CE 435 -- Intoduction to Polymers 1
Firestone TiresFirestone Tires
Parag PatelJoshua Pun
Cory Robinson
CE 435 -- Intoduction to Polymers 2
OutlineOutline
IntroductionTire ProductionOverview of Tread Separation ProblemLegal MattersConclusion/Questions
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IntroductionIntroduction
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
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Tire ProductionTire Production Statistics:
Source: http://www.rubbernews.com/subscriber/charts/global.html
Tire Sales % of Total Tire Sales % of Total(Millions $) Corp. Sales (Millions $) Corp. Sales
Bridgestone Corp.Tokyo, J apan
Michelin et Cie.Clermont-Ferrand, France
Goodyear Tire & Rubber Co.Akron, Ohio/USA
Continental A.G.Hanover, Germany
Sumitomo Rubber Industries Ltd.Kobe, J apan
Pirelli S.p.A.Milan, Italy
Yokohama Rubber Co. Ltd.Tokyo, J apan
2,408.20 70% 2193.5 70%
2,725.20 40% 3005.8 49%
3,413.80 76% 3,750.00 75%
4,900.00 50% 4,334.00 58%
11,515.60 85% 11,311.00 85%
13,500.00 92% 12,916.30 93%
1999 1998
Co./Headquarters
13,500.00 74% 12,634.80 74%
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Raw Materials 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 & ProductionProcessing & Production Mix Process Oils, Rubber, Reinforcers,
Accelerators, & Anti-Degradants Coatings– Fabric– Steel Belt
Bead
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CE 435 -- Intoduction to Polymers 8
Processing & Production (con’t)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
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Chemistry of Tires - IntroductionChemistry of Tires - Introduction
Overview of Vulcanization ProcessDescription of Brass-on-Wire
Adhesion2nd Major Issue in Faulty Firestone
Tires
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VulcanizationVulcanization
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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PropertiesProperties
SourceSource: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994
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Vulcanization (con’t)Vulcanization (con’t) Heat with and without accelerators
– WithoutWithout: 5 hrs @ 140 oC / 8 phr sulfur– WithWith: 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)
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MechanismsMechanisms
SourceSource: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994
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Brass-on-Wire AdhesionBrass-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 AdhesionBrass-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 TiresFaulty 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 ProblemCause 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 MattersLegal 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 (con’t)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
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Conclusions & Q/AConclusions & Q/A
Firestone liability in poor quality control & tread design
Ford maintains 26 psi sufficient, but has changed target to 30-35 psi.
Questions