Firestone Tires

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Firestone Tires

• Parag Patel
• Joshua Pun
• Cory Robinson

2
Outline

• Introduction
• Tire Production
• Overview of Tread Separation Problem
• Legal Matters
• Conclusion/Questions

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

4
Tire Production

• Statistics
• Source http//www.rubbernews.com/subscriber/chart
  s/global.html

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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)

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Processing Production

• Mix Process Oils, Rubber, Reinforcers,
  Accelerators, Anti-Degradants
• Coatings
• Fabric
• Steel Belt
• Bead

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Processing Production (cont)

• Components taken to tire machine for assemble
• Inner liner
• Ply Fabric (two layers) possible cause of
  problem
• Apexes
• Chafer Strips
• Steel Belts
• Curing
• Inspection

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Chemistry of Tires - Introduction

• Overview of Vulcanization Process
• Description of Brass-on-Wire Adhesion
• 2nd Major Issue in Faulty Firestone Tires

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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.

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Properties

• Source Mark, James E. Science and Technology of
  Rubber. Academic San Diego, CA, 1994

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Vulcanization (cont)

• Heat with and without accelerators
• Without 5 hrs _at_ 140 oC / 8 phr sulfur
• With 1-3 min _at_ 140 oC / 0.5 phr sulfur
• Main Considerations
• Size and type of object (thick walled -gt 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)

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Mechanisms

• Source Mark, James E. Science and Technology of
  Rubber. Academic San Diego, CA, 1994

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

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Brass-on-Wire Adhesion

• Formation of Copper Sulfide Layer
• Rubber infiltration into porous CuS layer
• Prevent ZnS/FeS layers (not porous)

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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

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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

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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

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Legal Matters (cont)

• Ford Motors Corporations Position
• -stands by their design of Ford Explorers
• -changed recommended tire pressure
• Plaintiffs Position
• -continue to file lawsuits
• -boycott product manufactured by Ford and
  Firestone

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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