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Airbag Inflator Laser Weld Failure: Analysis and Minimization

Airbag Inflator Laser Weld Failure: Analysis and Minimization. Team Cleanweld , University of Idaho: Ken Bean, David Hewitt, Tess Howell, Nathan Jerred , Erik Shallman Advisor: Dr. David Drown May 1, 2009. Overview. Client Project Introduction Prior Analysis and Scope Objectives

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Airbag Inflator Laser Weld Failure: Analysis and Minimization

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  1. Airbag Inflator Laser Weld Failure:Analysis and Minimization Team Cleanweld, University of Idaho: Ken Bean, David Hewitt, Tess Howell, Nathan Jerred, Erik Shallman Advisor: Dr. David Drown May 1, 2009

  2. Overview • Client • Project Introduction • Prior Analysis and Scope • Objectives • Stored Gas Inflator • Wash Process • Spectrometry and Microscopy • Methods and Results • Recommendations

  3. Client • Autoliv Inc. • A worldwide leader in automotive safety • Products include seatbelts, airbags, child restraints, etc. • Products used by all major auto manufacturers • Based in Brigham City, Utah

  4. Project Introduction • Stored Gas Airbag Inflator • Three-Step Cleaning Cycle • “Leakers” • Represent loss of product • Autoliv’s Prior Analysis • Inflators are leaking due to failing laser welds • Failures not caused by welding parameters • Failure possibly due to surface contamination from the wash process • Scope of Research • Focus on burst disk laser welds • Includes a study of weld surfaces and wash process

  5. Objectives • Determine the effects of wash and rinse compositions on laser-weld failure • Identify surface contaminants present on inflators • Explore existing failures to determine leak rates • Examine the laser weld using optical microscopy • Analyze the composition of the wash detergent and rinse solutions • Recommend strategies to reduce weld failures and operational costs

  6. Stored Gas Inflator Inconel™ Disk The Diffuser The Initiator The Body

  7. Stored Gas Inflator

  8. Current Wash System • JenFab Drum Washer Part Flow Wash Rinse 1 Rinse 2 Dry Send Return Send Return Rinse + RP Wash Tap Water + RP Wash Solution

  9. Helium mass spectrometry • HMS confirmed inflators were leaking • Sniffer wand confirmed leaks from initiator burst disks only

  10. Scanning electron microscopy • Two inflators tested: • “As received” – taken directly off Autoliv’s wash process assembly line • “Clean” – washed in the lab with acetone and ethanol • Identified surface residue with EDS analysis • Compared the cleanliness of the inflators

  11. Scanning electron microscopy “As Received” “Clean”

  12. Optical Microscopy • Laser weld with Porosity • Laser weld without porosity

  13. Methods & Results • Inductively Coupled Plasma (ICP) • Provides the elemental composition of the solutions • pH • Enable us to compare the basicity of the solutions with their respective leaker data and draw important conclusion • Potassium Ion Selective Electrode (ISE) • Converts the activity of a specific ion dissolved in a solution into an electrical potential which can be measured • Conductivity • In solution, current flows by ion transport. Therefore, an increasing ion concentration in the solution will result in higher conductivity values

  14. ICP-RESULT

  15. PH-RESULTS

  16. Conductivity-Results

  17. ISE-Results

  18. ISE-Results

  19. Solution vs. Leakers

  20. [K+] vs. Conductivity

  21. Recommendations • Further research suggested • Current data is inconclusive • Solution Monitoring Methods • Conductivity and K-ISE viable methods • Counter Current Wash Modifications

  22. Suggested Wash Flow Revision • JenFab Drum Washer Tap Water + RP Dirty Rinse Wash solution Waste Water

  23. Acknowledgements • Autoliv Inc. • Mark Bunker • Dr. David Drown • Dr. Yanko Kranov • Dr. Karl Rink • Dr. Daniel Choi • Branden Poulsen

  24. Thank you for your attention. Questions?

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