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The
EXTRUDER
TIMES
Published by
CONSULTANC Y SERV I CES , I ND I A
Can PVC be successfully compounded on a co-rotating TSE?
- Mr. K.Kumar, Bangalore
Traditionally, PVC has always been compounded on a conical counter machine. However
there has been regular enquiries about possibilty of getting PVC compounded in a Co-
rotating Twin-screw Extruder. The general impression is not positive because people
have not given a sincere try. There was no acceptable explanation as to why PVC can be
processed only on counter machines. Some cited reasons like "elongational mixing
action" in counters and so on. After all, PVC—though different from other
thermoplastics—is just another polymer and our belief is that it should be possible to run
it on Co-rotating TSEs, provided that the right configuration and conditions were made
available.
Fortunately, one of the user, experimented with our special assistance. We decided to
run PVC trials on the 40mm 1200rpm Co-rotating TSE at an 'application development
center'. Results were convincing and came as per expectations. In fact, we went ahead
and successfully processed, some more difficult compounds.
The learnings from our experiments are:
1. Use special screw elements—Fractional lobe Elements (STEER/Patented)
2. Running above 300rpm was difficult, but possible with more experimentations.
3. One can get a max. of 200kgs/hr—not bad at all for a 40mm machine.
4. Back-pressures were relatively high with rigids.
It is here that a 6 x D Single-screw Dump Extruder would become useful and handy. In
summary, we would say Just Go Ahead. You can 'Compound PVC’ on a Co-rotating TSE
(with an adapted machine)
- Dr.Pradeep Bakshi
on behalf of ET expert panel.
For further queries on the subject you may write to: etec@steerworld.com
Brainstorm
Reader's Queries on Extruders, Elements,
Polymer-Compounding etc are answered
by ET's Expert Group
Brainstorm invites questions -
Readers and practitioners may send their questions to
ET. The questions must state clearly the background of the problem / issue. Selected
questions with answers will appear in subsequent issues of ET. Please send your
questions to
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DROP AN ASSUMPTION
Colombus challenged the Spanish courtiers to stand
an egg on its end.
They tried but failed.
He then hard-boiled one and squashed it down.
"That's not fair". they protested, "you broke the
rules."
"Dont be silly," he replied, "you just assumed more
than you needed to."
WHAT CAN YOU LET GO OF?
WHAT UNNECESSARY ASSUMPTIONS CAN YOU
ELIMINATE?
Source: Roger von Oech's Creative Whack Pack.
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makes every effort to ensure that the ET’s contents are correct. However, we accept no responsibility for any
errors or omissions and accept no responsibility for any loss or damage caused as an effect thereof. The opinions
expressed by experts are their own and in no way reflect that of the publisher.
Printed and Published by: ET Editorial Coordinator K.S.Ram on behalf of STEER CONSULTANCY SERVICES, 290,
4th main, 4th phase, Peenya Ind. Area, Bangalore - 560 058, India.
Contact: etec@steerworld.com
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ET solicits editorial contributions by way of
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tions and extruder technology project /
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What is the difference between shear,
shear rate, and shear heating?
The best answer will be published in subsequent ET
with name and photograph of the reader. Readers
are
INVITED
to send-in their answers with/without
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The answers have to be precise and directed to the
question. Should be a minimum of 75 words and
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Any research paper relevant to the question are to
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material.
The ET expert panel, would SELECT the most
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LAST DATE to receive the entry is
Saturday, September 30, 2006.
www.extrudertimes.com
Q: What are the symptoms of high barrel-wear in a Twin Screw Extruder?
A:
1. Dispersion of material in the extrudate will be poor. This will result in increased clogging of
the filter and a resultant increase in pressure at the filter for the same level of output or run-time.
The output may have to be reduced to over come frequent filter change.
2. The Motor Power consumed (Ampere is a good indication at constant speed) will be lower
since the work done on the material is reduced. In other words, the Specific Energy will reduce
sharply.
3. Material will bleed through the vent due to excessive clearances.
Winner: Mr. Sanjay Rana of Plastichemix industries, Vadodara
Answer for ET 2
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