Common problems in Waste plastic granulating processing and how to solve?

Common problems in Waste plastic granulating processing and how to solve?
2017-11-14 14:59:00

1. A series of pellets which are attached to each other, we often called doubles or plastic pellets zippers

Pellets zipper
Reason:
1)Water temperature for cooling is too high
2)Water flow speed is too slow which will reduce the speed of pelletizer
3)The distance of mold hole is too close. During the extruding, the pellets will be expanded and touch with each other
Solve:
1)Low down the water temperature to make the pellets cooled enough
2)Keep the water speed to
3)Change the mold and adopt the widely spaced with less hole

2. Among the most commonly encountered problem in plastic pelletizing/ granulating are tails (Pellets protrusions)

Pellets protrusions
Reasons:
1)Cutting system.
Solve:
1)To the Pull strips pelletizing type:
▶ Change the New Rotary blades and Stable blades
▶ Adjust the machine space as manufacture’s instructions
2)To the Water-ring pelletizing or underwater pelletizing type
▶ Check the mold and watering cutting blades to make sure there are no nick

3. Shrink hollow pellets

Reasons:
1)Cooling water is too hot or too cold which will make the plastic strip cooled outside but heat inside
2)Too much moisture
Solve:
1)Dry the raw material before pelletizing
2)Keep the degassing part on the extruder barrel clear
3)Control the temperature of cooling water to keep sure the pellets can evaporative the water on the surface of pellets.

4. Strips broken (Pull strips and pelletizing type)
▶ Increase the quantity or mesh of filter screen
▶ Appropriate reduction of main extruder rotating speed or make higher speed of Feeder
▶ Low down the extruder heating temperature (Machine head or other heating zones)

4.1 External impurities
▶ Increase the quantity or mesh of filter screen
▶ Try to cover the holes that might drop debris (Covered by net or others)
▶ To check whether it is cleaned enough during Mixer and Discharger system (Note the blind corner of the machine)

4.2 Inner impurities
▶ Machine head pressure of extruder is too high
---- Die blocked up
---- Quantity of Filter screen is too many
---- Machine head temperature is too low
▶ Over heated in parts of extruder will cause carbonation aggravated, the carbonization will be mixed with plastic strips. The strips will be broken under the action of traction
▶ Parts of screw shearing strength is too strong, which will cause material carbonated. The carbonization will be mixed with plastic strips. The strips will be broken under the action of traction
▶ The screw and barrel is worn after time using, the space becomes larger, flow rate increased, the carbonization on the surface of barrel increased. The carbonization will be mixed with plastic strips as the extruding time goes longer. The strips will be broken under the action of traction
▶ Vacuum or Normal degassing part: long time no cleaning.
The carbonization will be mixed with plastic strips. The strips will be broken under the action of traction
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Business scope:
PET Granulating/Pelletizing machine line
Agricultural film Cutting, Washing, Drying & Granulating machine line
Jumbo bag Recycling & Granulating machine line
PP/PE Recycling & Granulating machine line

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