POM-H · grade · default condition
POM-H Unfilled
Properties of the Unfilled condition, compared with the other POM-H grades.
Default choice for gears, bushings, clips and precision parts needing maximum stiffness and dimensional stability without fillers.
What is POM-H Unfilled?
POM-H Unfilled is POM-H in the Unfilled grade — default choice for gears, bushings, clips and precision parts needing maximum stiffness and dimensional stability without fillers. POM-H Unfilled has a yield strength of 70 MPa (10.2 ksi) and a tensile strength of 70 MPa (10.2 ksi) — stronger than 77% of polymer grades. Elongation at break is 30% and the elastic modulus is 3.1 GPa (0.45 Msi). POM-H Unfilled has a density of 1.42 g/cm³ (0.0513 lb/in³), heavier than 82% of polymer grades. Its glass-transition temperature is -60°C (-76 °F).
Advantages
- Easy to machine — 90/100, better than 95% of polymer grades
- Tough — resists crack growth — 4 MPa·√m (3.64 ksi·√in), better than 91% of polymer grades
- Conducts heat well — 0.31 W/m·K (0.179 BTU/hr·ft·°F), better than 86% of polymer grades
- Polishes to a fine finish — 70/100, better than 78% of polymer grades
- High strength — 70 MPa (10.2 ksi), better than 77% of polymer grades
Limitations
- High mold shrinkage — 2.1%, worse than 86% of polymer grades
- Heavy — 1.42 g/cm³ (0.0513 lb/in³), worse than 82% of polymer grades
- Degrades in UV without stabilisers — 25/100, worse than 76% of polymer grades
POM-H Unfilled properties
Typical room-temperature values for POM-H Unfilled — 11 properties are specific to this condition; the rest are grade-level values shared by every POM-H grade. Each bar shows where the value sits among the polymer grades in FabDigit's library — further right is higher.
Physical5
POM-H Unfilled has a density of 1.42 g/cm³ (0.0513 lb/in³), heavier than 82% of polymer grades. Its glass-transition temperature is -60°C (-76 °F).
Mechanical17
POM-H Unfilled has a yield strength of 70 MPa (10.2 ksi) and a tensile strength of 70 MPa (10.2 ksi) — stronger than 77% of polymer grades. Elongation at break is 30% and the elastic modulus is 3.1 GPa (0.45 Msi).
Thermal11
POM-H Unfilled is rated for continuous service to 95°C (203 °F). It conducts heat at 0.31 W/m·K (0.179 BTU/hr·ft·°F), better than 86% of polymer grades. Thermal expansion is 110 µm/m·K (61.1 µin/in·°F).
Electrical7
POM-H Unfilled is an electrical insulator with a dielectric strength of 20 kV/mm (508 V/mil) and a resistivity of 1×10¹³ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 72% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of POM-H Unfilled takes about 103 MJ of energy and emits 4.2 kg of CO₂ — less than 54% of polymer grades. Typical recycled content is 0%.
Manufacturability8
POM-H Unfilled's machinability is excellent (90/100, better than 95% of polymer grades); weldability fair (40/100); formability fair (45/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Other POM-H grades and fills
POM-H is also supplied in 14 other conditions. The full side-by-side table is on the POM-H overview.
- UnfilledDefaultDefault choice for gears, bushings, clips and precision parts needing maximum stiffness and dimensional stability without fillers.70 MPa tensile
- StandardDefaultThe everyday medium-viscosity molding grade (Delrin 500P class) balancing flow, toughness and cycle time.70 MPa tensile
- GF25Highest-stiffness standard acetal homopolymer grade for structural brackets and housings under sustained load.125 MPa tensile
- GF20Choose for higher stiffness, creep resistance and load-bearing temperature; accept brittleness, anisotropic shrinkage and abrasive wear on tools.105 MPa tensile
- EXTSemi-finished rod and plate for machined parts; annealed stock minimizes residual stress and post-machining distortion.68 MPa yield · 86 Shore D
- MoS2Economical low-wear bearing/gear grade where PTFE is not required; keeps most of the base stiffness.62 MPa tensile
- ESDFor electronics handling fixtures, fuel-system parts and conveyor components requiring charge dissipation.58 MPa tensile
- PTFE Filled (Delrin AF)Use for unlubricated bearings, slides and gears where the lowest coefficient of friction and stick-slip-free motion are required.50 MPa tensile
- IMChoose when notch sensitivity or cold impact governs — clips, latches and safety parts — at the cost of half the stiffness and strength.45 MPa yield · 75 Shore D
Working with POM-H Unfilled
Is POM-H easy to machine?
Outstanding to machine — sharp positive-rake tools, high speed, light feed, air or mist cooling; anneal 160 °C (slow cool) before finish cuts on tight-tolerance parts to relieve stress.
Can POM-H be welded?
No solvent cement bonds acetal; join by hot-plate, ultrasonic, spin or laser welding, or use mechanical fasteners; adhesive bonding needs plasma/flame or chromic-acid surface activation.
Can POM-H be formed, bent or molded?
Dry lightly (80 °C, 2–3 h) if wet, hold melt 205–225 °C and never exceed ~230 °C or dwell long (depolymerization/formaldehyde gas); mold at 80–120 °C, use generous gates and thick runners to feed the 2 % shrinkage and avoid voids in thick sections.
What surface finishes work on POM-H?
Machined or molded surfaces polish and burnish well; paints and adhesives require pre-treatment; can be laser-marked, hot-stamped or electroless-plated after specialized etch, but not anodized.
POM-H chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| heat/antioxidant stabilizer packagehindered phenol + formaldehyde scavenger (nitrogen compound), typical | 0.3 – 2 | 0.8 |
| acid scavenger / lubricantprocessing aid; grade dependent | 0.1 – 1 | 0.3 |
| carbon black / pigmentblack and UV grades only | 0 – 2 | 0.5 |
| glass fiberGF20/GF25 reinforcement variants | 0 – 25 | 0 |
| PTFEDelrin AF bearing variants | 0 – 20 | 0 |
| polyoxymethylene homopolymer (-CH2O-)acetate end-capped formaldehyde homopolymer | ≥ 97 (balance) | — |
POM-H Unfilled — frequently asked
What is POM-H Unfilled used for?
POM-H Unfilled is typically used for gears, sliding wear pads and bushings. In short: maximum hardness homopolymer.
What is the yield strength of POM-H Unfilled?
POM-H Unfilled has a typical yield strength of 70 MPa (10.2 ksi) and a tensile strength of 70 MPa (10.2 ksi) — stronger than 77% of polymer grades. Strength varies by condition: see the 15 listed tempers.
Is POM-H Unfilled easy to machine?
Yes — machinability is rated excellent (90/100, better than 95% of polymer grades). Outstanding to machine — sharp positive-rake tools, high speed, light feed, air or mist cooling; anneal 160 °C (slow cool) before finish cuts on tight-tolerance parts to relieve stress.
Can POM-H Unfilled be welded?
With care — weldability is rated fair (40/100). No solvent cement bonds acetal; join by hot-plate, ultrasonic, spin or laser welding, or use mechanical fasteners; adhesive bonding needs plasma/flame or chromic-acid surface activation.
What surface finishes work on POM-H Unfilled?
Machined or molded surfaces polish and burnish well; paints and adhesives require pre-treatment; can be laser-marked, hot-stamped or electroless-plated after specialized etch, but not anodized.
Can POM-H Unfilled be formed, bent or molded?
Dry lightly (80 °C, 2–3 h) if wet, hold melt 205–225 °C and never exceed ~230 °C or dwell long (depolymerization/formaldehyde gas); mold at 80–120 °C, use generous gates and thick runners to feed the 2 % shrinkage and avoid voids in thick sections.
What is the maximum service temperature of POM-H Unfilled?
POM-H Unfilled is rated for continuous use to about 95°C (203 °F), and briefly to 140°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between POM-H Unfilled and POM-H-IM?
Unfilled is the default condition — default choice for gears, bushings, clips and precision parts needing maximum stiffness and dimensional stability without fillers. IM: choose when notch sensitivity or cold impact governs — clips, latches and safety parts — at the cost of half the stiffness and strength. Yield strength is 70 MPa in Unfilled versus 45 MPa in IM.
Can FabDigit make parts in POM-H Unfilled?
Yes — POM-H Unfilled is available for CNC machining, sheet metal and injection molding with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- Delrin acetal homopolymer product and processing guides — DuPont / Celanese (Delrin brand) (2023)
- Tenac / Tenac-C polyacetal technical data — Asahi Kasei (2022)
- Ertacetal H / TECAFORM AH stock shape datasheets — Mitsubishi Chemical Advanced Materials / Ensinger (2023)
- CAMPUS plastics database — POM homopolymer ISO 10350 datasets — CAMPUS/CWFG (2024)
- ISO 9988 Plastics — Polyoxymethylene (POM) moulding and extrusion materials — ISO (2020)
- ASTM D6100 Standard Classification for Polyoxymethylene (POM) Molding and Extrusion Materials — ASTM (2020)
- Engineered Materials Handbook Vol. 2: Engineering Plastics — ASM International (1988)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.