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Cable Rubber Grommets

Category: Custom Rubber Parts

Cable rubber grommets seal and protect the point where a thick cable or a full wire-harness bundle passes through a metal or plastic panel. They're built for OEMs and panel builders who need the bore, groove, and flange matched to a specific cable envelope and panel thickness — not a bin of loose stock sizes. Send the cable OD, panel hole, and panel thickness, and the groove/flange geometry follows from there.

Cable & Panel Fit Specifications

Five core dimensions control whether a cable grommet seats correctly and stays retained under vibration or pull.

Dimension	What It Controls
Cable / Bundle OD	Bore size — fits the actual envelope without pinching the jacket
Panel Opening	Hole diameter or cutout the grommet must seat into
Panel Thickness	Groove width — too loose and the grommet walks out of the hole
Groove Depth	How firmly the grommet locks onto the panel edge
Flange OD	Coverage on each side of the panel

Dimensional precision on the bore and groove holds to the following tolerance bands:

Dimension Range	Standard Tolerance	Precision Tolerance
0–10mm	±0.10mm	±0.02mm
10–25mm	±0.15mm	±0.05mm
25–50mm	±0.20mm	±0.08mm
50–100mm	±0.25mm	±0.10mm

black neoprene cable component with three cylinders and side holes

Solid Bore vs. Split/Multi-Cable Grommets

Choose the grommet design according to the cable layout and panel opening:

Single round-bore grommets: For one larger cable passing through one panel hole. They offer a straightforward fit and simpler tooling.
Split-body or multi-bore grommets: For harness bundles with several conductors. The bundle can be installed through an opening body, or each conductor can pass through a separate molded bore.
Small-bore grommets: For single conductors or small cables. See rubber wire grommets.
Rectangular panel grommets: For square or rectangular cutouts. See standard rubber grommets.

Multi-bore designs require more tooling work because each bore must maintain its own sealing line without weakening the material between openings. They are worthwhile when routing individual wires through separate holes is impractical.

Sealing Grades & Material Options

Material selection drives heat, oil, and weather performance more than the grommet shape does.

Material	Typical Duty	Typical Continuous-Service Range
EPDM	Outdoor panels, ozone and weather exposure	−40°C to +120°C
NBR	Oily or greasy machinery environments	−30°C to +100°C
Silicone	Wide temperature swings, compliance-grade needs	−60°C to +200°C
Neoprene	General abrasion and mild chemical exposure	−40°C to +100°C

Hongjie’s compound library covers service temperatures from −60°C to +325°C for specialty applications. A close cable-to-bore fit can limit dust and light splash, but this does not represent a certified ingress rating.

For defined water-ingress protection, custom waterproof rubber grommets use a continuous sealing lip rather than relying only on cable-to-bore friction.

Automotive and appliance harness bundles can use custom wire-harness grommets sized to the OEM firewall or housing drawing. For wider temperature requirements or compliance-grade materials, custom silicone rubber grommets for cables use the same groove-and-flange design approach.

Manufacturing & Customization Capabilities

Cable grommets are produced by injection or compression molding from customer drawings, with in-house tooling for non-standard bores, grooves, and flange profiles. CAD files in STEP or IGES format support the drawing-to-quote process.

Industries & Applications

Automotive wiring harnesses
Route through firewall and body panels using Automotive Rubber options.
Electrical control panels
Take power and control cable entries into sheet-metal cabinets.
Appliance housings
Route power cords or internal cable groups through molded or metal enclosures.
Industrial equipment covers
Carry cable routing across machinery guards and outdoor housings.

Quality & Certifications

Standard	Scope
IATF 16949:2016	Process control for automotive harness and firewall grommet programs.
ISO 13485:2016	Quality documentation for medical device cable entries.
UL certification	Safety compliance for electrical panel and cabinet cable entries.
FDA/NSF-compliant materials	Compound options for appliance and food-adjacent equipment housings.

Dimensional and material consistency are held using SPC and Six Sigma methods, targeting Cpk > 1.33.

Request a Quote

Email your drawing and specs through our contact page for a drawing review. Include:

Cable or bundle OD (and number of conductors if it's a bundle)
Panel hole diameter and panel thickness
Groove width/depth and flange size needed
Material preference and any pull-through or strain-relief requirement
Target quantity

Functional prototypes follow within the timeframe below once tooling is approved:

Cable/Bundle OD	Panel Thickness (typical)	Flange OD	Prototype Lead Time
6–10mm	0.8–1.5mm	Sized to drawing	3–5 business days
10–20mm	1.0–2.5mm	Sized to drawing	3–5 business days
20–40mm	1.5–3.0mm	Sized to drawing	3–5 business days
40mm+ / multi-bore bundle	2.0–4.0mm	Sized to drawing	3–5 business days

Rubber grommets in assorted sizes and colors

For outdoor, wet or ozone-exposed panels, EPDM rubber grommets are the material-specific option.

Enclosure lids, doors and housings that must keep water out are covered under waterproof rubber seals.

FAQ

Frequently Asked Questions

What's the minimum order quantity (MOQ) for custom cable grommets?

There's no single company-wide MOQ — it tracks cavity count and bore geometry. Single-cavity, round-bore tools generally clear lower minimums than multi-bore harness designs with several sealing bores in one flange. The applicable minimum is confirmed during drawing review, not from a published price list.

How much does tooling cost, and how long does it take?

Tooling cost and lead time scale with cavity count, bore complexity, and steel finish rather than a flat rate, so neither is fixed across all cable grommet designs. A number follows drawing review; once tooling is approved, functional prototypes are ready in 3–5 business days.

How is pull-through force tested?

The assembled sample is pulled against the grommet at the force stated on the drawing, checking for cable movement or seal-line displacement at the groove. Pass/fail is set against that project-specific requirement rather than one generic number, since retention depends on cable jacket type and groove depth.

What tolerance can be held on the bore and groove?

Standard bore and groove tolerances run ±0.10mm to ±0.25mm depending on dimension size, tightening to ±0.02mm on critical features under 10mm. The applicable tolerance is set per drawing, not a blanket figure across all grommet sizes.

What are the rubber grommets called?

Cable grommets are also called cable bushings, panel bushings, or grommet seals depending on the industry. All describe the same molded rubber ring that lines a panel opening for cable or wire pass-through.

What is the rubber around a cable called?

That's the grommet or cable bushing sealing the panel opening — not the cable jacket itself, which is a separate extruded covering on the wire or cable.

What is a grommet for cable?

A cable grommet is a molded rubber ring sized to a cable's OD and a panel's hole and thickness, protecting the cable from sharp panel edges and helping retain it in the opening.

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