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MODERN TECHNIQUES IN TYRE RETREADING

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MODERN TECHNIQUES IN TYRE RETREADING Powered By Docstoc
					“MODERN TECHNIQUES IN TYRE
      RETREADING”
               Tyre Retreading

   Tread is the portion of the tyre which meets the road surface
   In the manufacture of a new tyre, approximately 20%-25% of
    the cost is incurred in mfg of the Tread and the rest in body
   Thus retreading can save a lot of costs for the user instead of
    changing the whole tyre
   Retreading is primarily done in the Truck and Bus tyre
    segment. On an average a Truck/Bus tyre is retreaded 1.5
    times.
THERE ARE TWO TYPES OF TYRE
       RETREADING
         PROCESS


   HOT PROCESS

   COLD PROCESS
    Steps in tyre retreading process
   Step 1 : INITIAL INSPECTION

   Step 2 : BUFFING

   Step 3 : TREAD PREPARATION
             AND BUILDING

   Step 4 : ENVELOPING

   Step 5 : VULCANISING

   Step 6 : FINAL INSPECTION
               COLD PROCESS

   Step 1 : INITIAL INSPECTION

             The purpose of initial inspection is to
    verify that a casing is acceptable for a retreading
    using a thorough inspection of each tyre, inside
    and outside. Identify casing injuries and
    determine if repairable. Reject or approve the
    casing for processing.
   Step 2 : BUFFING

         THE PRIMARY OBJECTIVE
    OF THE BUFFING IS TO PREPARE
    THE WORN TREAD SURFACE OF
    THE TYRE TO RECEIVE A
    RETREAD.

         THE ORIGNAL TREAD
    DESIGN AND SOME OF THE
    UNDERTREAD IS REMOVED TO
    PROVIDE THE CASING WITH THE
    REQUIRED DIMENSIONS AND
    SURFACE TEXTURE.
     Step 3 : TREAD PREPARATION AND
                  BUILDING
   BUILDING IS THE PROCESS
    OF APPLYING A
    PREMOULDED RETREAD
    OR NEW TREAD RUBBER
    TO THE BUFFED AND
    PREPARED CASING

   AN UNCURED CUSION
    GUM THAT WILL DEVELOP
    THE BONDING
    BETWEENPREMOULDED
    TREAD AND CASING IS
    APPLIED TO THE CASING
              Step 4   : ENVELOPING
   IN THE PREMOULD PROCESS
    THE UNCURED CUSHION
    COMPOUND HAS TO
    VALCUNISE WHILE THE
    PREMOULDED TREAD HAS TO
    BE KEPT IN THE POSITION.

   THEREFORE THE TYRE IS
    PUT INTO THE ENVELOPE
    WHICH PRESSES THROUGH A
    VACCUM SYSTEM THE
    PREMOULDED TREAD
    UNIFORMLY ON THE
    CUSHION AND THE CASING
                      ELECTRIC CHAMBERS
   These chambers are heated by the
    aid of electricity; they consist of
    heating elements that are resistance
    orientated.

   If no boiler is available these are
    excellent for the purpose of
    retreading, and are more trouble free
    than steam boilers

   The capacity of the chamber may
    vary from 3 to 7 , the electric chamber
    shown has a capacity of 7 tyres.

   Guages are provided on the chamber
    to see the pressure and temperature
    on the the tyres.
                         BOILER

   In this wood is used as
    the fuel to produce the
    steam.
   The boiler shown is the
    fire tube boiler
   In this boiler steam is
    generated and supplied
    to the machineries with
    the help of metal pipes.
             Step 5 : VULCANISING

             The purpose of vulcanizing is to apply
    specified heat and pressure over a period of time to
    unvulcanised rubber
            The rubber is cured to the point of best
    physical properties and maximum adhesion to the
    surrounding elements
             In the premoulded process enveloped tyre is
    put into an autoclave whereas in the moulded process
    the tyre is cured in proper tyre moulds.
          Step 6 : FINAL INSPECTION

   To ensure a quality retread each tyre passes a
    thorough inside and outside visual inspection.
    It is mandatory the tyre meets all customer and
    government regulations.
    Some retreaders are also using instrumented
    inspection like x-ray, shearographie or high
    pressure tester.
    Unacceptable tyres are rejected and scrapped.

				
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