Firestone Tires

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					Firestone Tires

           Parag Patel
           Joshua Pun
          Cory Robinson
          CE 435 -- Intoduction to Polymers   1
Outline
l Introduction
l TireProduction
l Overview of Tread Separation Problem
l Legal Matters
l Conclusion/Questions




             CE 435 -- Intoduction to Polymers   2
 Introduction
l 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   3
    Tire Production
l   Statistics:




          Source: http://www.rubbernews.com/subscriber/charts/global.html

                           CE 435 -- Intoduction to Polymers                4
Raw Materials
l   Fabric (steel, polyester, nylon, etc.)
l   Rubber (synthetic, natural, or blends)
l   Reinforcing Chemicals (silica, resins, etc.)
l   Anti-Degradant (Ozonants, paraffin waxes)
l   Adhesion Promoters (brass, cobalt salts)
l   Curatives (cure accelerators, activators, sulfur)
l   Processing Oils (Oils, Tackifiers, Softeners)

                   CE 435 -- Intoduction to Polymers    5
Processing & Production
l   Mix Process Oils, Rubber, Reinforcers,
    Accelerators, & Anti-Degradants
l   Coatings
    – Fabric
    – Steel Belt
l   Bead




                   CE 435 -- Intoduction to Polymers   6
CE 435 -- Intoduction to Polymers   7
Processing & Production (con’t)
l   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   8
CE 435 -- Intoduction to Polymers   9
Chemistry of Tires - Introduction
l Overview   of Vulcanization Process
l Description of Brass-on-Wire
  Adhesion
l 2nd Major Issue in Faulty Firestone
  Tires



             CE 435 -- Intoduction to Polymers   10
Vulcanization
l   Process by which rubber is chemically
    crosslinked (e.g. disulfides)
l   Makes material stronger, elastic, resistant
    to solvents, and moderate heat/cold.
l   Rubber is heated in the presence of sulfur
    and accelerator.




                 CE 435 -- Intoduction to Polymers   11
 Properties




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

                             CE 435 -- Intoduction to Polymers                    12
    Vulcanization (con’t)
l   Heat with and without accelerators
    – Without: 5 hrs @ 140 oC / 8 phr sulfur
      Without
    – With: 1-3 min @ 140 oC / 0.5 phr sulfur
      With
l   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        13
Mechanisms




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

                           CE 435 -- Intoduction to Polymers                    14
Brass-on-Wire Adhesion
l Process  by which brass (CuZn)
  deposited on steel belts
l Important for proper metal/rubber
  adhesion
l Care must be taken to prevent
  oxidation of both brass and steel


             CE 435 -- Intoduction to Polymers   15
Brass-on-Wire Adhesion
l   Formation of Copper Sulfide Layer
l   Rubber infiltration into porous CuS layer
l   Prevent ZnS/FeS layers (not porous)




                 CE 435 -- Intoduction to Polymers   16
Faulty Tires
l   Brass on Wire coatings must be strictly
    monitored.
l   Coated/Uncoated wire should be kept in
    environmentally controlled conditions.
l   Free from particulate matter.
l   Employee accusations of improper
    handling
    – Poor quality control
    – Used oxidized/improperly handled wire

                 CE 435 -- Intoduction to Polymers   17
Cause of Problem
l The  Ford Motor Company
  -size of the Ford Explorer
  -recommended tire pressure too low
l Drivers of the Vehicles
  -improper maintenance of tires
  -wear and tear


              CE 435 -- Intoduction to Polymers   18
Legal Matters
l   Both Firestone and Ford are in an ongoing
    battle with the public
l   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   19
Legal Matters (con’t)
l Ford   Motors Corporation’s Position
  -stands by their design of Ford Explorers
  -changed recommended tire pressure
l Plaintiff’s   Position
  -continue to file lawsuits
  -boycott product manufactured by Ford
  and Firestone

                 CE 435 -- Intoduction to Polymers   20
Conclusions & Q/A
l Firestone liability in poor quality
  control & tread design
l Ford maintains 26 psi sufficient, but
  has changed target to 30-35 psi.

l Questions


              CE 435 -- Intoduction to Polymers   21

				
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posted:8/5/2013
language:English
pages:21
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