Firestone Tires
Parag Patel
Joshua Pun
Cory Robinson
CE 435 -- Intoduction to Polymers
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Outline
Introduction
 Tire Production
 Overview of Tread Separation Problem
 Legal Matters
 Conclusion/Questions

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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
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Tire Production

Statistics:
1999
Co./ Headquarters
Bridgestone Corp.
Tokyo, Japan
M ichelin et Cie.
Clermont-Ferrand, France
Goodyear Tire & Rubber Co .
Akron, Ohio/USA
Continental A.G.
Hanover, Germany
Sumitomo Rubber Industries Ltd.
Kobe, Japan
P irelli S.p.A.
Milan, Italy
Yokohama Rubber Co . Ltd.
Tokyo, Japan
1998
Tire Sales
% of Total
Tire Sales
% of Total
(M illions $ )
Corp. Sales
(M illions $ )
Corp. Sales
13,500.00
74%
12,634.80
74%
13,500.00
92%
12,916.30
93%
11,515.60
85%
11,311.00
85%
4,900.00
50%
4,334.00
58%
3,413.80
76%
3,750.00
75%
2,725.20
40%
3005.8
49%
2,408.20
70%
2193.5
70%
Source: http://www.rubbernews.com/subscriber/charts/global.html
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Raw Materials






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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 (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 - 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 (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)
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Mechanisms
Source: Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994
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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 (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/A
Firestone liability in poor quality
control & tread design
 Ford maintains 26 psi sufficient, but
has changed target to 30-35 psi.


Questions
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