POM-H HI
also Delrin 100ST, Tenac-C 4520
POM-H HI is an elastomer-toughened acetal homopolymer, equivalent to Delrin 100ST and Tenac-C 4520.
Reference datasheet — POM-H HI is not in the instant-quote catalog. Upload your part and an engineer will quote it in this grade or suggest the closest stocked equivalent.
Values for the ST condition
POM-H HI grades and fills
POM-H HI is supplied in 6 conditions, soft to hard. ST is the default FabDigit quotes; the values on this page are for it.
Compare all 6 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Internally lubricated toughened grade | For toughened parts that also slide: lower friction and wear against steel, at the cost of some strength and weld-line integrity. | 40 | 40 | 120 | 71 Shore D |
STDefault Solution annealed | Pick when maximum notched impact and ductile failure down to -40 °C matter more than stiffness (Delrin 100ST class). | 45 | 45 | 220 | 72 Shore D |
Carbon-black pigmented toughened grade | Standard black colour version; carbon black gives moderate light screening at no property penalty. | 45 | 45 | 200 | 72 Shore D |
Heat-stabilized / low-emission toughened grade | For long-term hot-air or hot-oil service (automotive interiors, fuel systems) where formaldehyde emission and thermal ageing must be controlled. | 46 | 46 | 190 | 73 Shore D |
Moderately toughened homopolymer | Best compromise grade: roughly 5x the notched impact of standard POM-H while keeping useful stiffness and HDT (Delrin 100T/500T class). | 52 | 52 | 130 | 76 Shore D |
High-flow toughened injection grade | Choose for thin-wall, multi-cavity or long-flow-path parts where fill pressure limits the low-MFR super-tough grades. | 53 | 53 | 90 | 78 Shore D |
Supply forms, finishes and certifications
Ways POM-H HI is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FDA | Food-contact / medical compliant toughened natural | Certification |
UV | UV/weather-stabilized | Grade option |
What is POM-H HI?
POM-H HI is an elastomer-toughened acetal homopolymer, equivalent to Delrin 100ST and Tenac-C 4520. The dispersed rubber phase raises notched impact strength and low-temperature toughness well above standard POM-H, giving 220 % elongation at 45 MPa tensile strength and 1.34 g/cm3 density, which suits snap-fits and repeatedly flexed hardware. Maximum service temperature is 85 °C and stiffness and machinability (rated 72) are lower than unmodified acetal, so it is not the choice for rigid gearing. Toughened, high-flow, UV, black, heat-stabilised, FDA and lubricated conditions are on file; standard POM-H or POM-C GF25 is the alternative when stiffness dominates. POM-H HI has a density of 1.34 g/cm³ (0.0484 lb/in³), heavier than 74% of polymer grades. Its glass-transition temperature is -60°C (-76 °F). POM-H HI has a yield strength of 45 MPa (6.53 ksi) and a tensile strength of 45 MPa (6.53 ksi) — weaker than 58% of polymer grades. Elongation at break is 220% and the elastic modulus is 1.4 GPa (0.203 Msi).
What is POM-H HI used for?
- seat belt components
- snap-fit fasteners
- sporting goods hardware
- handle and lever mechanisms
Advantages
- Tough — resists crack growth — 6.5 MPa·√m (5.92 ksi·√in), better than 100% of polymer grades
- Ductile — tolerates forming and impact — 220%, better than 77% of polymer grades
- Easy to machine — 72/100, better than 76% of polymer grades
Limitations
- Needs corrosion protection — 68/100, worse than 85% of polymer grades
- High mold shrinkage — 2%, worse than 81% of polymer grades
POM-H HI properties
Typical room-temperature values for POM-H HI-ST; bars are the position among polymer grades.
Physical5
POM-H HI has a density of 1.34 g/cm³ (0.0484 lb/in³), heavier than 74% of polymer grades. Its glass-transition temperature is -60°C (-76 °F).
Mechanical16
POM-H HI has a yield strength of 45 MPa (6.53 ksi) and a tensile strength of 45 MPa (6.53 ksi) — weaker than 58% of polymer grades. Elongation at break is 220% and the elastic modulus is 1.4 GPa (0.203 Msi).
Thermal11
POM-H HI is rated for continuous service to 85°C (185 °F). It conducts heat at 0.25 W/m·K (0.144 BTU/hr·ft·°F), better than 72% of polymer grades. Thermal expansion is 125 µm/m·K (69.4 µin/in·°F).
Electrical7
POM-H HI is an electrical insulator with a dielectric strength of 18 kV/mm (457.2 V/mil) and a resistivity of 1×10¹² Ω·m.
Chemical & Environmental3
Corrosion resistance is good (68/100), worse than 85% of polymer grades. UV resistance is poor.
Sustainability4
Producing a kilogram of POM-H HI takes about 92 MJ of energy and emits 4.4 kg of CO₂ — less than 74% of polymer grades. Typical recycled content is 0%.
Manufacturability8
POM-H HI's machinability is very good (72/100, better than 76% of polymer grades); weldability fair (45/100); formability good (60/100).
Common Calculations5
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polymer family
Yield strength against density for every polymer grade FabDigit runs. POM-H HI is highlighted; hover a dot for its name, or open the interactive family chart.
Working with POM-H HI
Is POM-H HI easy to machine?
Machines cleanly with sharp positive-rake tools and high speed, but the rubber phase makes it gummier than standard POM-H — use light finishing cuts, air blast, and expect stress-relief distortion on thick sections (anneal 150 °C in air).
Can POM-H HI be welded?
Hot-plate, vibration, spin and ultrasonic welding work with moderate joint strength; solvent bonding is impossible and adhesives need flame/plasma or chromic-acid etch pretreatment.
Can POM-H HI be formed, bent or molded?
Dry to <0.1 % moisture if pellets are wet, melt 205–225 °C, mould 80–110 °C, use generous gates and 1.7–2.4 % shrink allowance; avoid melt residence >20 min and never mix with PVC or acidic resins to prevent formaldehyde decomposition.
POM-H HI 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 |
|---|---|---|
| elastomer impact modifier (thermoplasticdispersed rubber phase, grade dependent | 10 – 25 | 18 |
| antioxidant / formaldehyde scavenger / athermal stabilizer package | 0.3 – 1.5 | 0.8 |
| lubricant, nucleant, pigmentprocessing aids and colour | 0 – 2.5 | 0.7 |
| polyoxymethylene homopolymer (formaldehyend-capped POM-H resin | ≥ 75 (balance) |
What surface finishes work on POM-H HI?
Takes machining/tumble finishing and laser marking well; painting, plating or printing require surface activation because of the low-energy, chemically inert surface.
Equivalent designations
Standards and trade names that resolve to POM-H HI in FabDigit's catalog. Equivalence is nominal — check the exact specification when certification matters.
- Trade names
- Delrin 100STTenac-C 4520
How much does POM-H HI cost?
POM-H HI is a premium-cost polymer ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
POM-H HI — frequently asked
What is POM-H HI used for?
POM-H HI is typically used for seat belt components, snap-fit fasteners, sporting goods hardware and handle and lever mechanisms. In short: toughest acetal grade; ductile at low temperature; snap-fit and clip resin.
What is the yield strength of POM-H HI?
POM-H HI has a typical yield strength of 45 MPa (6.53 ksi) and a tensile strength of 45 MPa (6.53 ksi) — weaker than 58% of polymer grades. Strength varies by condition: see the 6 listed tempers.
Is POM-H HI easy to machine?
Yes — machinability is rated very good (72/100, better than 76% of polymer grades). Machines cleanly with sharp positive-rake tools and high speed, but the rubber phase makes it gummier than standard POM-H — use light finishing cuts, air blast, and expect stress-relief distortion on thick sections (anneal 150 °C in air).
Can POM-H HI be welded?
With care — weldability is rated fair (45/100). Hot-plate, vibration, spin and ultrasonic welding work with moderate joint strength; solvent bonding is impossible and adhesives need flame/plasma or chromic-acid etch pretreatment.
What surface finishes work on POM-H HI?
Takes machining/tumble finishing and laser marking well; painting, plating or printing require surface activation because of the low-energy, chemically inert surface.
Can POM-H HI be formed, bent or molded?
Dry to <0.1 % moisture if pellets are wet, melt 205–225 °C, mould 80–110 °C, use generous gates and 1.7–2.4 % shrink allowance; avoid melt residence >20 min and never mix with PVC or acidic resins to prevent formaldehyde decomposition.
What is the maximum service temperature of POM-H HI?
POM-H HI is rated for continuous use to about 85°C (185 °F), and briefly to 130°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
What is the difference between POM-H HI ST and POM-H HI HF?
ST is the default condition — pick when maximum notched impact and ductile failure down to -40 °C matter more than stiffness (Delrin 100ST class). HF: choose for thin-wall, multi-cavity or long-flow-path parts where fill pressure limits the low-MFR super-tough grades. Yield strength is 45 MPa in ST versus 53 MPa in HF.
How much does POM-H HI cost?
POM-H HI is a premium-cost polymer ($$$), cheaper than about 51% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Sources
- Delrin 100ST / 500T acetal homopolymer product data — DuPont / Delrin (Celanese) (2023)
- Tenac / Tenac-C acetal resin grade list — Asahi Kasei (2022)
- CAMPUS plastics database — impact-modified POM homopolymer datasets (ISO 10350-1) — CAMPUS / CWFG (2024)
- Engineered Materials Handbook Vol.2: Engineering Plastics — ASM International (1988)
- ISO 9988-1/-2 Plastics — Polyoxymethylene (POM) moulding and extrusion materials — ISO (2020)
- GB/T 24283 (POM) — SAC (2009)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.