Sealing Bulb: Cross-section diameter 3-15 mm

Component Specifications

Definition

The Sealing Bulb is a critical elastomeric component integrated into automotive weatherstrip assemblies, typically extruded or molded from specialized rubber compounds. It functions as the primary sealing element that compresses against vehicle body surfaces (doors, windows, trunks) to form continuous barriers against environmental elements. Its hollow or cellular structure allows controlled compression and recovery, maintaining consistent sealing pressure across temperature variations and vehicle movement while accommodating manufacturing tolerances.

Working Principle

Operates on compression sealing principles: when the weatherstrip is installed, the bulb deforms under compression against mating surfaces, creating a tight seal. Its elastic properties allow it to maintain constant contact pressure despite thermal expansion/contraction, vibration, and door/window movements. The hollow cross-section provides optimal balance between sealing force and closure effort.

Materials

EPDM (Ethylene Propylene Diene Monomer) rubber is standard (70-90% usage), with alternatives including TPV (Thermoplastic Vulcanizates), silicone for high-temperature applications, or foam-filled variants. Material specifications include: hardness 50-80 Shore A, tensile strength >10 MPa, compression set <25% (70h at 70°C), temperature range -40°C to +120°C, UV and ozone resistance per automotive standards.

Technical Parameters

Parameter	Typical range	Notes & selection driver
Color	Black (standard), custom available
Compression Set	<25%
Compression Force	0.5-3.0 N/cm
Weather Resistance	>1000h weatherometer
Operating Temperature	-40°C to +120°C
Cross Section Diameter	3-15 mm

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Standards

ISO 4633, ISO 3302, DIN 7716, SAE J200

Parent Products

This component is used in the following industrial products

Automotive Weatherstrip

An extruded rubber or thermoplastic elastomer profile designed to create a watertight, airtight, and dustproof seal between moving and fixed parts of an automobile.

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Engineering Analysis

Risks & Mitigation

Compression set leading to permanent deformation
UV degradation causing surface cracking
Chemical swelling from automotive fluids
Installation damage during assembly
Inconsistent cross-section affecting sealing pressure

FMEA Triads

Trigger: Material formulation error
Failure: Premature hardening or cracking
Mitigation: Strict raw material QC, accelerated aging tests per ISO 188

Trigger: Inconsistent extrusion dimensions
Failure: Variable sealing pressure along length
Mitigation: Laser measurement systems, SPC control of extrusion process

Trigger: Improper installation compression
Failure: Incomplete seal or excessive closure force
Mitigation: Precision jigs for assembly, compression force testing

Industrial Ecosystem

Compatible With

Typical Suppliers & Equivalents

Compliance & Inspection

Tolerance

±0.2mm cross-section dimensions, ±5% compression force variation

Test Method

Compression set per ISO 815, weather resistance per ISO 4892-2, adhesion tests per ISO 813, functional testing with simulated door closure cycles

Procurement Evaluation Criteria

A practical evidence checklist for RFQ preparation and supplier evaluation.

Technical documentation

Request current drawings, revision history, and a signed specification sheet.

Manufacturing capability

Verify equipment lists, process limits, capacity, and representative production evidence.

Inspection readiness

Confirm test methods, calibrated equipment, sampling plans, and traceable reports.

Supplier transparency

Check the legal entity, factory address, ownership, certifications, and direct contacts.

CNFX does not score or rank suppliers. Buyers must verify all claims and documents with the legal manufacturer before ordering.

Manufacturers of Sealing Bulb

Manufacturer profiles associated with Sealing Bulb.

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Frequently Asked Questions

What is the typical lifespan of an automotive sealing bulb?

Properly manufactured EPDM sealing bulbs typically last 10-15 years under normal conditions, maintaining sealing effectiveness through approximately 100,000 door cycles. Lifespan depends on material quality, UV exposure, chemical contact, and mechanical stress.

Can sealing bulbs be replaced individually?

Generally no - sealing bulbs are integrated into complete weatherstrip assemblies during manufacturing. Replacement requires installing the entire weatherstrip component. Some aftermarket repair strips exist for temporary fixes, but OEM replacement involves full assembly change.

How does temperature affect sealing bulb performance?

EPDM maintains elasticity from -40°C to +120°C. Below -30°C, hardness increases slightly but sealing maintains. Above 100°C, material softens but quickly recovers. Proper formulation ensures consistent compression set performance across the temperature range.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records. See the editorial policy.

Preliminary Technical Classification

This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

Sealing Bulb