ACM vs EPDM
Polymer · grade comparison
ACM and EPDM are both polymer grades. EPDM is the stronger of the two: tensile strength 12 MPa (1.74 ksi) against 11 MPa (1.6 ksi) for ACM, about 9% more. EPDM is the more ductile: elongation 400% versus 220% for ACM. EPDM is lighter (1.15 g/cm³ vs 1.25 g/cm³ for ACM) and ACM runs hotter in service (150°C vs 120°C continuous). On the shop floor, EPDM sits in a lower cost tier (standard, $$) than ACM (premium, $$$).
ACMChoose it when the part sees heat.
EPDMChoose it when strength drives the design, or when the part is bent, formed or impact-loaded.
ACM vs EPDM: propertiesHow to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
How to read these bars
- One bar per material. A full bar is the highest value among all polymer grades in the FabDigit library; each bar is drawn as a share of that.
- The better value (by the usual engineering direction) is in bold. Rows with no direction — density, thermal conductivity — have no bold.
- Values are typical room-temperature figures for the condition named on each card.
- Confirm against the certified mill or resin datasheet before design release.
Mechanical
Strength, stiffness, ductility and hardness at room temperature.
Tensile Strength (Ultimate)
Elongation at Break
Tear Strength
Same in both: Elastic (Young's) Modulus 0.01 GPa8.7×10⁻⁴ Msi · Shear Modulus 0 GPa2.9×10⁻⁴ Msi · Bulk Modulus 2 GPa0.29 Msi · Poisson's Ratio 0.5 · Hardness, Shore A 70 Shore A · Hardness, Shore D 22 Shore D · Compression Set (22 h, 70 °C) 20%
Physical
Density and transition temperatures.
Density
Glass Transition (Tg)
Water Absorption (24 h)
Thermal
How each material carries heat and how hot it can run.
Thermal Conductivity
Specific Heat Capacity
Thermal Expansion (CTE, 20–100 °C)
Max Service Temperature (continuous)
Min Service Temperature
Limiting Oxygen Index
Max Service Temperature (short-term)
Electrical
Conductivity and insulation.
Electrical Resistivity
Dielectric Strength
Dielectric Constant (1 MHz)
Dissipation Factor (1 MHz)
Volume Resistivity
Comparative Tracking Index (CTI)
Chemical & Environmental
Corrosion and environmental resistance (0–100 scores).
Corrosion Resistance
UV / Weathering Resistance
Manufacturability
FabDigit workshop ratings (0–100 scores) — how each material behaves on the machine.
Formability (cold)
Mold Shrinkage
Mold Temperature (typ.)
Weldability
Polishability
Processing Melt Temperature (typ.)
Same in both: Machinability 30 / 100
Sustainability
Primary-production footprint per kilogram.
Embodied Energy (primary production)
Embodied Carbon (primary production)
Embodied Water
Typical Recycled Content
Common Calculations
Ratios derived from the values above.
Specific Strength (UTS / density)
Thermal Shock Resistance Index
Same in both: Specific Stiffness (E / density) 0 MN·m/kg · Thermal Diffusivity 0.1 mm²/s
Strength versus weight
Yield strength against density for every polymer grade in the FabDigit library; the compared grades are highlighted. Up and left is stronger for its weight.
Manufacturing and finishing
| Capability | ACM | EPDM |
|---|---|---|
| Injection molding | — | Yes |
| Default condition | — | Solid |
| Relative cost | $$$ Premium | $$ Standard |
| Min. machined wall | — | — |
| Best machined surface | — | — |
| Chrome Plating (Plastic) | — | Yes |
| EMI Shielding Coating | — | Yes |
| Soft Touch Coating | — | Yes |
| Spray Painting | — | Yes |
| UV Coating | — | Yes |
ACM vs EPDM — frequently asked
Is EPDM stronger than ACM?
Yes. EPDM has a typical tensile strength of 12 MPa (1.74 ksi) against 11 MPa (1.6 ksi) for ACM — about 9% more.
Which is cheaper, ACM or EPDM?
EPDM is the lower-cost material: it sits in the standard tier ($$) while ACM is premium ($$$). Part price depends far more on geometry, tolerance and quantity than on raw stock — upload a CAD file for a live quote.
When should I choose ACM over EPDM?
Pick ACM when the part sees heat. Pick EPDM when strength drives the design, or when the part is bent, formed or impact-loaded.
Ready to make it?
Upload a CAD file and FabDigit prices the part in ACM and EPDM side by side — material, machining time, tolerance and finish in one quote. Certified material data ships with the order on request.
Typical handbook values for the conditions named above, normalised for comparison. Hardness on non-Brinell scales is converted approximately for charting only. Request certified data with your order for design-critical properties.