Troubleshooting Guide PET

8/13/2019 Troubleshooting Guide PET

1/17

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

Page 61 Customer Technical Service

+91-9933035193


2/17


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 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


Injection speed low

%rier inefficient Back pressure low

Increase injection pressure

Increase mould temperature


Increase injection speed

Ceck resin drier


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


+91-9933035193


3/17


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


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


+91-9933035193


4/17


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


'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 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


Sut macine down for 0 our and dry material



+91-9933035193


5/17



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


'ower cavity eater temperature

Ceck for foreign material in gate area.

17. "ISCOLORE"PREFORMS



#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 injection old time

Ceck water temperature and water flow toinjection Mould

Ceck temperature of injection cores and


+91-9933035193


6/17


cavities

21. !AS BURNS #ig injection speed

Contaminated splits


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 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


+91-9933035193


7/17


'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


+91-9933035193


8/17


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)


9/17


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.


10/17


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.


11/17


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


12/17


Problem Possible causes Possible Solutions1+. "ENT NEC# Misalignment of te

preform to te mould ornose.

%istortion below teflange

Insufficient mouldcooling


13/17


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


+91-9933035193


14/17


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.


15/17


16/17


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


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


Ceck preform for e+cessive crystallinity, if socange preforms.

Increase stretc rod, mould base gap

Problem Possible causes Possible Solutions2. STRESS CRAC#IN$


17/17


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


+91-9933035193

Date post:	04-Jun-2018
Category:	Documents
Upload:	edgard-quispe
View:	247 times
Download:	1 times

Troubleshooting Guide PET

Documents