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Do
not heat Kocetal resin over
250 (482 )
or put it in a cylinder of over
230
(446)
for a long time (more than
30 minutes). It may cause
formaldehyde gas or discolor the
resin due to the thermal
decomposition. |
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Maintain the temperature of melt
resin below
230
(446). |
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If
not used for a long period of
time, purge the melt resin in
cylinder and stop the operation. |
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If
the operation is delayed,
maintain the cylinder
temperature around
165(329). |
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Make sure that resin are free
from moisture absorption and
contamination. |
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You can mix regrind with virgin
Kocetal resin. |
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The
mechanical properties will not change
even if you use 100% of regrind resin up
to five times repeatedly. |
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Repeated use tends to lower the
elongation, but doesn't change flow a
lot. |
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The
limit dosage of regrind resin is decided
by the color. |
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In
general, up to 30% of regrind resin is
recommended for use. |
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Large
particle of regrind can cause melting
and molding problem. |
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Because Kocetal, acetal
copolymer, has low water
absorption, it can be used after
opening. The resin also can be
used without predrying, and
isn't decomposed by absorbed
moisture. However, it may cause
silver streak or any appearance
defects. So predrying is
recommended. In particular, you
are recommended to predry and
use in these cases. |
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Parts
whose appearance is important. |
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Products that require accurate dimension |
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Mold
that has mold deposit (MD) |
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Compounded special grade and colored
grade |
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〈Drying
condition> |
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General case : Heated-air drying at
80(176)
X 3 hours or more
If period of mold cleaning is short :
Heated-air drying at
100(212)
X 3 hours or
more |
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Efficiency should be considered
before manufacturing a mold to
set the best condition for
injection molding of Kocetal,
Melt flow rate, shrinkage,
dimensional stability,
uniformity ,and ecconomic. |
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Set
the injection temperature a bit higher
than
165(329), the melting temperature of
Kocetal. |
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Stay
below
220(428) to restrain formaldehyde gas
generation caused by thermal
decomposition. |
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Generally, Increase injection velocity
for thin, multi-cavity mold, or
dimension of product is important
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but,
decrease injection velocity for thick
product to avoid void problem. |
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Set
the cooling time to the point that the
product may not deform or have plate
mark when extracting it with ejector
pin. |
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 The
chart shows the general condition of injection molding
for Kocetal resin. |
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Classification
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Unit
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Standard grade
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Reinforced grade
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Cylinder temperature
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160 ~
180
(320~356)
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170 ~
190
(338~374)
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180 ~
190
(356~374)
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190 ~
210
(374~410)
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190 ~
200
(374~392)
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200 ~
220
(392~410)
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190 ~
200
(374~392)
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200 ~
220
(392~410)
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Mold
temperature
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60 ~
80
(140~176)
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70~120
(158~248)
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Injection pressure
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First
pressure
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Kg/㎠
(PSI)
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500 ~
800
(7111.67~11378.67)
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700 ~
1,200
(9956.34~17068.01)
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Second
pressure
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Kg/㎠
(PSI)
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300 ~
500
(4267.00~7111.67)
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1,000
(14223.34)
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Back
pressure
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Kg/㎠
(PSI)
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10 ~
30
(142.23~426.70)
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20 ~
50
(284.47~711.17)
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| The chart is the
standard molding condition for Kocetal resin, and can be
differed depending on the injection machine and the
shape of product. |
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Change of material |
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Maintain the interior of
cylinder clean by using PS resin
or PE resin.
In the case of molding resin
that has different molding
temperature, make sure to clean
the cylinder. |
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Suspension of work |
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If
you suspend the operation for a
long time (one hour or more),
purge the cylinder and set the
cylinder temperature below the
melting temperature
( 165℃(329) ).
It is recommended to purge the
cylinder in case of stop. |
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