I. Core Pain Points of Silicone Extruded Gaskets

These issues arise from both end-users and application requirements, and must be addressed directly through production quality control.

II. How to Systematically Control Production Quality

A full-process quality control system must be established, from raw material (source) to finished product (output).

1. Source Control: Raw Materials & Formulation

• Strict Supplier Qualification: Choose reputable suppliers for silicone base polymers, fumed silica, and additives to ensure batch-to-batch consistency.

• Formula Management: Scientific Design: Formulations tailored to end-use (temperature, media, strength) and validated through testing.

• Fixed Recipes: Once validated, mass production must use fixed formulas. Any change requires strict re-validation.

Incoming Quality Control (IQC): Inspect every raw material batch (e.g., molecular weight of silicone base, surface area of silica, purity of curing agents).

2. Process Control: Manufacturing & Equipment

This is the core link of quality assurance.

• Mixing Process: Ensure uniform dispersion, no unmixed “dead material” or agglomerates.

• Control temperature and time to avoid premature curing (scorching).

Extrusion Process: Die Design: Critical for dimensional accuracy. Must account for compound swelling (die swell).

Process Parameters: Precisely control extruder temperature, screw speed, and feed rate to ensure smooth surface and stable dimensions.

Curing Process: The key step that defines mechanical properties.

Strictly control cure temperature, time, and speed (e.g., microwave curing, hot air oven profiles).

Under-cure → tacky, weak product; over-cure → brittle, reduced aging resistance.

Post-processing: Secondary vulcanization (post-cure): Very important! Removes volatile residues, reduces compression set, improves thermal stability, and lowers odor.

Surface treatments: e.g., flocking—must ensure adhesive bond strength, evenness, and abrasion resistance.

3. Inspection Control: Full-process Quality Checks

Implement a system of self-inspection, mutual inspection, and dedicated QC inspection.

• First-article Inspection: After each startup or die change, the first product must pass dimensional and visual checks before batch production.

• In-process Inspection (IPQC): Regular sampling during production to monitor process stability and key product characteristics (size, weight).

• Final Inspection (FQC/OQC): 100% or sampling inspection before shipment, including: Dimensional Checks: Projector, calipers, laser gauges.

• Appearance Checks: Visual or light-box inspection.

• Performance Tests: Mechanical properties: tensile strength, elongation, hardness (Shore A).

• Key indicator: Compression set (mandatory!).

• Aging resistance: yellowing, ozone, flame-retardant grade.

• Functional: leak-proof, waterproof, as per customer requirements.

4. System & Management Control

• Quality Management System: Establish and certify under ISO 9001, and enforce document-based, standardized management.

• Equipment Maintenance & Calibration: Regularly maintain and calibrate production (extruders, ovens) and inspection equipment (measuring tools, tensile testers).

• Staff Training: Continuous operator and QC staff training to improve skills and awareness.

• Traceability: Ensure full traceability from raw material lot → production shift → finished batch, enabling fast root cause identification when issues occur.

III. Recommendations for Buyers & QC Personnel

1. Select the Right Supplier: Choose manufacturers with strong technical expertise, complete QC systems, and in-house testing—not just the cheapest.

2. Define Standards Clearly: Include all technical and acceptance standards (e.g., tolerances, physical property specs, AQL level) in contracts.

3. Focus on Compression Set: Make this a key acceptance criterion, and require suppliers to provide test reports.

4. Request Inspection Reports: Each shipment should include factory QC reports, and periodically request third-party (e.g., SGS) test reports.

5. On-site Audits: If possible, audit supplier factories to verify process control, inspection capability, and production environment.

Conclusion

Only by implementing such a systematic quality management approach can manufacturers effectively resolve the common pain points of silicone sealing strips and consistently deliver high-quality, reliable products.