IP68 Silicone Cable Grommets for Electric Vehicle Wire Harnesses

Industry & Application Overview

Electric vehicle platforms route high-voltage and low-voltage harnesses through body panels, battery pack enclosures, inverters and motor housings. Every penetration point is a potential path for water, dust and vibration to reach sensitive electronics. Cable grommets are the elastomeric seals that close these pass-throughs and maintain the ingress protection rating of the enclosure, which for EV systems is often IP67 or IP68. Because harness routing changes frequently during vehicle development, grommets must be custom-fit, durable and available without long lead times.

Dongguan Yunze Silicone Products Co., Ltd. produces custom silicone cable grommets for EV harness makers, battery pack integrators and Tier 1 electrical suppliers.

Engineering Challenge & Pain Points

A harness integrator building battery pack wiring for an EV programme replaced EPDM grommets with silicone after recurring field failures. Their pass-throughs carried cables from 6 mm to 32 mm in diameter through a 1.5 mm stamped steel wall. Problems included:

• Water ingress: EPDM grommets took a compression set at 105 °C and lost their sealing force, so IP68 test panels failed after thermal cycling.
• Vibration fatigue: road and motor vibration chafed the grommet lip and the cable jacket, risking insulation damage and short circuits.
• Wide diameter scatter: a single grommet could not accommodate the tolerance spread of both cable and hole, causing leaks on the loose end and difficult installation on the tight end.
• Assembly errors: reversed or under-seated grommets were hard to detect on a fast-moving line.

Yunze Silicone Custom Solution & Material Selection

Yunze selected a high-tear-strength platinum-cured silicone (VMQ) with a wide temperature range of -60 to 200 degrees Celsius and excellent resistance to compression set. Silicone was preferred over EPDM because it retains elasticity over a far wider thermal window and does not harden in cold or under sustained heat.

• Multi-rib sealing geometry that grips the cable and the panel wall simultaneously.
• Compression set under 20 % at 175 °C for 22 hours, ensuring long-term seal force.
• Cut-resistant inner bore and rounded lip to protect cable jackets from chafing.
• Asymmetric flange and orientation key to prevent reverse installation.
• Supplied with pre-cut split versions for retrofitting around terminated harnesses.

Technical Specifications

Quantified Performance Results & Benefits

• IP68 panels passed 1,000 thermal cycles from -40 to 125 °C without leakage.
• Assembly defect rate fell from 3.1 % to 0.5 % after the orientation key was introduced.
• Grommet pull-out force increased by 60 % versus the previous EPDM part.
• Cable jacket chafing failures reduced to zero over a 12-month field sample.
• Tooling and first articles delivered in 10 days, supporting the customer's fast harness revisions.

Technical FAQ

Q: Can your grommets really achieve IP68?
A: Yes. When the grommet is matched to the correct cable and hole diameter, our multi-rib design holds IP68. We validate with water immersion and thermal-cycling tests and can provide test reports.

Q: Do you offer split grommets for already-terminated harnesses?
A: Yes. Pre-cut split grommets allow installation around connectors without de-pinning the harness, and a matching adhesive or clip option keeps them closed.

Q: Which hardness should we choose?
A: 50 Shore A is standard for robust seals. Choose 40 Shore A when installation force must stay low on fragile panels, or a firmer compound for high-pressure washdown areas.

Engineering Consultation & Sample Request

Send your cable diameters, panel thickness and required IP rating to Dongguan Yunze Silicone Products Co., Ltd. Our engineers will recommend the rib profile, hardness and material grade, then ship free samples for your own IP and thermal-cycling validation.