Installation and Troubleshooting Guide - CDI Electronics · Installation and Troubleshooting Guide
Troubleshooting Guide PET
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South Asian Petrochem Limited
TROUBLESHOOTING GUIDE
Injection MoldingProblem Possible causes Possible Solutions
1. SHORT SHOTS
Incomplete formationof preform.
Injection Pressure low
Barrel temperature low
Mould manifold temp. low
Mould cavity temp. low
Increase injection pressure
Increase barrel temperature
Increase mould manifold temperature
Increase mould cavity temperature.
Increase injection speed
Increase back pressure
Clean vent on split, core and cavity
Ceck tat no foreign object is in gate area. Ceck tat te gate pin is moving all te way
back !In valve gate ot runner"
2. SINK MARKS
Depression in thepreform surface / body
#olding pressure low
#olding time low
#ig mold temperature
Inade$uate coolant supply
Cooling time low
Blocked venting
Increase olding pressure
Increase olding time
%ecrease mould temperature
Ceck cooling water flow & temperature.
Increase cooling time
Clean vents on split, core and cavity
3. WATER MARKSWavy water marks,due to absorption ofwater by hot melt.
'eaking oses 'eaking mould
Insufficient deumidification
Mold enclosure inade$uate
Ceck oses on mould for damage
Ceck mould for leaks
Ceck tat deumidifier is working properly
Ceck tat te macine enclosures as nomajor gaps
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4. FLASH
Fins along the partingsline created by outflowing polymer.
Injection pressure ig
#ig injection speed
(nwanted material in cores
(nwanted material in splits
(nwanted material in cavity
#ig mold temperature
#ig barrel temperature
Clamping pressure low
%ecrease Injection pressure
%ecrease injection speed
Clean cores
Clean splits
Clean cavity
%ecrease mould temperature
%ecrease barrel temperature
Increase clamp pressure
5. BLACK SPECS
/CONTAMINATION
Contaminated resin
#ig residence time prior torestart of te macine
%egradation of resin
Ceck for resin cleanliness
Clean te resin opper Purge te barrel torougly on restart
)educe melt temperature
)educe back pressure
6. FLOW LINES POOR.
Wavy flow lines,observed in thepolarized light.
Injection pressure low
Mould temperature low
Barrel temperature low
Injection speed low
%rier inefficient Back pressure low
Increase injection pressure
Increase mould temperature
Increase barrel temperature
Increase injection speed
Ceck resin drier
Increase back pressure
7. HEAT SPLAY
White / orange shadedflow marks, visible tonaked eyes.
Manifold and mold eaterMalfunction.
Barrel temperature ig
*oreign matter in te gate
Ceck temperature of mould cavity eatersand Manifold
Ceck barrel temperature
Ceck tat no foreign material is in gate area
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8. PET INCLUSIONS
n!melted polymer "fine dusty appearancein preform.
'ow barrel temperature
'ow mould temperature Back pressure low
Mi+ing ead damage
Ceck valve damage
Ceck barrel temperature
Ceck mould temperature
Increase back pressure Ceck tat te mi+ing ead of te screw or te
screw is not broken.
Inspect te ceck valve on te screw !not#usky Macine"
9. CONCENTRICITY Injection speed ig
Injection core bent
%ecrease injection speed
Ceck tat te injection core is not bent andstraigten it.
1. CRYSTALLINE !ATE
White crystallineappearance of areaaround gate.
Cavity eater malfunction
Cavity temperature low
Manifold temperature low
%rier malfunction
#old pressure ig
*oreign material in gate
Cooling insufficient
Core cooling inade$uate
Ceck tat te cavity eater is working
Increase te cavity temperature
Increase te manifold temperature
Ceck tat te drier is working
%ecrease injection old pressure
Ceck tat no foreign object obstructs tecavity gate Increase cooling time
Ceck water to injection core and cavity
Ceck cooling tube in gate is straigt and flow
is ok.
11. LON! !ATE
#$tended %ate length Cavity eater malfunction
Cavity eater low
ate valve malfunction
Sut-off nole malfunction
Ceck cavity eater
Increase cavity temperature
Ceck tat te gate valve is working
Ceck tat te barrel sut-off nole is working
Increase decompression time
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Sort decompression time
12. AIR BUBBLES#ntrapped air or gas orvacuum bubble.
Barrel temperature low Inefficient drying
'ow back pressure
Barrel temperature ig.
Mi+ing ead damage
Ceck barrel temperature Ceck drier temperature
Increase back pressure
'ower temperature at last e+truder one
Ceck e+truder mi+ing ead
13. STRESS PATTERNWaviness in &olarized light.
#ig injection pressure
#ig sot sie
'ong old time
%ecrease injection pressure
)educe sot sie
%ecrease injection old time
14. STRIN!IN!
'ong fine stringe$tending from thegate.
#ig cavity temperature
'ow cooling time
'ow old time
Inade$uate coolant to cavity
ate valve malfunction
)educe cavity temperature
Increase cooling time
Increase injection old time
Ceck water flow to cavities
Ceck tat gate valves are working
15. CLOU"Y PREFORMS
Dull color preforms.'ack of clarity.
Inefficient %rying
Blocked drier filters /ir leaks on te drier
/ir leaks on macineoppers
'ow air flow to drying opper
'ow process air temperature
Ceck drier temperature and dew point
Clean drier air filters
Ceck for air leaks on drier Ceck for air leaks on macine opper
Ceck air flow to opper
Increase drier process temperature
Increase barrel temperature
Sut macine down for 0 our and dry material
Increase back pressure
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Barrel temperature low
Insufficient drying
Back pressure low
16. HOLLOW !ATES
(ole in the center ofgate.
#olding pressure low
#old time low
Insufficient cooling time
#ig cavity eatertemperature
*oreign material in gate
Increase olding pressure
Increase olding time
Increase cooling time
'ower cavity eater temperature
Ceck for foreign material in gate area.
17. "ISCOLORE"PREFORMS
#ig barrel temperature
#ig mold temperature
#ig drying temperature
'ower barrel temperature
'ower injection mould temperature
'ower drier process temperature
18. O#ER FINISH Contaminated splits
'ow packing pressure
Insufficient packing time
Clean splits
Increase packing pressure
Increase packing time
19. BURNT !ATES #ig cavity temperature )educe cavity temperature
2. O#AL FINISH Insufficient cooling
#old time low
Insufficient cooling
#ig core and cavity temperatures
Increase cooling time
Increase injection old time
Ceck water temperature and water flow toinjection Mould
Ceck temperature of injection cores and
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cavities
21. !AS BURNS #ig injection speed
Contaminated splits
%ecrease injection speed
Clean splits
22. C$%&'( )*+,**-+$*%( 0 NSRH$-+%
Improper air venting in neckrings, causing melt flowune$ually and form a weldline at tis point.
Ceck e$ual air vents along te circumferenceof te neck ring core insert.
Clean dirt accumulations around vent area.
23. #*$+&% &$%&' - +*$*$ (:$%&*.
1+treme ig packing atneck finis area, leading toe+pansion crack.
More prevalent inunbalanced gating system.
)educe packing pressure.
)educe barrel & melt temperature.
24. HI!HACETAL"EHY"E
#ig residual // in resin
#ig barrel temperature
#ig back pressure
#ig screw speed
#ig injection speed
#ig mold manifoldtemperature
#ig nole tip temperature
'ong cycle time
#ig e+truder & screwcusion
Ceck for resin // levels
)educe te barrel temperature
)educe back pressure
)educe screw )PM
)educe injection speed
)educe mold manifold temperature
)educe cycle time
)educe cusion Increase inlet resin temperature
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'ow inlet resin temperature(nsuitable screw
TROUBLESHOOTING GUIDE
Stretc Blow MoldingProblem Possible causes Possible Solutions
1. PEARLESCENCE
2ite Pearl sade onte bottle surface.
Pearlescence results fromstretcing of moleculesfaster tan tey canrespond past it3s naturalstretc limit.
Small tears appear onmaterial surface.
4is can also be due tote Pre bottle condition
Material too tin at pearlescent area.
Increase eat oter tan were pearl isevident.
Material too tick at pearlescent area. Increase eat at pearl area.
Increase overall preform temperature.
Pearlescence on te bottle soulder may be teresult of a blow air leak troug nose from eiterpre-valve, ig blow valve or stretc rod.
)educe Pre blow volume, increase Pre blow
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considerably smaller tante mold cavity, 5 67 8.
time and reduce Pre blow pressure.
1nsure Pre blow bottle is not to large.
1+cessive petal formation in Pre blow will cause
pearl in te petal area. Pearlescence in te body in te form of a ring is
te result of insufficient Pre blow.2. EXCESSIVE FILL
POINT ROP
'ow fill volume of tebottle
'ow levels of orientationresults in te material notaving enoug strengt toresist te stretc force.
)educe over all perform temperature allowingte bottle to be blown closer to its natural stretclimit. (nder tis condition sligt pearlescencemay be evident
!. CLEAR "REA# ALON$
NSR % rou&h 'ee( the crac)sur'ace*
2eld line formation along
tis circumference due tolow melt temperature, lowfill velocity, improperventing. !Preform defect"
Ceck 9Preform Problem : )emedy; point no.66.
4ere may be cances a fine crack at injectionmolding stage, is not noticed. Ceck crackpresence by polaried ligt table.
Problem Possible causes Possible Solutions4. BURST BELOW NSR
(smooth feel of crack
surface)
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PRESS-RE %"ASE* te gate
'ow I>
1+cessive stress inpreform
e+cessive stress
Increase eat below te preform
Stretc rod clearance too sort.
)eset stretc rod clearance. )educe stretc rod pressure.
0. EAV "ASE ,EI$T Incorrect eating profile,resulting in a poordistribution of material.
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14. S,-N$ $ATE *irst impacted mark isevident and is notcentered to te gate, an
alignment problem isusually te cause.
Misalignment of te preform to te mould, noleor stretc rod.
Inade$uate mouldcooling, If te gate iscentered to te stretcrod impact mark and yetnot centered to te mouldbase at te end of blow.
Ceck blow mould cooling
'ower alf of preform too ot
If te first impact mark iscentered, te stretc rod
as lost control of tegateduring blow.
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STRETC RO preform end cap, materialwraps around te end ofte stretc rod. In effect
anoter tick& tintransition forms
Increase pre blow pressure.
)educe stretc rod pressure.
12. "LO,N FINIS
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Problem Possible causes Possible Solutions1+. "ENT NEC# Misalignment of te
preform to te mould ornose.
%istortion below teflange
Insufficient mouldcooling
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preform outsidesurface for te amountof eat absorbed by
te P.1.4.
Increase air circulation troug oven.
Increase blower speed, clean blowers
Problem Possible causes Possible Solutions1. FLAT SIES Poor venting of mold. 1nsure ade$uate mold venting, and clean clogs.
Increase low blow pressure ensuring bottlediameter is close to blow mould sie.
'ow blow bottle too small. In tis case tevolume of air trying to escape during ig blow ismore tan te venting can allow.
'ow blow bottle blown to fast.
1+cessive ig blow pressure at te end of lowblow to minimie air tat remains in te blowmould before ig blow starts.
)educe low blow pressure and e+tend low blowtime if te body of te bottle as reaced temould.
)educe ig blow pressure.13. EFOR5ATION AT
5O-L PARTIN$
LINES
Pressure remaining in tebottle wen blow mouldsopen.
Insufficient ig blow &cooling time
Material too ot and&or
Inade$uate e+aust time, ceck e+aust valveactivation.
Increase ig blow time or reduce materialtickness
)educe material tickness
)educe preform temperature
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too
tick24. COC#E "O Insufficient or no low
blow Insufficient eat beside
coke
Increase low blow pressure
Increase eat in te body )educe eat in te base and& or neck.
)educe air delay time
)educe stretc rod pressure
Problem Possible causes Possible Solutions21. LI$T "ASE ,EI$T Poor eating profileresulting in poordistribution of material,insufficient stretcing ofte body or soulder.
)educe eat near te base of te preform untilpearlescence occurs ten increase eat to tesoulder and body. )epeat until base weigt iscorrect
Increase air delay time
Increase stretc rod pressure
)educe low blow pressure
)educe oven sielding of te taper
22. NOT F-LL FOR5E
Insufficient ig blowpressure.
)ate of ig blow tooslow, materialmovement stallsbefore reacing tecorners.
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2/. FOL IN "ASE AT
EN CAP LINE Preform temperature
too ot
Preform end cap area
to cold /n e+cess of material
in te vicinity of tefold
'ack or loss of lowblow volume
1+cessive force appliedby te stretc rod
/ged or stressedpreforms
)educe eat in te areas oter tan te base. Ifte fold remains after pearlescence as formed.#eat may be applied to te preform end cap
area. Increase low blow pressure
)educe air delay time
)educe stretc rod pressure
20. CRAC#E "ASE Preform end cap toocold
1+cessive stretc rodpressure
Clearance between testretc rod and mouldbase too small
4ick crystallinityabove te gate
Increase eat beside or below te gate
)educe stretc rod pressure
Ceck preform for e+cessive crystallinity, if socange preforms.
Increase stretc rod, mould base gap
Problem Possible causes Possible Solutions2. STRESS CRAC#IN$
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cange. /s clearancedeteriorates web sapecanges increasing te
risk of stress cracking. 4emperature of te
lower alf of tepreform3s body is tooig.
Cemical reaction bysome line lubricants.
'ow I.>. material
'igt base weigt.Inade$uate tickness
to resist movement.
'ine lubricants generally cause severe stresscracking in all feet.
Increase base weigt
23. EXPLOSIONS -RIN$
"LO,IN$.
#ot bottles !)efer #otBottles"
*olds in te base
'igt base weigt
1+cessive post mouldgrowt
'ow I.>.
Contamination
/ir bubbles above tegate
)efer Causes
Stress Cracking
Cracked bases
1+cessive crystallinity
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