EPDM is the elastomer you specify for weather. It resists ozone, UV, rain and temperature cycling better than any other general-purpose rubber, which is why it owns automotive weatherstripping, roofing membranes and outdoor seals. It also handles hot water and steam well. What it does not tolerate is oil — EPDM swells badly in hydrocarbon fluids, so the first question on any EPDM enquiry is what the part touches.

Custom EPDM Rubber Moulding — Automotive door, window and boot seals

40 – 90 Shore AHardness range
-50 to +150 °CService temperature
7 – 15 MPaTensile strength

Typical values for standard moulding grades. Exact figures depend on the specific compound or grade — confirm against your drawing before quoting.

Key properties

プロパティ Typical value
Hardness range 40 – 90 Shore A
Service temperature -50 to +150 °C
Tensile strength 7 – 15 MPa
Elongation at break 200 – 500 %
Compression set (22 h / 70 °C) 15 – 25 %
Weather and ozone Excellent — best of the general-purpose rubbers

Values are typical for unfilled moulding grades at 23 °C unless stated. Glass-filled and specialty grades differ.

Typical applications

  • Automotive door, window and boot seals
  • Roofing membranes and construction gaskets
  • Radiator and heater hoses
  • Outdoor cable jackets and connectors
  • Steam and hot-water seals

Processing notes

  • EPDM is not oil resistant. Even light contact with grease or fuel causes significant swell — confirm the media before specifying.
  • For weatherstrip, the compound matters as much as the polymer. Specify the ozone and UV test rather than just 'EPDM'.
  • Peroxide-cured EPDM gives better compression set and heat resistance than sulphur-cured; it costs more and is harder to mould.
  • Bonding to metal or plastic needs an EPDM-specific primer and a clean substrate. Mechanical interlock is more reliable in high-vibration assemblies.
Tooling, not just material. Every material above behaves differently in the tool — shrinkage, gate position, cooling and ejection all change. We review the DFM against the specific grade before the tool is cut, so the first shot is a sample, not a surprise.

Frequently asked questions

Can EPDM be used outdoors for 20 years?

In a properly formulated compound, yes — EPDM weatherstripping routinely lasts that long. The stabiliser package and carbon black loading do the work; a cheap compound will crack within a few years.

Why did my EPDM part swell up?

Almost certainly contact with oil, grease or fuel. EPDM has essentially no hydrocarbon resistance. Switch to NBR for oil or FKM for hot oil.

Related materials

← All Rubber & Silicone Solutions

Send us your EPDM Rubber drawing

Upload a 3D model or a 2D drawing and we will come back with a DFM review, a tooling cost and a piece price — usually within two working days.

Request a quote

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