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EPDM Rubber Grommets

Category: Custom Rubber Parts

EPDM rubber grommets protect wires, hoses, and tubing where they pass through a panel or enclosure wall, holding up outdoors, in vehicles, and in electrical housings where sun, ozone, and temperature swings degrade weaker elastomers. Hongjie molds them to standard and custom sizes as an OEM factory, from drawing to production.

Colorful rubber grommets sorted by hue and dimension against a clean backdrop

Why EPDM for Grommets

EPDM is suited to grommets used in outdoor or exposed environments rather than controlled indoor conditions. It resists ozone cracking, UV degradation and weathering better than NBR, while also handling water, steam and moderate chemical exposure.

That makes EPDM a practical choice for outdoor electrical equipment, appliances and enclosures, with a broad operating temperature range for both indoor panels and exposed installations. EPDM is not recommended for oil or fuel contact, where NBR or FKM grommets are usually a better choice.

Sizes, Shapes & Custom Options

SpecificationTypical range
Panel hole diameter~3mm to 50mm+ (larger on request)
Panel thickness~0.5mm to 6mm; groove width matched to the panel
Hardness40–70 Shore A (softer for easier fitting, harder for retention)
Service temperatureroughly −50°C to +150°C continuous
Mediawater, steam, coolant, ozone/UV, weathering — not petroleum oils or fuels
Tolerance±0.10mm standard on features under 10mm; ±0.02mm precision on request
black rubber U-pieces and grommets for custom molding

Beyond round-hole designs, EPDM grommets can be molded in panel-hole, D-shaped, multi-hole and blind configurations to match a specific cutout or harness bundle.

Hongjie draws on more than 3,500 existing tools across an 11,000 m² facility. Standard tolerances are ±0.10 mm on features under 10 mm, with precision tolerances down to ±0.02 mm. For features from 50–100 mm, standard tolerances are ±0.25 mm, with precision capability down to ±0.10 mm.

Custom rubber molding covers injection molding, compression molding, die-cutting and extrusion for parts beyond a single grommet profile. For square or rectangular panel cutouts, see rectangular rubber grommets.

Applications

Common EPDM Grommet Uses

EPDM grommets protect cable and wire pass-throughs in electrical panels and enclosures exposed to moisture, vibration and weathering.

Four black rubber grommets with metal inserts, arranged in a square.

Manufacturing & Quality

Production follows IATF 16949:2016 and ISO 13485:2016 quality systems, with FDA- and NSF-compliant material options and UL certification for electrical applications. These qualifications are relevant when EPDM grommets are specified for UL-reviewed enclosures.

Engineering support includes CAD review and material selection, while functional prototypes typically ship within 3–5 business days.

The broader EPDM rubber parts range includes washers, seals and diaphragms molded from the same compound. For compound-specific data, see EPDM material properties, including hardness, compression set and chemical resistance.

Request a Quote

Request a Quote

Upload a drawing for an OEM quote and get functional prototypes in as little as 3–5 business days, with export packaging for shipments across Hongjie's 45+ export markets. Browse the full custom rubber parts range or contact Hongjie's engineers directly with sizes and quantities.

FAQ

Frequently Asked Questions

What does EPDM rubber stand for?
Ethylene Propylene Diene Monomer — a synthetic rubber known for weather, ozone, and UV resistance, commonly used for outdoor and electrical grommets.
Is EPDM better than silicone?
EPDM typically costs less and offers excellent weather/ozone resistance for general outdoor and electrical use; silicone suits higher-temperature or food/medical-grade applications. The right choice depends on the operating environment.
Can EPDM grommets be certified for use in UL-reviewed electrical enclosures?
Hongjie holds UL certification for electrical applications, and EPDM's ozone and weather resistance make it a common material choice for grommets used in enclosures subject to UL review.
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