- Pelletizers
(extruders).
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-
- There
are millions of pages written about extruders.
-
- So
we'll keep this short and strictly connected to
recycling anyway.
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- Single
screw or twin ?
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- Single
screw extruder is a pump to all extents and works
very well with all materials till you do not pretend
to get mixing.
- Very
little indeed, doesn't matter if the screw has been
provided with a "mixing section" or two.
-
- This
will only decrease production and may be give you
some problems with the venting(s).
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- If
you need mixing, the only way to go is a twin screw
extruder.
- Twin
screw has a lot of advantages compared to single
ones; unfortunately the cost of it is pretty high.
-
- This
doesn't mean it is not convenient.
- Once
again, you should run your numbers, knowing your
material and the market to see if an higher quality
product pays more and cover the higher cost of the
extruder.
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- For
recycling purposes, remember, one venting is compulsory,
two better.
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- The
extruder is also the machine that gets all the problems
lets from whatever is before it so, if your pellet
doesn't look that great, check if there is
something wrong before it.
-
- Most
of the time the extruder runs just fine but if you
feed something different that a clean plastic product,
there is no extruder in this world that can fix
the problem.
-
- Sometimes
you may want to add some additives like lubricants,
stabilizer, odorizers etc. and to do this, once
again, we do suggest a good extruder.
-
- Also,
if you go with a single extruder, with recycled
materials, size it to run your production at no
more than 80% of its total capacity; this will make
the venting to work in a much better way and keep
temperatures of the barrel under control.
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- Just
a word about die-face pelletizers:
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- Many
types around and, like in all recycling business,
choose the simple, well working one, the one with
low maintenance and troble free.
-
- You
better sleep in the night rather than go to change
the bearing of the die face cutting.
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- Do
you agree ?