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Understanding Firestone Tires: Production, Vulcanization, & Legal Matters

Dive into the intricacies of Firestone tire production, chemistry, and legal issues. Learn about Vulcanization, brass-on-wire adhesion, and the ongoing battle between Firestone, Ford, and the public.

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Understanding Firestone Tires: Production, Vulcanization, & Legal Matters

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  1. Firestone Tires Parag Patel Joshua Pun Cory Robinson CE 435 -- Intoduction to Polymers

  2. Outline • Introduction • Tire Production • Overview of Tread Separation Problem • Legal Matters • Conclusion/Questions CE 435 -- Intoduction to Polymers

  3. Introduction • Charles Goodyear 1800 – 1860 • 1821: Went into hardware business • 1833: Started making rubber goods • 1834: Failure in first rubber venture • 1837: Eliminated some of the rubber defects • 1838: Bought patent from partner • 1844: Discovered Vulcanization CE 435 -- Intoduction to Polymers

  4. Tire Production • Statistics: Source: http://www.rubbernews.com/subscriber/charts/global.html CE 435 -- Intoduction to Polymers

  5. Raw Materials • Fabric(steel, polyester, nylon, etc.) • Rubber(synthetic, natural, or blends) • Reinforcing Chemicals(silica, resins, etc.) • Anti-Degradant(Ozonants, paraffin waxes) • Adhesion Promoters(brass, cobalt salts) • Curatives(cure accelerators, activators, sulfur) • Processing Oils(Oils, Tackifiers, Softeners) CE 435 -- Intoduction to Polymers

  6. Processing & Production • Mix Process Oils, Rubber, Reinforcers, Accelerators, & Anti-Degradants • Coatings • Fabric • Steel Belt • Bead CE 435 -- Intoduction to Polymers

  7. CE 435 -- Intoduction to Polymers

  8. Processing & Production (con’t) • Components taken to tire machine for assemble • Inner liner • Ply Fabric (two layers) – possible cause of problem • Apexes • Chafer Strips • Steel Belts • Curing • Inspection CE 435 -- Intoduction to Polymers

  9. CE 435 -- Intoduction to Polymers

  10. Chemistry of Tires - Introduction • Overview of Vulcanization Process • Description of Brass-on-Wire Adhesion • 2nd Major Issue in Faulty Firestone Tires CE 435 -- Intoduction to Polymers

  11. Vulcanization • Process by which rubber is chemically crosslinked (e.g. disulfides) • Makes material stronger, elastic, resistant to solvents, and moderate heat/cold. • Rubber is heated in the presence of sulfur and accelerator. CE 435 -- Intoduction to Polymers

  12. Properties Source: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994 CE 435 -- Intoduction to Polymers

  13. Vulcanization (con’t) • Heat with and without accelerators • Without: 5 hrs @ 140 oC / 8 phr sulfur • With: 1-3 min @ 140 oC / 0.5 phr sulfur • Main Considerations: • Size and type of object (thick walled -> longer curing time) • Compound vulcanizabliity and flowability • Type of vulcanization (mould vs. boiler) • Maximum vulcanization temperature of material or system • Removal of article from mould (higher temp, more difficult) CE 435 -- Intoduction to Polymers

  14. Mechanisms Source: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994 CE 435 -- Intoduction to Polymers

  15. Brass-on-Wire Adhesion • Process by which brass (CuZn) deposited on steel belts • Important for proper metal/rubber adhesion • Care must be taken to prevent oxidation of both brass and steel CE 435 -- Intoduction to Polymers

  16. Brass-on-Wire Adhesion • Formation of Copper Sulfide Layer • Rubber infiltration into porous CuS layer • Prevent ZnS/FeS layers (not porous) CE 435 -- Intoduction to Polymers

  17. Faulty Tires • Brass on Wire coatings must be strictly monitored. • Coated/Uncoated wire should be kept in environmentally controlled conditions. • Free from particulate matter. • Employee accusations of improper handling • Poor quality control • Used oxidized/improperly handled wire CE 435 -- Intoduction to Polymers

  18. Cause of Problem • The Ford Motor Company -size of the Ford Explorer -recommended tire pressure too low • Drivers of the Vehicles -improper maintenance of tires -wear and tear CE 435 -- Intoduction to Polymers

  19. Legal Matters • Both Firestone and Ford are in an ongoing battle with the public • Bridgestone/Firestone Position -taken the responsibility for faulty design -initiated world wide recall -offered free replacements -still believe blame should not wholly be on them CE 435 -- Intoduction to Polymers

  20. Legal Matters (con’t) • Ford Motors Corporation’s Position -stands by their design of Ford Explorers -changed recommended tire pressure • Plaintiff’s Position -continue to file lawsuits -boycott product manufactured by Ford and Firestone CE 435 -- Intoduction to Polymers

  21. Conclusions & Q/A • Firestone liability in poor quality control & tread design • Ford maintains 26 psi sufficient, but has changed target to 30-35 psi. • Questions CE 435 -- Intoduction to Polymers

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