sprockets, conveyor components, valve bodies, rollers, precision screws and nuts, sliding and guiding elements.
Electrical & electronics
Switch components, coil bobbins, light sockets, relay cases, cable clips and wire-harness parts.
Precision instruments
Optical lens mounts, analytical instrument components, surgical instruments, sealing rings and camera gears.
Consumer goods
Pen barrels and caps, zippers, toys, mascara wands and fire hydrant components in corrosion-resistant POM.
Fluid handling
Pump impellers, valve seats and fittings that hold tolerance in water and fuel contact.
Fasteners
Precision screws, nuts and inserts molded in one piece with bosses.
Office & furniture
Chair mechanisms, drawer slides and height-adjuster gears that flex and slide for years.
POM Design Rules We Enforce
- ✓POM shrinks 1.5–2.5 % — size the cavity and account for the crystalline nature of the resin.
- ✓Design gear teeth with POM's fatigue behavior in mind; keep tooth roots generous to avoid stress raisers.
- ✓Avoid thick sections where centerline porosity can form — use copolymer POM or redesign the wall.
- ✓Place gates so weld lines stay away from loaded areas — a weld line in a gear tooth is a failure point.
- ✓Use short, generous gates and runners — POM sets up fast and needs effective hold pressure.
- ✓For moving parts, specify wear-resistant grades when running against steel or other plastics.
- ✓Vent molds well — POM can release formaldehyde at high melt temperatures; proper venting protects both part and tool.
- ✓Plan press-fit allowances — POM's low friction and creep behavior change interference-fit design.
- ✓Design living snap-fits with generous flex roots — POM tolerates millions of cycles when the root radius is right.
POM Injection Molding FAQ
- ✓Q: Can POM replace metal parts? A: Yes — gears, bushings and levers in POM run quieter, lighter and without lubrication, with metal-like stiffness.
- ✓Q: Does POM need lubrication? A: No — it is self-lubricating; PTFE/oil-filled grades lower friction further for high-wear applications.
- ✓Q: What tolerances can POM hold? A: Tight molded tolerances are achievable, but its 1.5–2.5 % shrinkage must be designed in — DFM review happens before tooling.
- ✓Q: Homopolymer or copolymer POM? A: Homopolymer for strength and stiffness; copolymer for chemical and thermal stability and thick-wall soundness.
- ✓Q: What lead time for POM parts? A: Low volume 7–12 days, production 25–30 days, with in-house tooling and DFM.
- ✓Q: Can POM parts run against metal? A: Yes — POM is self-lubricating against steel and aluminum; wear-resistant grades extend life further.
- ✓Q: Does POM absorb moisture? A: Very little — drying is quick (80–90 °C, 2–4 h) and dimensions stay stable in humid environments.
- ✓Q: What finish can POM parts have? A: Silk screening, etching, laser engraving and spraying are proven; electroplating runs with our long-term partner.
- ✓Q: Can POM be used for food contact? A: Some POM grades meet food-contact norms — we verify the specific grade against your compliance list at DFM.
- ✓Q: What quality systems cover POM production? A: IATF16949, ISO13485 and ISO9001 — the same systems we run for every material program.
Related Capabilities
Explore the full range of MOLDITQUICK manufacturing services.