pi trouble shooting

7/31/2019 PI Trouble Shooting

1/9

1. Short Shot # Add gate(s)

Cavities are not filled completely.

c. Injection power is # Use machine with higher pressur

a. Shot volume are # Increase shot size unsufficient

not enough # Decrease holding transfer position

# Increase back pressure d. Material has low # Use high flow material

# Decrease screw rotation fluidity # Increase product thickness

# Decrease temperature at hopper throat

e. Material has low # Provide gas vent

b. Material has low # Increase cylinder temperature fluidity 1 # Change gate location

fluidity 1 # Increase mold temperature # Dry the material enough

# Increase back pressure

# Increase screw rotation ( amorphous) f. Gate balance is # Adjust gate balance

# Decrease back pressure (crystalline) poor

c. Material has low # Increase injection speed g. Others # Check nozzle heater connection

fluidity 2 # Increase injection pressure # Check distribution of mold tempe

# Increase holding pressure # Check and clean screw/cylinder

2. Flash

d. Air inside cavity is # Decrease injection speed Material come out from cavity through parting line.

trapped # Decrease clamp force

# Increase holding pressure transfer a. Clamping force is # Increase clamping force

position small # Decrease injection pressure

# Decrease injection speed

# Decrease holding pressure

a. Shot volume are # Check material feeding

not enough # Use machine with proper injection b. Material has too # Decrease holding pressure

volume high fluidity # Decrease injection pressure

# Check check ring # Decrease injection speed

# Decrease cylinder temperature

b. Excessive flow # Enlarge area of sprue, runner and gate # Decrease mold temperature

restriction in mold # Increase product thickness 1 # Decrease screw rotation (amorp

# Increase screw rotation (crystalline) 3. Sink mark

# Increase holding pressure transfer Dent appear(s) on product

position

c. Material has low # Increase cylinder temperature a. Shrinkage is too # Increase holding pressure

fluidity 1 # Increase mold temperature much # Increase holding time

# Increase back pressure # Decrease holding pressure trans

# Increase screw rotation (amorphous) position

# Decrease screw rotation (crystalline) # Increase injection pressure

# Decrease injection speed

d. Material has low # Increaase injection speed # Decrease mold temperature

low fluidity 2 # Increase injection pressure # Decrease cylinder temperature

# Increase holding pressure

b. Shot volume is not # Keep cushion

e. Shot size is too # Increase holding pressure transfer enough # Increase holding pressure

large position # Increase holding time


# Increase injection pressure

a. Parting line is # Check if it dent or something stuck in the # Increase injection speed

wrong mold # Increase mold temperature

# Check parallelism of injection molding # Increase cylinder temperature

machine

# Check engagement of parting face

# Check parallelism of mold a. Shrinkage is too # Enlarge area of sprue, runner an

b. Clamping force is # Use machine with proper clamping force much # Use high flow material

small # Use machine with higher pressu

c. Mold strength is # Increase mold strength/rigidity b. Product have # Provide rib

Remedy

except (not related to setting parameters)


Cause


Remedy

Cause Remedy

Cause


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4. Weld line 5. Silver streak

Thin line appear(s) because material is divided and meets Milky silver streak(s) appear in the direction of flow

again with partial fusion during filling

a. Gas is generated # Decrease cylinder temperature

a. Material has low # Increase cylinder temperature # Increase screw rotation delay

fluidity 1 # Increase mold temperature # Increase back pressure (when ga

# Increase back pressure doesn't escape)

# Increase screw rotation (amorphous) # Decrease back pressure (when m

# Decrease screw rotation (crystalline) rial decomposes)

b. Material has low # Increase injection speed b. Air is trapped # Change injection pattern

fluidity 2 # Increase injection pressure # Decrease suck back stroke

# Increase holding pressure # Decrease suck back speed

# Decrease screw rotation

c. Air inside the # Decrease injection speed

cavity is trapped # Decrease clamping force c. Heat is generated # Decrease injection speed

# Increase holding pressure transfer by shearing at # Increase cylinder temperature

position nozzle and gate # Increase mold temperature

# Decrease holding pressure

d. [Make the line non- # Increase holding pressure

noticeable] # Increase holding time d. Moisture is # Increase temperature at hopper

# Increase mold temperature involved

# Change injection speed position pattern

to change weld line location e. Unmelt material is # Increase mold temperature

fill into cavity # Increase back pressure

# Increase cylinder temperature

a. Air inside the # Provide gas vent # Increase screw rotation (amorph

is trapped # Change gate location # Decrease screw rotation (crystal

# Dry the material enough

f. Cold slug appears # Do the same countermeasure as

b. Gate location is # Change gate location in cavity slug

incorrect # Change gate number 5

6. Flow mark

a. Air is trapped # Change gate location Mark like annual ring appears perpendicular to flow

# Provide gas vent

# Dry the material enough a. Filling speed is to # Increase injection speed

low # Decrease holding pressure trans

b. Heat is generated # Enlarge area of nozzle and gate position

by shearing at # Increase injection pressure

nozzle and gate

b. Air inside cavity # Decrease injection speed

c. Gas is generated # Use less mold release agent is trapped # Decrease clamping force

# Provide gas vent # Increase holding pressure transf

# Use vented barrel position

# Dry material enough

# Use dehumidifying dryer c. Material has low # Increase cylinder temperature

fluidity 1 # Increase mold temperature

d. Different materials # Purge material enough # Increase back pressure

is involved # Handle material carefully so ambient air # Increase screw rotation (amorph

couldn't entering the material bag # Decrease screw rotation (crystal

e. Cavity surface is # Check and clean cavity d. Material has low # Increase injection speed

dirty fluidity 2 # Decrease mold temperature

f. Materials degrades # Use smaller screw/cylinder e. Cold slug appears # Do the same countermeasure as

because of long in cavity slug

residence time in

cylinder

a Air inside cavity # Provide gas vent


Cause Remedy


Cause Remedy


Cause Remedy


3/9

7. Cloud/haze b. Air is trapped in # Change gate location

Dim mark, different from original gloss, appears on products the mold # Provide gas vent


a. Mold temperature # Increase injection speed

is low # Increase mold temperature c. Gas is generated # Use less mold release agent

# Increase cylinder temperature # Provide gas vent

# Increase injection pressure # Use vented barrel


b. Air is trapped in # Change injection pattern # Use dehumidifying dryer

the mold # Decrease suckback stroke

# Decrease suckback speed d. Cavity profile is # Make terrace portion shorter

# Decrease screw rotation incorrect # Round edge portion

c. Gas is generated # Decrease cylinder temperature 8. Cold slug

# Increase screw rotation delay The cold material at nozzle front comes into cavity and

# Increase back pressure (when gas shows uneven gloss.

doesn't escape)

# Decrease back pressure (when mate- a. Material drol l into # Increase nozzle temperature

rial decomposes) cavity # Mold with shift molding

# Decrease screw rotaion # Decrease nozzle temperature

d. Cold slug is # Do the same counter measure as b. Cold slug is not # Decrease injection speed

appear in cavity cold slug trapped at slug

well

e. [In case of gloss # Increase holding pressure transfer

at textured area] position c. [Make cold slug # Increase mold temperature

non-noticeable] # Increase injection speed


a. Polishing of mold # Check cavity surface # Increase cylinder temperature

is not enough # Increase screw rotation (amorph

# Decrease screw rotation (crystal

9

9. Jetting c. Ejector stroke is # Increase ejector speed

Material like string comes into cavity and string mark remains not enough

after cooling.

d. Because short # Do the same counter measure a

a. Speed at gate is # Decrease injection speed shot occurs shot

high # Decrease mold temperature

e. Because warpage # Do the same countermeasure as

b. Cold slug appears # Do the same countermeasure as cold occurs warpage

in cavity slug

c. [Make jetting non- # Increase mold temperature a. Draft is unsuffici- # Increase draft angle

noticeable] # Increase injection speed ent # Diminish undercut


# Increase cylinder temperature b. Ejector pin location # Change pin location

# Increase screw rotation (amorphous) is not correct

# Decrease screw rotation (cystalline)

# Increase injection speed very high c. Ejector structure # Check ejector plate incline

is incorrect # Use stripper plate

# Use single eject pin

a. Gate is incorrect # Change gate location

# Change gate area d. Nozzle alignment # Check nozzle alignment

# Change gate type is poor

10. Eject failure e. Cavity surface is # Check for flaw and rust at cavity

Product remain inside the mold or are broken by ejector pin wrong polish cavity well

at ejection.

a. Cooling is not # Increase cooling time f. Different material # Purge material enough

Remedy



Cause Remedy

Cause Remedy


Cause


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h. Product is stick in # Use mold release agent # Increase screw rotation (amorph

cavity # Provide ventilation port # Decrease screw rotation (crystal

# Enlarge ejector pin clearance

# Use air jet d. Reduce deforma- # Increase cooling time

tion

11. Warpage

Product are deformed after ejection e. Parts ejection is # Do the same counter measure a

difficult failure

a. Pressure distribu- # Decrease holding pressure

tion is not even # Decrease holding time

# Increase holding pressure transfer a. Pressure distribu- # Change gate location

position tion is uneven # Change gate number

# Increase injection speed (when low # Change gate size

flow) # Use high flow material

# Decrease injection speed (when high # Increase product thickness

flow)

# Decrease injection pressure b. Strain is genera- # Change cooling channel

# Increase mold temperature ted by cooling # Change mold material

# Increase back pressure # Reduce thickness difference of p

# Increase screw rotation (amorphous)

# Decrease screw rotation (crystalline)

b. Strain is genera- # Decrease injection speed

ted by orientation # Increase mold temperature


c. Strain si genera- # Increase holding pressure

ted by cooling # Increase injection speed

# Decrease holding pressure transfer

position

# Change mold temperature

# Increase back pressure 13

12. Void/bubble # Increase back pressure (when ga

Void/bubble appears inside doesn't escape)

# Decrease back pressure (when m

a. Shrinkage is too # Increase holding pressure rial decomposed)

much # Increase holding time # Decrease screw rotation

# Increase holding pressure transfer

position a. Shrinkage is too # Enlarge area of sprue and gate

# Increase injection pressure much # Use high flow material

# Decrease injection speed # Use machine with higher pressu

# Decrease mold temperature

# Decrease cylinder temperature b. Air is trapped # Change gate location

# Provide gas vent

b. Shot volume si not # Keep cushion # Use vented barrel

enough # Increase holding pressure # Dry the material enough

# Increase holding time # Use dehumidfying dryer


# Increase injection pressure c. Product have un- # Provide ribs

# Increase injection speed even thickness # Decrease products thickness

# Increase mold temperature


c. Uneven cooling # Increase mold temperature

# Increase injection speed

# Increase cooling time

d. Air is trapped # Change injection pattern

# Decrease suck back stroke

Cause Remedy


Cause Remedy



5/9

13. Crazing 14. Burning

Product are crazing or cracking Material has burns because of high temeperature result

from shearing and compression

a. Residual stress # Decrease injection speed

are occurs # Decrease holding pressure a. Heat is generated # Decrease injection speed

because of high # Decrease injection speed by shearing at no- # Increase mold temperature

pressure # Increase holding pressure transfer zzle and gate # Increasse cylinder temperature

position # Decrease holding pressure

b. Material has low # Increase cylinder temperature b. Air inside the ca- # Decrease injection speed

fluidity # Increase mold temperature vity is trapped # Decrease clamping force

# Increase back pressure # Increase holding pressure transf

# Increase screw rotation (amorphous) position

# Decrrease screw rotaion (crystalline)

c. Material decompo- # Decrease cylinder temperature

c. Part ejection is # Do the same countermeasure as eject ses at high tempe- # Increase screw rotation delay tim

difficult failure ture # Decrease screw rotation

# Decrease back pressure

a. Residual stress # Change gate location d. Screw goes back # Increase back pressure

occurs # Change gate number without feeding # Increase cylinder temperature (c

# Change gate size material lline)

# Decrease cylinder temperature (

b. Material has low # Use high flow material phous)

fluidity # Increase product thickness

e. Cold slug appears # Do the same counter measure a

in cavity slug

a. Heat is generated # Enlarge area of nozzle and gate

by shearing at no-

17 zzle and gate

b. Heat is generated # Check cylinder temperature controller 15. White brush mark

by shearing du- # Provide cylinder cooling White marks appears on part surface

ring screw rota- # Change material a. Residual stress # Decrease injection pressure

tion occurs because # Decrease holding pressure

of high pressure # Decrease holding time

c. Air inside cavity is # Provide gas vent # Decrease injection speed

trapped # Change gate location # Increase holding pressure transf

# Dry material enough position

d. Material degrades # Use smaller screw cylinder b. Material has low # Increase cylinder temperature

because of long fluidity 1 # Increase mold temperature

residence time in

cylinder

e. Different material # Purge material enough

is involved # Handle material carefully # Increase back pressure

# Increase screw rotation (amorph

f. Others # Check nozzle heater connection # Decrease screw rotation (crystal

# Check mold temeprature distribution

# Check and clean cylinder c. Parts ejection is # Do the same counter measure a

difficult failure

a. Residual stress # Change gate location

occurs # Change gate number

# Change gate size

b Material has low # Use high flow material

Remedy


Cause Remedy

Cause




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