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Materials and Process Selection for the Manufacturing of

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					Materials and Process Selection
  for the Manufacturing of a
         Automobile Tire

By: Zack Sokoloff, Corbin Pozar,
Kenton Kammer
Because there are several
different materials that are
involved in the process of
manufacturing a tire. We
have decided to concentrate
on the selection of the
rubbers for this process.
This includes the Tread
Area, and the side walls.
Materials Selection Parameters

 Cost
 Density
 YieldStrength (elastic limit)
 Fatigue Strength at 10^7 cycles
List of Materials that may be
suitable for tire production

 Butadiene Rubber
 Natural Rubber
 Polyisoprene Rubber
 Polyurethane Rubber
 Styrene Butadiene Rubber
Materials Comparison Chart
    Material           Butadiene Rubber (unreinforced)           Natural Rubber (unreinforced)
                       Min          Max           Avg           Min          Max            Avg
             Cost $        0.95 $       1.05 $         1.00 $       0.79 $        0.86 $         0.82
          Density        0.0329        0.034        0.03345       0.0336         0.035         0.0343
   Yield Strength         0.218          1.02         0.619          3.05          4.06         3.555
 Fatigue Strength         0.087        0.406         0.2465          1.22          1.62           1.42


    Material        Polyisoprene Rubber (unreinforced)          Polyurethane Rubber (unfilled)
                     Min           Max           Avg            Min         Max            Avg
             Cost $       1.32 $       1.45 $        1.39 $         2.20 $      2.42 $         2.31
          Density       0.0336        0.035        0.0343          0.043      0.0437        0.04335
   Yield Strength          3.34         3.74          3.54            5.8         7.4            6.6
 Fatigue Strength          1.33          1.5        1.415            2.32        2.96           2.64


    Material        Styrene Butadiene Rubber (unreinforced)
                        Min          Max           Avg
             Cost   $       0.95 $       1.05 $         1.00
          Density          0.034       0.0347       0.03435
   Yield Strength          0.203        0.435          0.319
 Fatigue Strength         0.0812        0.174         0.1276
Passenger Tire Composition
 Natural rubber 14 %
 Synthetic rubber 27%
 Carbon black 28%
 Steel 14-15%
 Fabric, fillers, accelerators, etc. 16 - 17%
 Average weight: 25 lbs
Polyisoprene Rubber will be used for the synthetic rubber
because its mechanical properties and cost fit our needs
the best.


Passenger Tire Composition by Weight and Cost

 25 lbs * 14% Natural Rubber = 3.5 lbs
 25 lbs * 27% Synthetic Rubber = 6.75 lbs
 3.5 lbs * 0.82 $/lbs Natural Rubber =
  $ 2.87
 6.75 lbs * 1.39 $/lbs Polyisoprene Rubber =
  $ 9.38
Truck Tire Composition
 Natural rubber 27%
 Synthetic rubber 14%
 Carbon black 28%
 Steel 14-15%
 Fabric, fillers, accelerators, etc. 16-17%
 Average weight: New 120 lbs
Truck Tire Composition by Weight and Cost
   120 lbs * 14% Polyisoprene Rubber = 16.8 lbs
   120 lbs * 27% Natural Rubber = 32.40 lbs
   16.8 lbs * 1.39 $/lbs Polyisoprene Rubber = $ 23.35
   32.40 lbs * 0.82 $/lbs Natural Rubber = $ 26.57
Typical Tire production
1.   Raw Materials (various types of rubber) are placed into a mixer
     and evenly combined.
2.   Then this mix is heated and rolled to form a ply (rubber strip)
3.   The plys along with wire bundles and other composites are
     formed into the typical tire shape creating a “green tire”
4.   Then the “green tire” is placed into a mold where a balloon
     (bladder) is filled with steam and cause the treads to form on the
     walls of the tire.
Process Selection Parameters
 Mass Range
 Range of section Thickness
 Tolerance
 Capital Cost (cost of avg machine)
Tire Process Selection Limits
Rolling Process
   Raw Data
Molding Process
    Raw Data
         Process Selection Chart
                                       Rolling                                  Vacuum Molding



                                      min            max             avg           min         max           avg
Mass Range (lb)                           0.22           4140        2070.11          1.76        4410      2205.88
Range of section thickness (mil)          78.7           9840        4959.35          78.7         236       157.35
Tolerance (mil)                           3.94             19.7         11.82         31.5         47.2       39.35
Capital Cost ($)                   $164,000.00   $1,640,000.00    $902,000.00   $32,800.00   $82,000.00   $57,400.00
        Cost Analysis
 Rolling Machine = $902,000.00
 Vacuum Molding Machine = $57,400.00
 Total Capital Cost ≈ $959,400.00
Manufacturing Processes –
Rolling

Rolling is an integral part of
tire manufacturing. It
produces different sections
such as sidewalls, treads
and other parts of the tire.
Rolling is also responsible
for securing all sections of
the tire together before
curing and inspection.
Manufacturing Processes –
Molding
   Molding: Tread shape
     Engraved with tread pattern and sidewall markings
      required by D.O.T.
Manufacturing Processes –
Curing
   Curing: Final step in production
      Tires get final shape and tread pattern


   Vulcanization: Adds strength to tires
      Stronger molecular bonds
How a tire is made




     http://www.youtube.com/watch?v=If5t783NZFY

				
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