1. Banbury scheduled for the shift production- schedules are issued by Production
planning dept.
2. Chemicals are made according to spec and placed in the trolley.
3. Weighed chemicals brought near the Banbury area.
4.Two skids of compound charged to auto stock loader to ensure proper blending.
5. Rubber compounder weight master batch according to the spec.
6. Operator selects the particular recipe to be mixed .
7. Then the material is transferred from weighing conveyor to charging conveyor with
final chemical
8. Operator opens the hopper door and the material is charged toBanbury. After that
the operator closes the hopper door and switches the banbury to auto from
manual.
9. Mixing is continued as per the pre set sequence of operation anddischarged
automatically.
10. Discharged batches are handled on dump mill as per standard work instructions
and batched off from batch off mill
COMMON PROBLEMS IN MIXING
1) Dispersion
Batch size is not proper
Mixing time is insufficient
Filler addition is not in proper time
Overaged rubbers
Moisture in fillers
Insufficient ram pressure
2) Scorchiness
Loading temperature is high
Insufficient cooling during mixing
Dump temperaure is too high
Poor dispersion of vulcanising agents
Too high rotor speed
3) Contamination
Oil seepage from faulty oil seal in mixer
Contaminated ingredients
Residual compound sticking to rotor discharge door, hopper and ram
4) Poor processability at sheeter
Ineffective control of mill roll temperature and friction ratio
Mill Compound viscosity too high or too low
Poor dispersion
Too high loading of tacky fillers
Insufficient or excessive loading
High loading of tackifiers
5) Batch to Batch variation
Variation in initial loading temperature
Variation in ram pressure
Variation in dump time and temperature
Different level of dispersion
COMMON PROBLEMS AND CAUSES
Lumpy
1 Overmilling of Final batches
1. High Batch mixing temperature for
2. Batch with lower dosage of retarder.
Compound final batches.
3. Mill trays not cleaned before change
4. Curative contamination during repass
5. Master batch mooney viscosity is high
over batch mixing. and leads in to high batch temperature
6. Wrong setting of compound in selecting
7. Discharge door not opening after during final mixing.
receipe mixing final batch
8. Wrong selection of Chemical codes & error in weighment. machine.
9. Receipe selected is not accepted by
10. Lumpy w/a usage during final mixing.
11. Poor heat transfer during batch mixing
12. Refined stock with lumps.
/ milling
13. Final batch mixing at high RPM
14. Power supply off on mills.
Rheological properties Off
1. Wrong usage of chemicals, master & Identification
2. Chemical loss during mixing.
3. Wrong selection of Chemicals,
Master/ Repass stock.
4. Chemical spillage after compounding.
5. Batch on dump mill mixed with
extra chemicals falling from batch being viscosity.
6. Master Stock with less / high Mooney
chemicals falling from batch being viscosity.
7. Poor homoginisation of batch on dump
8. Batch dumped unmix due to auto
9. Master stock is with low / high Sp.
mill. failure. Gravity.
10. Blender bar not in use
11. Mixer RPM is more / less.
12. Overmilling of batch at dump & sheeting mills
13. Ram Pressure High / low
14. Master/Repass stock usage from only
15. Mixing time is low / high.
16. Wrong weighment of master/ repass
17. Process oil count is low / high.
18. Batch mixed without / extra chemicals.
19. Poor heat transfer during batch mixing
/ milling
20. Two batch loaded with single chemical
21. Wrong selection of receipe.
Specific Gravity
1. Wrong specification entry.
2. Batch dumped unmix due to auto fail.
3. Raw material sp.gr. Low / High.
4. Wrong weighment of Polymers / Chemicals /Carbon / Master stock.
5. Chemical / Carbon loss during mixing.
6. Mill trays and compound not cleared before change over.
7. Error in Polymer/Carbon/Oil weighing scale
8. Poor homoginisation of batch on dump mill.
9. Excess Dust collector suction.
10. Two batch loaded with single chemical
No comments:
Post a Comment