Problem
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Solution
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Screw RPM reduces or stops
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Tight the belts or replace it if broken.
Check the temperature are not low/heater not failed.
Varify Supply of Voltage
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Melting pressure buzzer
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Increase the set temperature.
Replace.
Change the screen pack.
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Temperature not reaching upto set
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Tighten connection or reconnect wires.
Mount it properly.
Or Replace
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Output decreases without change in screw speed
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Decrease Water Temp. or Increase flow of cooling water
Tighten them.
Replace.
Change the screen pack.
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Weld lines
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Increase material temperature.
Increase extruder pressure.
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Degradation
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Reduce RTD and achieve narrow RTD.
Reduce stock temperature and avoid high temperature.
Eliminating degradation promoting subs.
If degradation occurs by thermo-oxidative mechanism, air should be excluded from the extruder. This can be done by putting a nitrogen blanket on the feed hopper, vent port or at the die depending upon where air is introduced.
If the degradation occurs by chemical reaction with metal surfaces of screw and barrel, a non-corrosive material of construction has to be selected for screw and barrel.
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Air Issues
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There are a number of possible solutions to air entrapment.
Change the temperature in the solid conveying zone to achieve a more positive compacting of the solid bed.
Increase of the first barrel section reduces the air entrapment. However, in some cases, a lower temperature causes n improvement.
The temperature in the solids conveying zone are important parameters in the air entrapment process.
Analyze Both the barrel and screw temperature are important. if a screw temperature adjustment capability is available, it should definitely be used to reduce the air entrapment problem.
Now Increase in the die-head pressure to alter the pressure profile along the extruder and to hopefully achieve a more rapid compacting of the solid bed.
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