tips for defect-free injection molding of tpu - mito polimeri for defect free injection...
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2 1
Tips for Defect-Free Injection Molding of TPU
Covestro Deutschland AGCHEMPARK DormagenAlte HeerstraßeBuilding F2941538 Dormagene-mail: [email protected]
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This information and our technical advice – whether verbal, in writing or by ways of trial – are given in good faith but without warranty, and this also applies where pro-prietary rights of third parties are involved. The information is provided by Covestro without assumption of any liability. If any of the above mentioned regulations change after the date of declaration, this dec laration is no longer valid. Covestro will strive to keep this information up-to-date. Our advice does not release you from the obliga-tion to verify the information provided – especially that contained in our safety data and technical information sheets –, to check for updates of any information provided by us and to test our products as to their suitability for the intended processes and uses. The application, use and processing of our products and the products manu-factured by you on the basis of our technical advice are beyond our control and, therefore, entirely your own responsibility. Our products are sold in accordance with the current version of our General Conditions of Sale and Delivery.
Edition: 2016 · Order-No.: COV00080632 · Printed in Germany
2 3
Vario
us p
robl
ems
can
aris
e w
hen
inje
ctio
n m
oldi
ng t
herm
opla
stic
s –
and
that
goe
s fo
r TP
U, to
o. W
e ha
ve c
ompi
led
an e
xten
sive
list
of
pos
sibl
e de
fect
s, e
xpla
ined
the
ir ca
uses
an
d de
scrib
ed p
reve
ntiv
e m
easu
res.
To
help
yo
u fin
d th
em m
ore
easi
ly, w
e ha
ve d
ivid
ed
the
defe
cts
into
gro
ups,
suc
h as
“D
efec
ts
caus
ed b
y w
arpa
ge” a
nd “D
efec
ts c
ause
d by
sp
ecks
and
dot
s”. P
leas
e do
not
hes
itate
to
cont
act u
s if
this
list
doe
s no
t hel
p yo
u so
lve
your
pro
blem
. W
e w
ould
be
grat
eful
for
any
hint
s, s
ugge
s-tio
ns a
nd i
llust
ratio
ns y
ou c
ould
sub
mit
to
mak
e th
is c
atal
ogue
of
defe
cts
mor
e co
m-
plet
e.
Tip
s fo
r def
ect-
free
inje
ctio
n m
oldi
ng o
f TPU
1. 1.
1 De
fect
s in
dim
ensi
ons
41.
2 De
mol
ding
def
ects
9
1.3
Colo
r def
ects
16
1.4
Defe
cts
in th
e fo
rm o
f spe
cks
and
dots
24
1.5
Unev
enne
ss d
efec
ts
251.
6 Pr
oces
sing
def
ects
31
1.7
War
page
def
ects
34
1.8
Glo
ss d
efec
ts
351.
9 De
fect
s in
mec
hani
cal p
rope
rtie
s 44
1.10
Sur
face
def
ects
47
4 5
Caus
es:
Rem
edie
s:
Unsu
itabl
e pr
oces
sing
par
amet
ers
Opt
imize
pro
cess
ing
para
met
ers.
Incr
ease
mel
t an
d m
old
tem
pera
ture
s. In
crea
se in
ject
ion
spee
d.
Switc
h to
hol
ding
pre
ssur
e at
a la
ter p
oint
in ti
me
Pres
sure
loss
es to
o hi
gh in
gat
ing
syst
em, in
clud
-in
g ho
t run
ner.
Spru
e, g
ate
and
runn
er c
ross
-sec
-tio
ns to
o sm
all. P
ress
ure
loss
in h
ot ru
nner
too
high
. Pre
ssur
e lo
ss in
shu
t-off
noz
zle s
yste
m to
o hi
gh
Redu
ce p
ress
ure
loss
es in
gat
ing
syst
em. In
crea
se
spru
e, g
ate
and
runn
er c
ross
-sec
tions
. Che
ck h
ot
runn
er c
ross
-sec
tions
, opt
imize
noz
zle p
oint
tor-
pedo
. Wor
k w
ith m
achi
ne n
ozzle
ope
n
Wal
l thi
ckne
ss in
adeq
uate
Incr
ease
wal
l thi
ckne
ss
Caus
es:
Rem
edie
s:
Perm
itted
gap
wid
th e
xcee
ded.
Loc
king
forc
e
inad
equa
te. M
old
rigid
ity in
adeq
uate
. Wea
r of
seal
ing
face
s
Chec
k ga
p w
idth
s.
Incr
ease
lock
ing
forc
e. In
crea
se m
old
rigid
ity.
Rew
ork
seal
ing
face
s
Proc
essi
ng p
aram
eter
s no
t opt
imize
dO
ptim
ize p
roce
ssin
g pa
ram
eter
s. R
educ
e in
ject
ion
spee
d or
mel
t tem
pera
ture
. Sw
itch
to h
oldi
ng
pres
sure
ear
lier o
r red
uce
hold
ing
pres
sure
Sho
rt m
oldi
ng
1.1
Def
ects
in d
imen
sion
s
Des
crip
tion:
Mol
ding
not
com
plet
ely
fille
d, m
ostly
at e
nd o
f flow
pat
h or
th
in-w
alle
d lo
catio
ns
Des
crip
tion:
Mol
d ga
p re
sults
in p
olym
er m
elt p
enet
ratio
n on
mol
ding
Fla
sh
6 7
Caus
es:
Rem
edie
s:
Mat
eria
l too
moi
stCh
eck
mat
eria
l’s d
ryne
ss
Pred
icte
d sh
rinka
ge in
corre
ct
Chec
k sh
rinka
ge c
alcu
latio
n
usin
g de
tails
from
raw
mat
eria
l m
anuf
actu
rer o
r com
para
ble
m
olds
War
page
due
to u
nsui
tabl
e de
sign
of p
art o
r ga
te p
ositi
on
Chec
k m
oldi
ng fo
r war
page
and
sw
itch
to lo
w-
war
page
des
ign.
Cha
nge
gate
pos
ition
to o
btai
n un
iform
orie
ntat
ion
Mac
hine
and
mol
d no
t in
ther
mal
equ
ilibriu
mCh
eck
tem
pera
ture
pro
file
of m
achi
ne a
nd m
old
for
ther
mal
fluc
tuat
ions
Wei
ght v
aria
tion
Var
iatio
ns in
siz
e
Des
crip
tion:
Sig
nific
ant fl
uctu
atio
ns in
mol
ded
part
wei
ght a
nd m
ass
Des
crip
tion:
Req
uire
d di
men
sion
s of
par
t not
ach
ieve
d
actual
target
Caus
es:
Rem
edie
s:
Wea
r in
plas
ticat
ing
unit
Chec
k pl
astic
atin
g un
it –
in p
artic
ular
non
-ret
urn
valv
e –
for w
ear
Mol
d an
d m
elt t
empe
ratu
re fl
uctu
atio
nsCh
eck
plas
ticat
ing
unit’
s te
mpe
ratu
re c
ontro
l un
its a
nd h
eatin
g ci
rcui
ts
Dryi
ng in
adeq
uate
Chec
k dr
ying
pro
cess
Met
erin
g st
roke
or m
elt c
ushi
on fl
uctu
ates
Chec
k in
ject
ion
mol
ding
mac
hine
’s in
ject
ion
and
m
eter
ing
stro
ke
Lock
ing
forc
e in
adeq
uate
Incr
ease
set
lock
ing
forc
e or
sel
ect m
achi
ne w
ith
high
er lo
ckin
g fo
rce
8 9
Caus
es:
Rem
edie
s:
Mol
d rig
idity
inad
equa
teCh
eck
mol
d rig
idity
and
rein
forc
e m
old
if
nece
ssar
y
Shrin
kage
allo
wan
ce in
accu
rate
, mol
d di
men
sion
s in
corre
ctCh
eck
mol
d di
men
sion
s, c
ompa
re w
ith ra
w
mat
eria
l man
ufac
ture
r’s s
hrin
kage
dat
a
Cavi
ty p
ress
ure
too
high
or l
ocki
ng fo
rce
too
low
Redu
ce c
avity
pre
ssur
e by
sw
itchi
ng to
hol
ding
pr
essu
re e
arlie
r or u
sing
a lo
wer
hol
ding
pre
ssur
e
and
incr
ease
lock
ing
forc
e
Mol
d ce
nter
ing
devi
ce d
efec
tive
or w
orn
Chec
k m
old
cent
erin
g de
vice
and
repl
ace
if
nece
ssar
y
Caus
es:
Rem
edie
s:
Unsu
itabl
e pr
oces
sing
par
amet
ers
(poi
nt a
t whi
ch
switc
h is
mad
e fro
m in
ject
ion
to h
oldi
ng p
ress
ure,
le
vel o
f hol
ding
pre
ssur
e)
Opt
imize
pro
cess
ing
para
met
ers.
Red
uce
cavi
ty
pres
sure
by
switc
hing
to h
oldi
ng p
ress
ure
earli
er
and
usin
g a
low
er h
oldi
ng p
ress
ure.
Che
ck c
oolin
g tim
e an
d in
crea
se if
nec
essa
ry
Nozz
le ra
dius
or a
pert
ure
too
larg
eRe
duce
noz
zle ra
dius
or a
pert
ure
Draf
ts a
nd p
olis
hing
inad
equa
te
Chec
k co
mpo
nent
s su
ch a
s m
achi
ne n
ozzle
, col
d ru
nner
and
gat
e fo
r und
ercu
ts a
nd p
olis
hing
and
re
wor
k in
the
dire
ctio
n of
rem
oval
(dem
oldi
ng) if
ne
cess
ary.
Opt
imize
dra
fts a
nd p
olis
h if
nece
ssar
y
Des
crip
tion:
Thi
ckne
ss o
f mol
ded
part
doe
s no
t cor
resp
ond
to n
omin
al
valu
e or
var
ies
grea
tly a
nd is
not
with
in to
lera
nce
rang
e
1.2
Dem
oldi
ng d
efec
ts
Des
crip
tion:
Spr
ue c
ontra
cts
and
/ or r
emai
ns a
ttach
ed to
spr
ue
bush
or c
old
runn
er
Var
iatio
ns in
wal
l thi
ckne
ss
(de
viat
ion
betw
een
nom
inal
and
act
ual v
alue
s)
Spr
ue re
mai
ns a
ttac
hed
10 11
Caus
es:
Rem
edie
s:
Cavi
ty p
ress
ure
too
high
Opt
imize
inje
ctio
n sp
eed.
Red
uce
hold
ing
pres
sure
. Sw
itch
to h
oldi
ng p
ress
ure
earli
er
Mol
d rig
idity
inad
equa
teIm
prov
e m
old
rigid
ity
Inad
equa
te c
oolin
g tim
e or
mol
d te
mpe
ratu
re
loca
lly to
o hi
ghO
ptim
ize c
oolin
g / m
old
tem
pera
ture
con
trol
Unsu
itabl
e m
old
desi
gn. E
xces
sive
und
ercu
ts,
inad
equa
te d
raft
Opt
imize
mol
d de
sign
. Red
uce
unde
rcut
s,
optim
ize d
rafts
Inad
equa
te m
old
(cav
ity) p
olis
hing
. Eje
ctor
pos
ition
un
suita
ble
or e
ject
or a
rea
too
smal
lIm
prov
e m
old
(cav
ity) p
olis
hing
. Opt
imize
eje
ctor
po
sitio
n or
enl
arge
eje
ctor
are
a
Caus
es:
Rem
edie
s:
Draf
ts in
adeq
uate
Chec
k m
old
polis
hing
and
dra
fts, r
ewor
k if
ne
cess
ary.
Use
an a
ppro
pria
te m
old
rele
ase
agen
t
Mol
d ce
nter
ing
devi
ce u
nsui
tabl
e or
wor
nIm
prov
e m
old
cent
erin
g
Cavi
ty p
ress
ure
too
high
Redu
ce c
avity
pre
ssur
e. S
witc
h fro
m in
ject
ion
to
hold
ing
pres
sure
ear
lier.
Redu
ce h
oldi
ng p
ress
ure
Mol
d rig
idity
inad
equa
teIn
crea
se m
old
rigid
ity
Insu
ffici
ent r
elea
se a
gent
Use
rele
ase
agen
t bat
ch
Des
crip
tion:
Dis
tinct
eje
ctor
mar
ks o
n m
oldi
ng
Des
crip
tion:
Ope
ning
the
mol
d ge
nera
tes
a co
nsid
erab
le a
mou
nt o
f noi
se
Eje
ctor
mar
ks
Noi
ses
as m
old
open
s
12 13
Des
crip
tion:
Par
t dam
aged
dur
ing
rem
oval
Caus
es:
Rem
edie
s:
Cavi
ty p
ress
ure
too
high
Opt
imize
inje
ctio
n sp
eed.
Red
uce
hold
ing
pres
sure
. Sw
itch
to h
oldi
ng p
ress
ure
earli
er
Mol
d rig
idity
inad
equa
teIm
prov
e m
old
rigid
ity
Inad
equa
te c
oolin
g tim
e or
mol
d te
mpe
ratu
re
loca
lly to
o hi
ghO
ptim
ize c
oolin
g / m
old
tem
pera
ture
con
trol
Unsu
itabl
e m
old
desi
gn. E
xces
sive
und
ercu
ts,
inad
equa
te d
raft
Opt
imize
mol
d de
sign
. Red
uce
unde
rcut
s,
optim
ize d
rafts
Inad
equa
te m
old
(cav
ity) p
olis
hing
. Eje
ctor
pos
ition
un
suita
ble
or e
ject
or a
rea
too
smal
l
Polis
h m
old
surfa
ce in
dire
ctio
n of
rem
oval
(d
emol
ding
), sel
ect a
ppro
pria
te c
oatin
g or
roug
h-ne
ss h
eigh
t. Im
prov
e po
sitio
n an
d si
ze o
f eje
c-to
rs (in
par
ticul
ar, lo
cate
nea
r cor
ners
or u
nder
rib
s / d
omes
)
Inad
equa
te m
ater
ial d
ryin
g, re
side
nce
time
to
o lo
ngCh
eck
mat
eria
l dry
ing,
resi
denc
e tim
e an
d m
elt
tem
pera
ture
Par
t fra
ctur
es d
urin
g re
mov
al
Caus
es:
Rem
edie
s:
Cavi
ty p
ress
ure
too
high
Redu
ce c
avity
pre
ssur
e. S
witc
h fro
m in
ject
ion
to
hold
ing
pres
sure
ear
lier.
Redu
ce h
oldi
ng p
ress
ure.
In
crea
se m
elt t
empe
ratu
re w
ithin
per
mitt
ed lim
its
Mol
d rig
idity
inad
equa
teIn
crea
se m
old
rigid
ity
Slid
e va
lve
cont
rol f
ailu
reCh
eck
slid
e va
lve
is in
cor
rect
pos
ition
Tips
for o
peni
ng m
old:
Use
col
d w
ater
to re
duce
te
mpe
ratu
re o
f mol
d to
room
tem
pera
ture
, fit
addi
tiona
l hyd
raul
ic ra
ms
betw
een
mac
hine
pl
aten
s to
hel
p op
en m
old.
If n
eces
sary
, rai
se
mol
d te
mpe
ratu
re a
bove
gla
ss tr
ansi
tion
tem
pera
-tu
re, p
ull m
old
apar
t
Des
crip
tion:
Eve
n w
hen
appl
ying
max
imum
per
mitt
ed o
peni
ng fo
rce,
inje
ctio
n
mol
ding
mac
hine
fails
to p
ull t
wo
halv
es o
f mol
d ap
art
Mol
d fa
ils to
ope
n
14 15
Caus
es:
Rem
edie
s:
Mol
d ov
erlo
aded
Redu
ce in
ject
ion
spee
d an
d ho
ldin
g pr
essu
re
and
switc
h to
hol
ding
pre
ssur
e ea
rlier
Exce
ssiv
e un
derc
uts,
inad
equa
te d
rafts
Redu
ce u
nder
cuts
, impr
ove
draf
ts
Inad
equa
te m
old
polis
hing
on
flang
es,
ribs
or s
tuds
Polis
h m
old
surfa
ce in
dire
ctio
n of
rem
oval
(d
emol
ding
)
Vacu
um b
etw
een
mol
d su
rface
and
mol
ding
Opt
imize
mol
d ve
ntin
g
Prem
atur
e ej
ectio
n, m
olde
d pa
rt s
ticks
or s
till
too
soft
Incr
ease
coo
ling
time,
redu
ce m
old
tem
pera
ture
Ejec
tor p
ins
too
few
in n
umbe
r or p
oorly
po
sitio
ned
Incr
ease
num
ber o
f eje
ctor
pin
s or
opt
imize
thei
r po
sitio
n
Des
crip
tion:
Mol
ded
part
jam
s, c
ores
/ ej
ecto
rs d
efor
m o
r pen
etra
te p
art
Mol
ded
part
rem
ains
in c
avity
Caus
es:
Rem
edie
s:
Cavi
ty p
ress
ure
too
high
Opt
imize
inje
ctio
n sp
eed.
Red
uce
hold
ing
pr
essu
re. S
witc
h to
hol
ding
pre
ssur
e ea
rlier
Mol
d rig
idity
inad
equa
teIm
prov
e m
old
rigid
ity
Inad
equa
te c
oolin
g tim
e or
mol
d te
mpe
ratu
re to
o hi
gh lo
cally
Opt
imize
coo
ling
/ mol
d te
mpe
ratu
re c
ontro
l
Unsu
itabl
e m
old
desi
gn. E
xces
sive
und
ercu
ts,
inad
equa
te d
raft
Opt
imize
mol
d de
sign
. Red
uce
unde
rcut
s,
optim
ize d
rafts
Inad
equa
te m
old
(cav
ity) p
olis
hing
. Eje
ctor
po
sitio
n un
suita
ble
or e
ject
or a
rea
too
smal
l
Polis
h m
old
surfa
ce in
dire
ctio
n of
rem
oval
(de-
mol
ding
), sel
ect a
ppro
pria
te c
oatin
g or
roug
h-ne
ss h
eigh
t. Im
prov
e po
sitio
n an
d si
ze o
f eje
c-to
rs (in
par
ticul
ar, lo
cate
nea
r cor
ners
or u
nder
rib
s / d
omes
)
Des
crip
tion:
Par
t def
orm
ed d
urin
g re
mov
al
Par
t def
orm
ed d
urin
g re
mov
al
16 17
Caus
es:
Rem
edie
s:
Pigm
ent s
epar
atio
n or
refra
ctiv
e eff
ect d
ue to
un
suita
ble
flow
at w
eld
lines
Vary
flow
fron
t spe
ed
Ove
rhea
ting
of m
elt,
resu
lting
in c
olor
cha
nges
at
wel
d lin
esRe
duce
ther
mal
mel
t loa
d
Oxi
datio
n du
e to
inad
equa
te v
entin
g
Impr
ove
vent
ing,
if n
eces
sary
by
relo
catin
g
wel
d lin
e
N.B
.:Fa
ult t
ends
to o
ccur
on
light
, brig
ht c
olor
s su
ch
as w
hite
, blu
e, g
reen
and
ora
nge.
Des
crip
tion:
Col
ored
stri
pe. D
arke
r col
or o
ccur
s at
wel
d lin
es o
r nea
r le
adin
g / l
aggi
ng fl
ow fr
onts
fed
from
nei
ghbo
ring
mel
t stre
ams
1.3
Col
or d
efec
ts
Dar
ker c
olor
at w
eld
lines
Caus
es:
Rem
edie
s:
Mel
t tem
pera
ture
too
high
Chec
k m
elt t
empe
ratu
re a
nd re
duce
if n
eces
sary
Inad
equa
te u
tiliza
tion
of p
last
icat
ing
unit
capa
city
, re
sulti
ng in
exc
essi
ve re
side
nce
time
Use
smal
ler p
last
icat
ing
unit
Mas
ter b
atch
uns
uita
ble
Use
suita
ble
mas
ter b
atch
Prod
uctio
n st
oppa
ge w
ithou
t red
uctio
n in
te
mpe
ratu
reCo
mpl
y w
ith in
stru
ctio
ns fo
r pro
duct
ion
stop
page
Des
crip
tion:
Uni
form
dev
iatio
n fro
m b
asic
col
or, e
spec
ially
with
light
col
ors
Hom
ogen
eous
dis
colo
ratio
n
18 19
Caus
es:
Rem
edie
s:
Mat
eria
l not
ade
quat
ely
hom
ogen
ized
Incr
ease
bac
k pr
essu
re, r
educ
e sc
rew
spe
ed
Inje
ctio
n an
d sc
rew
spe
eds
too
high
Redu
ce in
ject
ion
and
scre
w s
peed
s
Gat
e to
o na
rrow
Wid
en g
ate
Resi
denc
e tim
e to
o lo
ngSh
orte
n re
side
nce
time
by s
elec
ting
smal
ler
plas
ticat
ing
unit
Des
crip
tion:
Par
tial c
hang
e in
col
or
Par
tial c
olor
cha
nge
Caus
es:
Rem
edie
s:
Mel
t flow
sta
gnat
es in
mol
d, m
elt t
empe
ratu
re
too
low
Try
to a
chie
ve e
ven
mel
t flow
, incr
ease
mel
t te
mpe
ratu
re
Mol
d te
mpe
ratu
re to
o lo
wIn
crea
se m
old
tem
pera
ture
Inad
equa
te in
ject
ion
spee
dIn
crea
se in
ject
ion
spee
d
Des
crip
tion:
Rin
gs, b
loom
effe
ct, m
atte
ring
s ru
nnin
g co
ncen
trica
lly to
gat
e
Rin
gs
20 21
Caus
es:
Rem
edie
s:
Entra
pped
, com
pres
sed
air i
n in
ject
ion
mol
d,
resu
lting
in b
urns
Opt
imize
mol
d ve
ntin
g, in
par
ticul
ar n
ear fl
ow lin
es
and
at e
nd o
f flow
pat
h. C
orre
ct fl
ow fr
ont (
wal
l th
ickn
ess,
gat
e po
sitio
n or
flow
pro
mot
ers)
. Che
ck
vent
ing
chan
nels
. Red
uce
clam
ping
forc
e. E
vacu
ate
mol
d
Des
crip
tion:
Stre
aks
and
stai
ns fr
om b
urni
ng, p
erio
dic
disc
olor
atio
n,
dark
spo
ts. B
row
n to
bla
ck d
isco
lora
tion
of m
oldi
ng, a
t diff
eren
t loc
atio
ns
and
irreg
ular
dis
tanc
es
Bla
ck (o
verh
eatin
g) m
arks
Caus
es:
Rem
edie
s:
Unfa
vora
ble
cros
s-se
ctio
n ch
ange
s / b
ends
or
defe
ctiv
e se
alin
g fa
ces,
resu
lting
in d
ead
spot
s w
here
mat
eria
l bur
ns. D
ead
spot
s at
sea
ling
face
s,
cros
s-se
ctio
n ch
ange
s or
ben
ds in
hot
runn
e
Chec
k / r
ewor
k pa
rts
and
seal
ing
face
s aff
ecte
d.
Elim
inat
e de
ad s
pots
. Che
ck w
eep
hole
s fo
r nee
dle
valv
e sy
stem
. Che
ck s
ealin
g fa
ces.
Che
ck d
irect
ion
chan
ges
and
trans
ition
con
e
Scre
w, n
on-r
etur
n va
lve
or c
ylin
der w
ear
Chec
k sc
rew,
non
-ret
urn
valv
e an
d cy
linde
r for
w
ear
N.B
.:In
add
ition
to o
ptic
al d
egra
datio
n of
the
mol
ded
part
, thi
s fa
ult c
an a
lso
dam
age
the
mol
d th
roug
h co
rrosi
on.
Des
crip
tion:
Die
sel e
ffect
. Con
cent
rate
d bl
ack
colo
ring
at p
oint
s w
here
flo
ws
mer
ge, e
.g. o
n fla
nges
or s
tuds
or i
n co
rner
s at
end
of fl
ow p
aths
Bla
ck d
isco
lora
tion
22 23
Caus
es:
Rem
edie
s:
Ove
rstre
tchi
ng o
f pol
ymer
mat
rix. D
emol
ding
ca
uses
exc
essi
ve m
echa
nica
l stre
ss. E
ject
or p
ins
poor
ly p
ositi
oned
and
dra
fts in
adeq
uate
Redu
ce m
echa
nica
l stre
ss d
urin
g de
mol
ding
. Po
sitio
n ej
ecto
r pin
s ne
ar c
orne
rs, d
omes
and
ribs
(in
gen
eral
at s
tress
-whi
tene
d lin
es)
Exce
ssiv
e se
rvic
e lo
adAd
apt s
ervi
ce lo
ads
to m
ater
ial v
alue
s
Cavi
ty p
ress
ure
too
high
. Mol
d rig
idity
inad
equa
te
Redu
ce c
avity
pre
ssur
e. In
crea
se m
old
rigid
ity
N.B
.:Fa
ult m
ostly
occ
urs
with
ther
mop
last
ics
co
ntai
ning
rubb
er.
Des
crip
tion:
Lig
hter
col
or in
pla
ces,
with
velve
ty m
oldi
ng s
urfa
ce
Str
ess-
whi
teni
ng
Caus
es:
Rem
edie
s:
Plas
ticat
ing
unit
dirt
yCl
ean
plas
ticat
ing
unit.
Re
duce
scr
ew s
peed
Wea
r effe
cts
on p
last
icat
ing
unit
Repl
ace
entir
e un
it or
in
divi
dual
(wor
n) c
om -
pone
nts.
Use
a p
last
icat
ing
unit
with
an
abra
sion
- an
d co
rrosi
on-r
esis
tant
coa
ting
Des
crip
tion:
Gra
y st
reak
s. M
oldi
ng s
urfa
ce h
as d
ark,
clo
udy
appe
aran
ce
Clo
udy
appe
aran
ce
24 25
Caus
es:
Rem
edie
s:
Boun
dary
laye
rs th
at h
ave
form
ed o
n sc
rew
/
cylin
der s
urfa
ce d
amag
ed /
flaki
ng o
ff
Clea
n pl
astic
atin
g un
it m
echa
nica
lly. C
ompl
y
with
pro
cedu
res
for p
rodu
ctio
n st
oppa
ges.
Ch
eck
plas
ticat
ing
unit
for w
ear
Soilin
g of
gra
nule
s or
regr
anul
ated
scr
ap
Chec
k cl
eann
ess
of g
ranu
les.
Sto
re g
ranu
les
in
a du
st-f
ree
loca
tion.
Cle
an s
oile
d m
oldi
ngs
prio
r to
regr
anul
atio
n. D
o no
t reg
ranu
late
moi
st o
r th
erm
ally
dam
aged
mol
ding
s. C
heck
dry
ing
and
conv
eyor
sys
tem
for s
oilin
g
1.4
Def
ects
in th
e fo
rm o
f spe
cks a
nd d
ots
Des
crip
tion:
Spe
cks,
eith
er s
pher
ical
with
irre
gula
r con
tour
s or
flak
y
with
sha
rp, li
near
con
tour
s, o
ccur
ring
spor
adic
ally
Bla
ck o
r bro
wn
dots
Des
crip
tion:
Hig
hly
loca
lized
roun
d or
elo
ngat
ed s
olid
sw
ellin
gs –
hor
izont
al o
r ver
tical
–
on m
olde
d pa
rt, n
ot n
eces
saril
y di
scer
nibl
e on
bot
h si
des
1.5
Une
venn
ess
defe
cts
Caus
es:
Rem
edie
s:
Unm
elte
d m
ater
ial o
r air
inta
ke d
urin
g m
eter
ing,
sc
rew
cut
too
deep
lyUs
e ap
prop
riate
scr
ew
Unm
elte
d m
ater
ial o
r air
inta
ke d
urin
g m
eter
ing,
m
eter
ing
stro
ke g
reat
er th
an 3
D (D
= d
iam
eter
)Se
lect
met
erin
g st
roke
bet
wee
n 1
and
3 D
Unm
elte
d m
ater
ial o
r air
inta
ke d
urin
g m
eter
ing,
ba
ck p
ress
ure
inad
equa
teIn
crea
se b
ack
pres
sure
Unm
elte
d m
ater
ial o
r air
inta
ke d
urin
g m
eter
ing,
m
elt t
empe
ratu
re to
o lo
wIn
crea
se m
elt t
empe
ratu
re
Unm
elte
d m
ater
ial o
r air
inta
ke d
urin
g m
eter
ing,
sc
rew
spe
ed to
o hi
ghRe
duce
scr
ew s
peed
Poc
kets
26 27
Caus
es:
Rem
edie
s:
Exce
ssiv
e sh
ear s
tress
. Gat
e to
o na
rrow.
In
ject
ion
spee
d to
o hi
ghRe
duce
she
ar s
tress
. Wid
en g
ates
. Red
uce
in
ject
ion
spee
d
Cont
amin
atio
n by
inco
mpa
tible
resi
nsCl
ean
plas
ticat
ing
unit.
Che
ck m
ater
ial in
hop
per
and
ma t
eria
l sup
ply
syst
em fo
r con
tam
inat
ion
by
othe
r mat
eria
ls
Colo
r bat
ch u
nsui
tabl
eUs
e ap
prop
riate
col
or b
atch
Caus
es:
Rem
edie
s:
No c
ompe
nsat
ion
for v
olum
e co
ntra
ctio
n du
ring
cool
ing
phas
e
Com
pens
ate
for v
olum
e co
ntra
ctio
n by
ada
ptin
g w
all t
hick
ness
-rib
ratio
to m
ater
ial, i
ncre
asin
g
hold
ing
pres
sure
and
hol
ding
pre
ssur
e tim
e, a
nd
mak
ing
nozz
le a
pert
ure
and
spru
e cr
oss-
sect
ion
larg
er. R
educ
e m
elt a
nd m
old
tem
pera
ture
s (m
ay
resu
lt in
form
atio
n of
voi
ds). C
heck
mel
t cus
hion
. If
nece
ssar
y, la
min
ate
sink
mar
ks
Des
crip
tion:
Del
amin
atio
n. S
urfa
ce la
yer d
etac
hes
or fl
akes
off.
Ca
n oc
cur o
ver e
xten
sive
are
as o
f mol
ding
or j
ust n
ear s
prue
s
Des
crip
tion:
Loc
alize
d, p
rono
unce
d de
pres
sion
in s
urfa
ce, m
ostly
opp
osite
rib
s, a
t thi
ck-w
alle
d lo
catio
ns, c
ores
, wel
d lin
es, t
hroa
ts, h
ot ru
nner
noz
zles
or
end
of fl
ow p
aths
Del
amin
atio
n
Sin
k m
arks
, loc
aliz
ed
28 29
Caus
es:
Rem
edie
s:
Inad
equa
te m
old
vent
ing
Impr
ove
mol
d ve
ntin
g, e
spec
ially
at e
nd o
f flow
pa
th
Inad
equa
te p
last
ic fl
ow p
rope
rtie
s. In
suffi
cien
t in
ject
ion
spee
d. W
all t
hick
ness
inad
equa
te / fl
ow
path
s to
o lo
ng
Impr
ove
flow
prop
ertie
s by i
ncre
asin
g m
elt a
nd
mol
d te
mpe
ratu
res.
Incr
ease
inje
ctio
n sp
eed.
In
crea
se w
all t
hick
ness
or,
if ne
cess
ary,
mov
e
gate
s to
sho
rten
flow
pat
hs
N.B
.:Fa
ult m
ostly
occ
urs
with
hig
h-vi
scos
ity o
r qui
ck-
setti
ng th
erm
opla
stic
s. F
or th
erm
opla
stic
s w
ith a
lo
w p
ro - c
essi
ng te
mpe
ratu
re (e
. g. P
S), w
eld
line
can
be la
min
ated
usi
ng th
e Pr
omol
d® pro
cess
.
Caus
es:
Rem
edie
s:
Gla
ss fi
bers
sta
ndin
g up
at e
nd o
f flow
pat
h or
at
wel
d lin
es
Chan
ge fl
ow fr
ont o
r m
ove
wel
d lin
e to
no
n-cr
itica
l are
a
Hold
ing
pres
sure
not
suffi
cien
tly e
ffect
ive
Switc
h fro
m in
ject
ion
to
hold
ing
pres
sure
late
r an
d in
crea
se b
oth
hold
ing
pr
essu
re a
nd h
oldi
ng
pres
sure
tim
e
Des
crip
tion:
Ext
ensi
ve c
ontra
ctio
n of
mol
ding
aw
ay fr
om m
old
surfa
ce
exce
pt a
t edg
es
Des
crip
tion:
Pro
noun
ced
wel
d lin
e, n
otch
alo
ng w
eld
line
whi
ch
can
be s
een
or fe
lt
Smin
Smax
Dog
’s b
one
effec
t, ex
tens
ive
sink
mar
ks
Not
ches
alo
ng w
eld
line
30 31
Caus
es:
Rem
edie
s:
Mel
t flow
in m
old
puls
ates
due
to e
xces
sive
co
olin
g of
mel
t fro
nt.
Try
to o
btai
n qu
ick,
uni
form
mel
t flow
Inje
ctio
n sp
eed
too
low
Incr
ease
inje
ctio
n sp
eed
Mel
t tem
pera
ture
too
low
Incr
ease
mel
t tem
pera
ture
Mol
d te
mpe
ratu
re to
o lo
wIn
crea
se m
old
tem
pera
ture
Wal
l thi
ckne
ss to
o lo
wIn
crea
se w
all t
hick
ness
Caus
es:
Rem
edie
s:
Ther
mal
dam
age
to m
ater
ial. E
xces
sive
resi
denc
e tim
e in
cyl
inde
r or h
ot ru
nner
. Mel
t tem
pera
ture
to
o hi
gh
Redu
ce m
elt’s
exp
osur
e to
hea
t. Re
duce
re
side
nce
time
in c
ylin
der o
r hot
runn
er.
Low
er m
elt t
empe
ratu
re
Des
crip
tion:
Rec
ord
groo
ves,
stic
k-sl
ip e
ffect
. In
spr
ue a
rea:
Fin
e, c
once
ntric
gro
oves
aro
und
gate
. In
thin
-wal
led
area
s: G
roov
es p
aral
lel t
o flo
w fr
ont
Des
crip
tion:
Pro
noun
ced
odor
s, e
ither
typi
cal o
r aty
pica
l of m
ater
ial
1.6
Pro
cess
ing
defe
cts
Gro
oves
Unu
sual
odo
r
32 33
Caus
es:
Rem
edie
s:
Non-
retu
rn v
alve
def
ectiv
e or
wor
nCh
eck
non-
retu
rn v
alve
and
repl
ace
with
a n
ew
one
if ne
cess
ary
Hydr
aulic
s fa
ulty
Chec
k hy
drau
lics
are
wor
king
pro
perly
Unev
en m
eter
ing
Chec
k cy
linde
r bar
rel f
or w
ear a
nd if
nec
essa
ry
fit b
ush
or u
se n
ew p
last
icat
ing
unit
Caus
es:
Rem
edie
s:
Met
erin
g tim
e to
o lo
ng
Cut m
eter
ing
time.
Incr
ease
scr
ew s
peed
to m
axi-
mum
per
iphe
ral v
eloc
ity o
f 0.2
5 m
/ s.
Use
larg
er
plas
ticat
ing
unit.
Che
ck p
last
icat
ing
unit
for w
ear.
Use
mor
e effi
cien
t scr
ew
Cool
ing
time
too
long
Cut c
oolin
g tim
e. R
educ
e m
old
tem
pera
ture
with
in
perm
itted
limits
. Impr
ove
cool
ing,
targ
etin
g cr
itica
l ar
eas
Hand
ling
time
too
long
Impr
ove
hand
ling
syst
em
Des
crip
tion:
Mel
t cus
hion
var
ies
grea
tly, s
omet
imes
app
roac
hing
zero
Inje
ctio
n
Met
erin
g
Tim
e (s
)
Hol
ding
pre
ssur
e
Screw stroke (mm)
Mel
t cus
hion
of
10 c
ycle
s
Des
crip
tion:
Act
ual c
ycle
tim
e ex
ceed
s sc
hedu
led
cycl
e tim
e
Mel
t cus
hion
fluc
tuat
es
Cyc
le to
o lo
ng
34 35
Caus
es:
Rem
edie
s:
Unsu
itabl
e de
sign
of p
art.
Unsu
itabl
e gl
ass
fiber
or
ient
atio
n. U
nsui
tabl
e w
all t
hick
ness
dis
tribu
tion
Opt
imize
des
ign
of m
oldi
ng. Im
prov
e gl
ass
fiber
or
ient
atio
n by
opt
imizi
ng g
ate.
Opt
imize
wal
l thi
ck-
ness
dis
tribu
tion
Hold
ing
pres
sure
not
suffi
cien
tly e
ffect
ive.
No
n-re
turn
val
ve w
orn
Switc
h fro
m in
ject
ion
pres
sure
to h
oldi
ng p
ress
ure
late
r and
incr
ease
hol
ding
pre
ssur
e. C
heck
non
-re
turn
val
ve a
nd re
plac
e if
nece
ssar
y
N.B
.:Po
ssib
le c
ause
s of
def
ect,
asso
ciat
ed re
med
ies
and
thei
r int
erde
pend
enci
es a
re to
o co
mpl
ex to
go
into
her
e.
Caus
es:
Rem
edie
s:
Inje
ctio
n sp
eed
inad
equa
teIn
crea
se in
ject
ion
spee
d
Mol
d te
mpe
ratu
re to
o lo
w
Incr
ease
mol
d te
mpe
ratu
re. E
quip
mol
d w
ith
ther
mal
insu
latio
n. U
se m
ore
effici
ent t
empe
ratu
re-
cont
rol u
nit
N.B
.:O
nly
affec
ts g
lass
-fibe
r-re
info
rced
ther
mop
last
ics.
Ve
ry e
vide
nt o
n am
orph
ous
ther
mop
last
ics,
less
so
on
sem
i-cry
stal
line
ther
mop
last
ics
Des
crip
tion:
Mol
ding
s no
t as
show
n in
dra
win
g, d
isto
rted
or
do n
ot fi
t tog
ethe
r acc
urat
ely
1.7
War
page
def
ects
Des
crip
tion:
Rou
gh, m
att p
art s
urfa
ce
1.8
Glo
ss d
efec
ts
War
page
, gen
eral
Fro
stin
g
36 37
Caus
es:
Rem
edie
s:
Inad
equa
te in
ject
ion
spee
dIn
crea
se in
ject
ion
spee
d
Mol
d su
rface
wor
n or
cor
rode
dRe
wor
k m
old
surfa
ce
Fluc
tuat
ing
mol
d te
mpe
ratu
res.
Fau
lt in
hea
ting
/ co
olin
g ci
rcui
t, e.
g. le
ak, h
eatin
g / c
oolin
g ch
anne
l bl
ocke
d, te
mpe
ratu
re c
ontro
l uni
t not
wor
king
Serv
ice
tem
pera
ture
con
trol s
yste
m a
nd re
pair
leak
if n
eces
sary
. Impr
ove
tem
pera
ture
con
trol w
ith
addi
tiona
l hea
ting
/ coo
ling
chan
nels
, by
incr
easi
ng
heat
ing
/ coo
ling
med
ium
thro
ughp
ut o
r by
chan
g-in
g th
is m
ediu
m (w
ater
inst
ead
of o
il)
Caus
es:
Rem
edie
s:
Mol
d po
lishi
ng in
adeq
uate
or w
orn
Impr
ove
mol
d po
lishi
ng
Inad
equa
te in
ject
ion
spee
d, p
ossi
bly
due
to
poor
ven
ting
Incr
ease
inje
ctio
n sp
eed,
if n
eces
sary
by
im
prov
ing
vent
ing
Fluc
tuat
ing
mol
d te
mpe
ratu
re d
ue to
insu
ffici
ent
cool
ing
Chec
k m
old
for u
nifo
rm te
mpe
ratu
re
Inad
equa
te m
ater
ial d
ryin
gCh
eck
dryi
ng p
roce
ss
Hold
ing
pres
sure
not
suffi
cien
tly e
ffect
ive
Incr
ease
hol
ding
pre
ssur
e an
d ho
ldin
g pr
essu
re
time.
If n
eces
sary
, wid
en g
ates
Des
crip
tion:
Diff
eren
t glo
ss le
vels
, eith
er o
ver e
ntire
mol
ded
pa
rt o
r at v
ario
us lo
catio
ns
Des
crip
tion:
Mol
ding
fails
to a
chie
ve re
quire
d gl
oss
leve
l eith
er o
ver
entir
e su
rface
or i
n a
spec
ific
area
Glo
ss le
vel n
ot a
chie
ved
on p
olis
hed
surf
ace
Glo
ss d
iffer
entia
l on
mol
ded
part
sur
face
38 39
Caus
es:
Rem
edie
s:
Prem
atur
e ej
ectio
nEx
tend
cyc
le ti
me
Inad
equa
te h
oldi
ng p
ress
ure
and
hold
ing
pr
essu
re ti
me
Incr
ease
hol
ding
pre
ssur
e, e
xten
d ho
ldin
g pr
essu
re
time,
che
ck m
elt c
ushi
on. C
heck
noz
zle a
pert
ure,
sp
rue
cros
s-se
ctio
n an
d ga
te c
ross
-sec
tion
and
wid
en if
nec
essa
ry
Prem
atur
e sw
itch
to h
oldi
ng p
ress
ure
Switc
h to
hol
ding
pre
ssur
e la
ter
Loca
lized
exc
essi
ve m
old
tem
pera
ture
Low
er m
old
tem
pera
ture
on
a lo
caliz
ed b
asis
us
ing
addi
tiona
l coo
ling
chan
nels
or s
epar
ate
te
mpe
ratu
re c
ontro
l
N.B
.:Se
e al
so “M
att s
urfa
ce d
efec
ts”
Caus
es:
Rem
edie
s:
Spee
d di
ffere
nces
bet
wee
n flo
w fr
onts
(if s
ever
al
inje
ctio
n po
ints
)Ev
en o
ut s
peed
diff
eren
ces
by b
alan
cing
gat
ing
syst
em (if
sev
eral
inje
ctio
n po
ints
)
Tear
ing
of a
lread
y so
lidifi
ed o
uter
ski
n at
sha
rp
bend
s or
sud
den
chan
ges
in w
all t
hick
ness
Roun
d off
or p
olis
h ch
ange
s in
wal
l thi
ckne
ss
and
trans
ition
s in
gat
e / m
old
or a
djus
t flow
fron
t sp
eed
N.B
.:Se
e al
so “F
laki
ng”
Des
crip
tion:
Mat
t hal
o, d
ull s
pot.
Unifo
rm, w
ell-d
efine
d ve
lvet
y ar
ea
Des
crip
tion:
Shi
ny h
ollo
ws,
ofte
n ne
ar s
prue
s, a
t cor
es o
r clo
se
to h
ot ru
nner
ele
men
ts, o
ften
assu
med
to b
e bo
ndin
g sp
ots
Loc
aliz
ed, s
hiny
, fing
er-li
ke h
ollo
ws
Dul
l spo
ts
40 41
Caus
es:
Rem
edie
s:
Inje
ctio
n sp
eed
and
mol
d te
mpe
ratu
re to
o lo
wIn
crea
se in
ject
ion
spee
d an
d m
old
tem
pera
ture
Hold
ing
pres
sure
not
suffi
cien
tly e
ffect
ive
Switc
h to
hol
ding
pre
ssur
e la
ter a
nd in
crea
se
hold
ing
pres
sure
Surfa
ce te
xtur
e in
adeq
uate
or w
orn
Rew
ork
mol
d su
rface
Caus
es:
Rem
edie
s:
Prem
atur
e ej
ectio
nEx
tend
coo
ling
time
Mol
d te
mpe
ratu
re to
o hi
gh a
t hot
runn
erIm
prov
e th
erm
al s
epar
atio
n of
hot
runn
er, r
educ
e m
old
tem
pera
ture
Core
tem
pera
ture
too
high
Ensu
re a
dequ
ate
cool
ing
of c
ore
Des
crip
tion:
Rou
gh, c
rack
ed s
urfa
ce, c
reat
ing
a m
att e
ffect
cl
ose
to h
ot ru
nner
ele
men
ts o
r at h
ot c
ores
Des
crip
tion:
Req
uire
d m
att a
ppea
ranc
e no
t ach
ieve
d on
sur
face
of
mol
ding
Mat
t sur
face
def
ects
at h
ot ru
nner
ele
men
ts
Mat
t app
eara
nce
not a
chie
ved
on te
xtur
ed su
rfac
e
42 43
Caus
es:
Rem
edie
s:
Inad
equa
te d
rafts
Mak
e dr
afts
larg
er
Mol
d su
rface
dam
aged
Rew
ork
mol
d su
rface
Cavi
ty p
ress
ure
too
high
Redu
ce c
avity
pre
ssur
e. S
witc
h fro
m in
ject
ion
to
hold
ing
pres
sure
ear
lier.
Redu
ce h
oldi
ng p
ress
ure.
O
ptim
ize in
ject
ion
spee
d. In
crea
se m
elt
tem
pera
ture
with
in p
erm
itted
limits
Inad
equa
te m
old
rigid
ity
Incr
ease
mol
d rig
idity
N.B
.:Sc
orin
g ca
n of
ten
only
be
iden
tified
usi
ng
optic
al a
ids.
Caus
es:
Rem
edie
s:
Mat
eria
l too
moi
stCh
eck
drye
r / d
ryin
g pr
oces
s
Mel
t tem
pera
ture
too
high
, res
iden
ce ti
me
in
cylin
der a
nd h
ot ru
nner
too
long
Chec
k m
elt t
empe
ratu
re, m
elt r
esid
ence
tim
e
and
scre
w s
peed
and
redu
ce if
nec
essa
ry
Des
crip
tion:
Whi
tish,
roug
h, fl
aky
patc
hes
or w
hitis
h ro
und
or
oval
pat
ches
rese
mbl
ing
mild
ew
Des
crip
tion:
Cra
cked
, rou
gh s
urfa
ce w
ith s
corin
g in
dire
ctio
n of
re
mov
al (d
emol
ding
), mos
tly a
t sam
e lo
catio
n
Dam
age
to g
rain
on
mol
ded
part
Whi
te p
atch
es
44 45
Caus
es:
Rem
edie
s:
Insu
ffici
ent m
old
vent
ing
Impr
ove
mol
d ve
ntin
g
Inad
equa
te p
last
ic fl
ow p
rope
rtie
s. In
ject
ion
sp
eed
too
low.
Wal
l thi
ckne
ss in
adeq
uate
/ flo
w
path
s to
o lo
ng
Impr
ove
flow
pro
pert
ies.
Incr
ease
inje
ctio
n sp
eed.
In
crea
se m
elt a
nd m
old
tem
pera
ture
s. In
crea
se
wal
l thi
ckne
ss o
r rel
ocat
e ga
tes
if ne
cess
ary
to
shor
ten
flow
pat
hs
Caus
es:
Rem
edie
s:
Inco
rrect
mat
eria
l sel
ectio
n, e
.g. a
mor
phou
s
ther
mop
last
ics
Use
a su
itabl
e se
mi-c
ryst
allin
e th
erm
opla
stic
Wel
d lin
e in
uns
uita
ble
posi
tion
in in
tegr
al h
inge
Chan
ge w
eld
line
and
com
ply
with
des
ign
gu
idel
ines
for i
nteg
ral h
inge
s
Des
crip
tion:
Inte
gral
hin
ges
tear
or b
reak
und
er s
tress
Des
crip
tion:
Par
t fai
lure
nea
r wel
d lin
e
1.9
Def
ects
in m
echa
nica
l pro
pert
ies
Wel
d lin
e st
reng
th in
suffi
cien
t
Def
ectiv
e in
tegr
al h
inge
s
46 47
Caus
es:
Rem
edie
s:
Exce
ssiv
e m
echa
nica
l stre
ss
Chec
k di
men
sion
ing
mee
ts m
echa
nica
l req
uire
-m
ents
. Che
ck m
olde
d pa
rts’
inte
rnal
stre
ss le
vels
(if
nec
essa
ry, in
crea
se m
old
and
mel
t tem
pera
-tu
res,
redu
ce c
avity
pre
ssur
e). C
heck
pla
stic
s’
resi
stan
ce to
med
ia
Mat
eria
l deg
rada
tion
due
to in
corre
ct d
ryin
g or
ov
erex
posu
re to
hea
tCh
eck
mel
t tem
pera
ture
, res
iden
ce ti
me
and
dr
ying
pro
cess
Wel
d lin
e in
uns
uita
ble
posi
tion
Loca
te w
eld
line
outs
ide
area
whe
re m
ain
stre
ss
occu
rs
Poor
dem
oldi
ng b
ehav
ior a
t dom
es a
nd s
crew
co
nnec
tions
Avoi
d da
mag
ing
part
dur
ing
rem
oval
(dem
oldi
ng),
impr
ove
rem
oval
beh
avio
r by
polis
hing
mol
d
Caus
es:
Rem
edie
s:
Disp
lace
men
t of a
lread
y co
oled
mat
eria
lIn
ject
in s
tage
s –
slow
to fa
st. R
educ
e m
old
te
mpe
ratu
re. P
rovi
de g
ates
with
radi
i and
pol
ish
Des
crip
tion:
Col
d di
spla
cem
ent.
Surfa
ce lo
oks
flaky
with
al
tern
atin
g sh
iny
and
mat
t are
as, m
ostly
nea
r spr
ues
1.10
Sur
face
def
ects
Des
crip
tion:
Mol
ding
not
up
to m
echa
nica
l req
uire
men
ts
Mec
hani
cal p
robl
ems
with
par
t
Fla
king
48 49
Caus
es:
Rem
edie
s:
Plas
ticat
ing
unit’
s m
eter
ing
stro
ke to
o hi
gh
Use
larg
er p
last
icat
ing
unit
to re
duce
met
erin
g st
roke
(‹3D
). If p
last
icat
ing
unit
cann
ot b
e ch
ange
d,
incr
ease
feed
sec
tion
tem
pera
ture
, red
uce
scre
w
spee
d, in
crea
se c
ycle
tim
e an
d if
nece
ssar
y in
-cr
ease
size
of m
elt c
ushi
on, if
pos
sibl
e by
1-2
D,
as a
n ad
ditio
nal r
emed
ial m
easu
re
Air i
ntak
e du
ring
met
erin
g
Opt
imize
pla
stic
atin
g co
nditi
ons.
Incr
ease
bac
k
pres
sure
with
in p
erm
itted
limits
. Sho
rten
scr
ew
retra
ctio
n. L
et m
achi
ne n
ozzle
con
tact
hot
runn
er
mol
d
N.B
.:Fa
ult s
omet
imes
occ
urs
in a
ssoc
iatio
n w
ith
blis
terin
g.
Caus
es:
Rem
edie
s:
Unsu
itabl
e ga
te o
r thr
oat w
ith re
sult
that
no
fro
ntal
flow
is p
rodu
ced.
Gat
e po
sitio
n ha
s no
de
flect
or s
urfa
ce.
Gat
e cr
oss-
sect
ion
or th
roat
too
smal
l
Chan
ge g
ate.
Sel
ect g
ate
posi
tion
with
defl
ecto
r su
rface
s. M
ake
gate
cro
ss-s
ectio
n la
rger
. Im
prov
e de
sign
of c
hang
es in
dia
met
er
Inje
ctio
n sp
eed
too
high
Giv
e pr
efer
ence
to in
ject
ion
in s
tage
s –
slow
to
fast
.
Des
crip
tion:
Jet
ting.
Mel
t whi
ch h
as e
nter
ed c
avity
firs
t is
visi
ble
on
part
sur
face
(mos
tly S
-sha
ped)
. Fau
lt oc
curs
nea
r spr
ues
or a
t thr
oats
Des
crip
tion:
Ext
ensi
ve e
long
ated
pen
icilla
te s
treak
s
Jet
ting
Ext
ensi
ve s
ilver
str
eaks
50 51
Caus
es:
Rem
edie
s:
Sprin
g-lo
aded
gat
e va
lves
Impr
ove
gate
val
ve s
uppo
rt /
mol
d rig
idity
Gla
ss fi
bers
sta
ndin
g up
at w
eld
lines
Chan
ge p
ositi
on o
f wel
d lin
e, if
nec
essa
ry a
lso
us
ing
spru
e po
sitio
n an
d nu
mbe
r of g
ates
Sudd
en c
hang
es in
rigi
dity
at r
ibs
or s
udde
n ch
ange
s in
wal
l thi
ckne
ssAv
oid
sudd
en c
hang
es in
wal
l thi
ckne
ss a
nd
prov
ide
grad
ual t
rans
ition
s
Caus
es:
Rem
edie
s:
Air i
ntak
e du
ring
met
erin
g
Chec
k gr
anul
e co
nvey
ing
syst
em
for a
ir in
take
. Incr
ease
bac
k
pres
sure
with
in p
erm
itted
limits
. Sh
orte
n sc
rew
retra
ctio
n
Capa
city
util
izatio
n of
pla
stic
atin
g un
it to
o hi
ghIf
scre
w s
troke
exc
eeds
3D,
use
pla
stic
atin
g un
it on
e si
ze la
rger
Des
crip
tion:
Dep
endi
ng o
n an
gle
of lig
ht, c
lear
ly d
isce
rnib
le lin
e
or s
him
mer
ing
area
on
part
, ofte
n at
wel
d lin
es, r
ibs,
sud
den
chan
ges
in
wal
l thi
ckne
ss o
r slid
e va
lves
Des
crip
tion:
Hol
low
bub
bles
fille
d w
ith a
ir in
wal
l
Buc
klin
g lin
e
Lar
ge b
ubbl
es
52 53
Caus
es:
Rem
edie
s:
Resi
dual
moi
stur
e co
nten
t of p
elle
ts to
o hi
ghCh
eck
dryi
ng p
roce
ss (d
ryin
g te
mpe
ratu
re a
nd
time
and
hour
ly th
roug
hput
). Che
ck d
ryer
for s
oile
d fil
ters
. Che
ck d
rive
mot
or’s
dire
ctio
n of
rota
tion
Caus
es:
Rem
edie
s:
Mol
d’s
surfa
ce te
xtur
e da
mag
edCh
eck
mol
d’s
surfa
ce te
xtur
e an
d re
wor
k if
ne
cess
ary,
polis
h in
dire
ctio
n of
rem
oval
Sprin
g-lo
aded
gat
e va
lves
Opt
imize
slid
e va
lves
Exce
ssiv
e ca
vity
pre
ssur
e
Redu
ce c
avity
pre
ssur
e. S
witc
h fro
m in
ject
ion
to
hol
ding
pre
ssur
e ea
rlier
. Red
uce
hold
ing
pr
essu
re. O
ptim
ize in
ject
ion
spee
d. In
crea
se m
elt
tem
pera
ture
with
in p
erm
itted
limits
Inad
equa
te m
old
rigid
ity
Rein
forc
e m
old
N.B
.:Se
e al
so “N
oise
s as
mol
d op
ens”
Des
crip
tion:
Sco
ring,
scr
atch
es. S
corin
g or
scr
atch
es o
n pa
rt
surfa
ce ru
nnin
g in
dire
ctio
n of
rem
oval
(dem
oldi
ng), a
lso
visi
ble
as
mat
t stri
pes
on h
igh-
glos
s su
rface
Des
crip
tion:
Moi
stur
e st
reak
s. U
-sha
ped,
elo
ngat
ed, t
ufte
d st
reak
s,
open
tow
ards
flow
dire
ctio
n; in
a le
ss p
rono
unce
d ve
rsio
n in
the
form
of
sm
all li
nes
Lin
ear s
urfa
ce d
amag
e
Str
eaks
ope
n to
war
ds fl
ow d
irect
ion
54 55
Caus
es:
Rem
edie
s:
Ove
rhea
ting
of m
elt,
mel
t tem
pera
ture
too
high
Redu
ce th
erm
al s
tress
on
mel
t, lo
wer
mel
t te
mpe
ratu
re
Ove
rhea
ting
of m
elt,
mel
t res
iden
ce ti
me
too
long
Redu
ce th
erm
al s
tress
on
mel
t, se
lect
sm
alle
r sc
rew
dia
met
er
Ove
rhea
ting
of m
elt,
scre
w s
peed
too
high
Redu
ce th
erm
al s
tress
on
mel
t, lo
wer
scr
ew s
peed
Ove
rhea
ting
of m
elt,
nozz
le a
nd ru
nner
s to
o
narro
wRe
duce
ther
mal
stre
ss o
n m
elt,
wid
en n
ozzle
an
d ru
nner
s
Ove
rhea
ting
of m
elt,
prod
uctio
n st
oppa
ge w
ithou
t re
duct
ion
in te
mpe
ratu
re
Redu
ce th
erm
al s
tress
on
mel
t, co
mpl
y w
ith
inst
ruct
ions
for p
rodu
ctio
n st
oppa
ge
N.B
.:Fa
ult o
ften
sim
ilar t
o m
oist
ure
stre
aks.
Caus
es:
Rem
edie
s:
Air r
olle
d ov
er a
nd tr
appe
d in
inje
ctio
n m
old,
e.g
. fro
m e
ngra
ving
s, g
roov
es o
r dep
ress
ions
Redu
ce in
ject
ion
spee
d in
crit
ical
are
a. Im
prov
e m
old
vent
ing
clos
e to
flow
lines
and
nea
r dep
res-
sion
s, fl
ange
s or
eng
ravi
ngs.
Eva
cuat
e m
old
Des
crip
tion:
Silv
er s
treak
s. E
long
ated
silv
ery
stre
aks
Des
crip
tion:
Air-
fille
d ho
ok. L
ines
in s
hape
of h
ook
/ tea
r dro
p ca
used
by
trap
ped
air
Str
eaks
due
to o
verh
eatin
g, n
eedl
e-lik
e st
reak
s
Tea
r dro
ps
56 57
Caus
es:
Rem
edie
s:
Mat
eria
l too
moi
stCh
eck
dryi
ng p
roce
ss
Unsu
itabl
e ve
nted
scr
ew
Sele
ct a
ppro
pria
te v
ente
d sc
rew
or r
epla
ce
vent
ed s
crew
with
nor
mal
one
and
pre
-dry
m
ater
ial
N.B
.:Fa
ult o
ften
coin
cide
s w
ith s
ilver
stre
aks.
Caus
es:
Rem
edie
s:
Ejec
tor c
law
on
cold
runn
er ro
d m
issi
ng o
r too
sm
all t
o ab
sorb
col
d sl
ugPr
ovid
e or
opt
imize
eje
ctor
cla
w s
o th
at c
old
sl
ug is
abs
orbe
d
Mel
t lea
king
from
mac
hine
noz
zle o
r hot
runn
erIn
crea
se s
crew
retra
ctio
n, o
ptim
ize th
erm
al
sepa
ratio
n in
hot
runn
er
Nozz
le a
pert
ure
and
heat
ing
inad
equa
teM
ake
nozz
le a
pert
ure
larg
er, in
stal
l ban
d he
ater
w
ith h
ighe
r cap
acity
, che
ck th
erm
ocou
ple
and
cont
rolle
r
Des
crip
tion:
Col
d-flo
w m
ark.
Wel
l-defi
ned,
irre
gula
r mat
te a
rea.
Co
ld m
elt p
artic
les
entra
pped
in s
urfa
ce o
f mol
ding
Des
crip
tion:
Ent
rapp
ed a
ir si
mila
r to
void
s bu
t gre
ater
in
num
ber a
nd w
ith m
uch
smal
ler d
iam
eter
s
Col
d sl
ug
Sm
all b
ubbl
es
58 59
Caus
es:
Rem
edie
s:
Mat
eria
l deg
rada
tion
Redu
ce m
elt t
empe
ratu
re a
nd re
side
nce
time
Pigm
ent h
as d
etrim
enta
l effe
ct (u
se o
f inc
om-
patib
le p
igm
ents
for i
n-pl
ant c
olor
ing,
ofte
n
wro
ng ty
pe o
f car
bon
blac
k)
Use
com
patib
le p
igm
ents
or d
iffer
ent t
ype
of
carb
on b
lack
Prop
ortio
n of
car
bon
blac
k to
o hi
ghRe
duce
pro
port
ion
of c
arbo
n bl
ack
Caus
es:
Rem
edie
s:
Plas
ticat
ing
unit
wor
nCh
eck
plas
ticat
ing
unit
for s
crew
, cyl
inde
r or
non-
retu
rn v
alve
wea
r
Fore
ign
bodi
es d
ue to
feed
pip
e, c
onta
iner
and
fe
ed h
oppe
r abr
asio
n
Chec
k pi
pes,
con
tain
ers
and
feed
hop
pers
for
abra
sion
. Mak
e su
ch p
ipes
, con
tain
ers
and
ho
pper
s fro
m s
tain
less
ste
el –
alu
min
um a
nd
tinpl
ate
are
unsu
itabl
e. A
void
ben
ds a
s fa
r as
po
ssib
le, o
ther
wis
e de
sign
with
larg
e ra
dii
Gra
nula
tor f
or p
rodu
cing
recl
aim
wor
nCh
eck
gran
ulat
ors
regu
larly
for a
bras
ion
/ dam
age
and
repa
ir w
hen
nece
ssar
y
Des
crip
tion:
Pin
hole
s, p
impl
es. D
epre
ssio
ns th
e si
ze o
f pin
pric
ks
Des
crip
tion:
Met
al s
peck
s. G
ray
fore
ign
part
icle
s w
hich
may
app
ear
shin
y, de
pend
ing
on a
ngle
of l
ight
Cra
ters
Gra
y do
ts
60 61
Caus
es:
Rem
edie
s:
Stre
ss le
vels
too
high
in m
olde
d pa
rt
Opt
imize
pro
cess
ing
para
met
ers
with
rega
rd
to s
tress
leve
ls. In
crea
se m
old
and
mel
t tem
pera
-tu
res.
Des
ign
mol
ding
to re
duce
long
-ter
m o
uter
fib
er s
train
Cont
act w
ith in
appr
opria
te m
edia
Chec
k m
edia
com
patib
ility.
Chec
k re
leas
e an
d
anti-
corro
sion
age
nts
to s
ee if
they
cau
se s
tress
cr
acki
ng. C
heck
mol
ded
part
s fo
r che
mic
al
resi
stan
ce to
cle
anin
g / d
egre
asin
g ag
ents
. Ch
eck
resi
stan
ce to
med
ia u
sed
and
redu
ce
load
if n
eces
sary
Caus
es:
Rem
edie
s:
No c
ompe
nsat
ion
for v
olum
e co
ntra
ctio
n du
ring
cool
ing
phas
e. H
oldi
ng p
ress
ure
not s
uffici
ently
eff
ectiv
e
Incr
ease
hol
ding
pre
ssur
e, e
xten
d ho
ldin
g
pres
sure
tim
e, c
heck
mel
t cus
hion
. Che
ck n
ozzle
ap
ertu
re, s
prue
cro
ss-s
ectio
n an
d ga
te c
ross
- se
ctio
n an
d m
ake
larg
er if
nec
essa
ry
No c
ompe
nsat
ion
for v
olum
e co
ntra
ctio
n du
ring
cool
ing
phas
e. U
nsui
tabl
e in
ject
ion
posi
tion
or
part
des
ign
Inje
ct in
thic
k-w
alle
d ar
ea. R
evis
e w
all t
hick
ness
es
to a
void
exc
essi
ve c
hang
es in
thic
knes
s
N.B
.:Co
mpl
y w
ith d
esig
n gu
idel
ines
for i
njec
tion
m
olde
d pa
rts
Des
crip
tion:
Fin
e, m
icro
scop
ic c
rack
s in
mol
ded
part
, ofte
n ju
st
on s
urfa
ce o
f out
er fi
bers
und
er te
nsile
stre
ss
Des
crip
tion:
Vac
uole
, bub
ble.
Rou
nd o
r elo
ngat
ed b
ubbl
es (h
ollo
w
vacu
ums)
, gen
eral
ly o
nly
disc
erni
ble
on tr
ansp
aren
t or t
rans
luce
nt p
arts
Mic
rosc
opic
cra
cks
Voi
ds
Not
es
62 63
64 65
Not
es