The quality inspection of the lumbar support airbag after welding is a key link to ensure the safety and functionality of the product. It requires a comprehensive assessment from multiple dimensions such as air tightness, mechanical properties, appearance, size and material characteristics. The following are the specific testing items and methods:
I. Air Tightness Testing
Purpose: Ensure no leakage after inflation and maintain normal operation.
Methods:
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Pressure Decay Method
- Inflate the airbag to rated pressure (e.g., 100-150 kPa), seal the valve, and monitor pressure changes.
- Failure criteria: Pressure drop exceeding specified limits (e.g., ≤5%/hour).
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Bubble Method
- Submerge the inflated airbag in water and observe for bubbles.
- Suitable for rapid detection of minor leaks.
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Helium Tracer Method
- Use helium as a tracer gas and detect leaks via mass spectrometry (high sensitivity).
Standards: Leak rate thresholds per product specifications or industry standards (e.g., ISO 16750).
II. Mechanical Performance Testing
Purpose: Verify strength and durability of welded joints to prevent failure during repeated inflation/deflation.
Methods:
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Burst Pressure Test
- Gradually increase internal pressure until rupture.
- Pass criteria: Burst pressure ≥2-3× design value (e.g., design: 200 kPa → burst ≥400 kPa).
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Fatigue Cycle Test
- Perform repeated inflation/deflation (e.g., 10,000 cycles) and check for cracks/deformation at welds.
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Peel Strength Test
- Measure peel force of welded joints using a tensile tester (requirement: ≥50 N/cm; reference: ASTM D1876).
III. Appearance & Dimensional Inspection
Purpose: Ensure defect-free products meet design specifications.
Methods:
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Visual Inspection
- Check welds for bubbles, scorch marks, misalignment, cracks, or contaminants.
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Dimensional Measurement
- Use calipers or optical measurement tools to verify length, width, thickness, and weld width (tolerance: e.g., ±0.5 mm).
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Weld Line Evaluation
- Ensure uniform weld lines; avoid localized thinning causing strength reduction.
IV. Material Property Testing
Purpose: Validate post-welding physical/chemical performance of materials.
Methods:
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Material Composition Analysis
- Analyze weld zones via FTIR or EDS to confirm no degradation/contamination.
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Weathering Test
- Expose airbags to high/low temperatures (-40°C to 80°C) or UV to assess performance changes.
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Chemical Resistance Test
- Test material swelling/discoloration under simulated sweat, grease, etc.
V. Functional Testing
Purpose: Ensure real-world performance of airbags.
Methods:
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Inflation Response Time Test
- Measure time from trigger to full inflation (requirement: ≤0.5 sec per safety standards).
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Pressure Distribution Test
- Use pressure sensors to ensure uniform surface pressure during inflation.
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Noise Test
- Measure noise levels during inflation (requirement: ≤65 dB to avoid user discomfort).
