Firestone Tires Parag Patel Joshua Pun Cory Robinson

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

Outline l Introduction l Tire Production 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 l l l 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 5

Processing & Production Mix Process Oils, Rubber, Reinforcers, Accelerators, & Anti-Degradants l Coatings l – 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 2 nd Major Issue in Faulty Firestone Tires CE 435 -- Intoduction to Polymers 10

Vulcanization 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. l CE 435 -- Intoduction to Polymers 11

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

Vulcanization (con’t) l Heat with and without accelerators – Without: Without 5 hrs @ 140 o. C / 8 phr sulfur – With: With 1 -3 min @ 140 o. C / 0. 5 phr sulfur 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: Source Mark, James E. Science and Technology of Rubber. Academic: San Diego, CA, 1994 CE 435 -- Intoduction to Polymers 14

Brass-on-Wire Adhesion l Process by which brass (Cu. Zn) 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 Formation of Copper Sulfide Layer l Rubber infiltration into porous Cu. S layer l Prevent Zn. S/Fe. S layers (not porous) l CE 435 -- Intoduction to Polymers 16

Faulty Tires 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 l – 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 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 l 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