The document summarizes the mixing process used in a compounding department to produce rubber compounds. The process involves two passes in a Banbury mixer: a master batch process and a finish compound process. In the first pass, various ingredients like rubber, carbon black and chemicals are mixed at 135-160°C to form a homogeneous master batch. In the second pass, the master batch is remixed with curatives at 100-110°C to form the final finish compound, which is then cooled and tested before use. The mixing process takes 4-5 minutes to produce 200kg of rubber compound per batch in the heated, mechanically powered Banbury mixer.

1. COMPOUNDING DEPARTMENT
OF
Prepared By:
ZEESHAN ZAHID D-13-CH-28
3rd Year Student- Department of Chemical Engineering
Submitted To:
Mr. MOIZ SARWAR
Manager of Compounding Department
ASSIGNMENT ON MIXING PROCESS

2. MIXING PROCESS
The mixing process is a batch operation in which each batch producing 200 kilograms of
rubber compound in almost 4 to 5 minutes.
The mixer commonly known as “Banbury Mixer”. It is a heavy machine. It consist of a
mixing chamber (that has two counter rotating rotors inside). The main function of mixer is
to break down the rubber bale, chemicals and mix them with others ingredients.
Heat is generated by frictionally or externally so it cooled by water so that vulcanization
should not being.
In mixing process, some different grades of natural rubber/synthetic rubber and some
specific chemicals are required for mixing a batch of rubber compound by applying
mechanical work to the ingredients in to blend them into a homogenous substance.
Due to the proper mixing of compound and temperature factor the mixing process is done
in two passes. The 1st pass called “Master Batch” and the 2nd pass called “Finish”.
1ST PASS PROCESS:
MASTER BACTH PROCESS
 In the 1st pass process, the compounds are brought together which include
(natural rubber, synthetic rubber, carbon black and other chemical ingredients)
and mixed in the mixer.
 Each mix is then milled with additional heating to soften the batch and mix the
chemicals forming homogenous compound.
 The homogenous compound called “Mater Batch”.
 The function of chemical ingredients as accelerator, anti-oxidant, anti-ozonant,
extender, vulcanize, pigment, plasticizer, reinforcing agent, tacki fire, processing
oil and resin.
 Time, Temperature, Pressure and raw materials are factors utilized to material
composition.
 The mixing temperature in this stage in between (135 to 160) 0C.
 If the temperature is exceed from this limit then the compound can be damage.
 The pressure of the Ram on compound is 120 Psi.
FLOW CHART OF MASTER BATCH MIXING
FILLERS
RUBBERS
PALSTICIZER
S
CHEMICALS
MATER
MIXING IN
BANBURY
MIXER
DUMP
MILL/SHEETR
MILL
OPERATIONS
COOLING OF
COMPOUND
IN COOLING
LINE
BATCTH OFF
THE MATER
COMPOIND
& STORAGE

3. 2ND PASS PROCESS:
FINISH COMPOUND
 In the 2nd pass process, the master compound and curatives package is added in
this process.
 It is a final process of mixing.
 In this process, the temperature cannot exceed (from 100 t0 110) 0C.
 If the temperature is exceeded so the finish may be scorched or cured.
 Once the mixing is completed then the compound is dumped out from mixer on
the dump mill.
 From the dump mill, take out the sample of complete finish compound
and checked it in the control lab.
 If the result is “OK” so compound released and shift to concerned
areas or If the result is “NO” then compound hold in holding area and
consume as per disposition.
 After the sampling, shift this compound to sheeter mill from dump mill.
 Then sent it to cooling line for cool down the compound temperature.
 After cooling the finish compound is ready to use in different purposes.
FLOW CHART OF FINSH CMONPOUND MIXING
OK
NO
FINISH
MIXING IN
BANBURY
MIXER
CUARIVES
PACKAGE
MASTER
COMPOUND
DUMP MILL/
SHEETER
MILL
OPERATIONS
COOLING OF
COMPOUND
IN COOLING
LINE
BATCH
OFF THE
FINISH
COMPOUND
FINISH
SAMPLE FOR
TESTING
IF
RESULT
FOUIND
COMPOUND
RELEASE &
SHIFT TO
CONCERNED
ARE
COMPOUND
HOLD &
CONSUME AS
PER
DISPOSITION