1. Injection Moulding Technology Mould Design & Construction
Part 3
Mould Design & Construction
READ.

2. Session aim
To gain an understanding of general mould design and construction techniques, and to become familiar with the purpose and function of the various component parts.
READ.

3. READ. Session objectives
By the end of the session you will be able to:
Detail the requirement for venting the mould.
Identify the component parts of a two plate mould.
List two advantages and limitations for various gate
design alternatives.
State the three elements of the feed system.
Identify applications for typical runner less mould
designs.
Explain the importance of mould temperature
control.
READ.

4. IMAGINE YOUR MOULD DESIGNERS. WHAT NEEDS TO BE CONSIDERED?
life
Mould
material
Cost
restraints
Mould
Design
Moulding
machine
Component
detail
Quantity
Component
material
IMAGINE YOUR MOULD DESIGNERS.
WHAT NEEDS TO BE CONSIDERED?
BRAINSTORM!
Mould
making
techniques
Post
moulding
operations

5. READ. Two Plate Mould Tool Support blocks and risers Core plate
Split line
Moving backplate
Two Plate Mould Tool
Push back pin
Cavity plate
Ejector pin
Fixed back plate
Sprue puller pin
Locating ring
Cold
Slug
Well
READ.
Sprue bush
Runner
Sprue
Ejector plate
Cooling channel
Air vent
Dowel or Guide pin
Guide bush

6. Question 1 List the advantages & disadvantages of a multi-plate mould?

7. Multi-plate mould tool
3RD DAYLIGHT STIPS SPRUE.
EJECTS COMPONENT.

8. Multi-plate mould tool
Advantages
Centre gating of multi cavity.
Side gating easily achieved.
Multi-point gating easily
achieved.
Automatic de-gating.
Disadvantages
ASK DELEGATES?
Higher cost of tooling.
More moving parts.
Critical opening stroke.
Runner wastage.
Stripper plate

9. Question 2 On a mould that incorporates a hot runner, what might soft start facility be used for?

10. Hot runner
READ

12. ASK DELEGATES THE FOUR ZONES.
The hot runner
Ideally the sprue
bush, hot tips
and the manifold
should have
separate
controllers and
thermocouples.
On the example
four zones
are required.
READ.
ASK DELEGATES THE FOUR ZONES.

13. READ. DISADVANTAGE. ADVANTAGE. DESCRIBE.
Hot runner systems
The 2 plate tool
Increases the
mould height.
Saved material
waste from the
sprue & runner.
READ.
DISADVANTAGE.
ADVANTAGE.
DESCRIBE.
Material delivered to the cavities in the same condition as the melt left
the barrel.

14. Question 3 Please list 3 advantages and 3 limitations when using hot runner moulds?

15. Limitations of a hot runner
Increased set-up times.
Warm up period required.
Increased tooling costs.
Manifold leaks.
Higher maintenance costs.
Degradation with certain polymers.
Heat expansion problems.
READ.
SOFT START!
CARTRIDGE HEATERS ABSORB MOISTURE AS THEY COOL.

16. When a hot runner leaks ….it leaks !

17. Advantages of a hot runner
No feed system to be removed.
Reduced mould open stroke.
Reduced shot weight.
Injection time reduced.
Automatic de-gating.
Easier to balance gates.
Increased number of cavities possible.
ASK DELEGATES.
READ.

18. When using hot runner moulds
Avoid regrind to avoid blocked nozzles.
Avoid heat sensitive polymers.
Do not flick off cold slugs.
Keep systems fully maintained.
READ.

19. Question 4 What is the primary function of a stack mould?

20. Stack mould - reduced projected area
Braun Ireland
DESCRIBE.
WHY DO WE USE.
TO REDUCE PROJECTED AREA.
WEVE SEEN AIR EJECTION CAN YOU NAME ANY OTHERS.

22. Valve to Valve

23. Spring opening

24. Question 5 What are the different types of ejector pins and methods of ejection?

25. Combination round/blade ejection
Blade ejectors
DESCRIBE WHY WE USE.
USE PROPS.
Round ejectors

26. USED TO PRODUCE CORE IN MOULDING.
Sleeve ejection
Core pin
Sleeve
DESCRIBE.
USE PROPS.
USED TO PRODUCE CORE IN MOULDING.

27. PIN STAYS STILL SLEEVE COMES FORWARD.
Sleeve ejection
Good even ejection
around bosses but
quite expensive.
PIN STAYS STILL SLEEVE COMES FORWARD.

28. Stripper plate ejection
Stripper block
ASK DELEGATES.
DISADVANTAGE.
CAN’T SHORT SHOT.
ADVANTAGE.
LEAVES NO WITNESS MARKS.

29. USED USUALLY WITH STIPPER PLATES ON DEEP DRAWN COMPONENTS.
Air ejection
DESCRIBE.
USED USUALLY WITH STIPPER PLATES ON DEEP DRAWN COMPONENTS.
BUCKETS, BOWLS, BINS.
Air off - spring returns valve to its rear position

30. Question 6 When would mechanical or hydraulic core movement be used?

31. Mechanical core pin movement
READ

32. HYDRAULIC CYLINDERS CAN MOVE CORES.
Core pulling
HYDRAULIC CYLINDERS CAN MOVE CORES.
MORE EXPENSIVE.

33. Core movement by hydraulics
Points to remember:
Machines will need to be programmed.
There are many different sequences.
Must know the sequence, before opening or
closing the mould.
READ.
WRITE ON BOARD COMMON CORE SEQUENCES.
TOOLS ARE EXPENSIVE.
IF TIME.
GO TO BALCONY.
BREAK 3.10.
If in doubt ASK!

34. Question 7 When designing a mould, utilising a cold runner system, what are the primary considerations to be addressed?

35. NAME PARTS. SPRUE, RUNNER, GATE.
The feed system
NAME PARTS.
SPRUE,
RUNNER,
GATE.

36. COLD POINTS. MISS MATCH. MODIFIED TRAPIZOIDAL.
Runner shape
Which shape will give the best flow?
10 deg
COLD POINTS.
MISS MATCH.
MODIFIED TRAPIZOIDAL.

37. IS THIS A GOOD RUNNER LAYOUT?
EXPLAIN WHY.

38. Runner layout

39. General guidelines Single Mould
As the number of cavities increases, so must the machine tonnage
2,4,6,8,12,16,24,32,48,64 cavities are typical. No odd numbers!

40. Question 8 Please list advantages & disadvantages for the selected gates:
Sprue gate
Pin gate
Diaphragm gate
Tab gate
Flash gate
Fan gate
Tunnel gate

41. ADVANTAGES / DISADVANTAGES. SPRUE =GOOD FILL-LARGE WITNESS
Gates
Sprue gate
Diaphragm gate
Pin gate
Flash gate
Fan gate
Tab gate
ASK DELEGATES.
ADVANTAGES / DISADVANTAGES.
SPRUE =GOOD FILL-LARGE WITNESS
PIN =NO WITNESS+SHORT FREEZE OFF TIME.
DIAPHRAGM =EVEN FILL-NEEDS SECOND OP.
TAB =ABS-JETTING

42. Submarine/tunnel gate
Sprue
Runner
Component
ASK DELEGATES.
WHY DO WE USE?
Gate

43. Submarine/tunnel gate
SELF DEGATING.
NO WITNESS MARKS.

44. SIZE SMALLER. FEED FREEZE OFF.
Gate considerations
Size in relation to section thickness of the moulding.
Always feed into the thickest section.
Position gate to give even filling.
SIZE SMALLER.
FEED FREEZE OFF.

45. Question 9 Why is mould venting required?

46. ASK DELEGATES. Mould venting To prevent burning/dieseling.
Exhaust grooves
Vent depth 0.025mm
To prevent burning/dieseling.
ASK DELEGATES.

47. Question 10 What are the general considerations for the correct moulding temperature?

48. Mould temperature control
High enough to allow filling of the mould, without
premature freezing of the polymer melt.
As uniform as possible, to ensure the mould is
cooled equally in all areas.
Mould temperature has the greatest influence
on part quality.
READ.

49. Piping up considerations
ASK DELEGATES CORRECT WAY TO PIPE UP.
1in
2in
1out
2out

50. Cool core pin technology
Coolant flow
Used as an alternative
to cooling channels.
BERILIUM.
MOULDMAX.
USED WERE CHANNELS CANT BE PUT.
Core

51. Beryllium copper insert to improve cooling
READ

52. Cooling baffles Baffles may be offset to achieve turbulent flow.
Must be piped correctly.

53. Spiral flow cooling out in out in Material entering the mould
will be at
its
hottest in
out in

54. Machine Practical 1

55. Injection Moulding Technology Mould Design & Construction
Part 3
Mould Design & Construction
READ

56. Injection Moulding Technology
Part 3
Plastics Materials

57. Aim
To provide an understanding of plastics materials technology and processing behaviour when injection moulded.

58. Objectives By the end of the session you will be able to:
Describe, in simple terms, the molecular structure
of plastics materials.
State three methods of classifying plastics,
giving examples.
Describe the MFI test and it’s relevance.
Identify five common additives to modern plastics.

59. What are plastics? Synthetic - Man made Organic - Based on carbon
Polymers -
Describes the MOLECULES of polymers
Many units
To show that polymers are based on oil by-products hence when PP degrades or is over heated it returns to an oil like substance

60. Polymerisation exampleH H c H c H c H c H H
Example
ETHYLENE
Monomer

61. Polymerisation example
Catalyst -
heat, pressure and time c H H c c
Heat and pressure in side reaction vessel
Initiator starts reaction
Monomer units start to link together
Reaction continues in a random manner but must be controlled
Terminator added to stop reaction giviong polymer chains of similar length – Molecular weight distribution
ETHYLENE
monomer
POLYETHYLENE
polymer

62. Polymer examples Propylene monomer Polypropylene polymer Styrene
Polystyrene
polymer
Vinyl Chloride
monomer
Polyvinylchloride
polymer
Sequence first monomer to polymer for PP and PS
Next two start with Polymer to monomer – get delegates to think what monomer you start with.
Polycarbonate – this is to demo that not all polymers follow the same route.
In the case of polycarbonate:
Produced by polycondesnation from Bisphenol A – this is manufactured by mixing phenol, acetone and phosgene
Phosgene
Bis-Phenol Acetone
monomer
Polycarbonate
polymer

63. Summary Polymer chains have a coiled spring like structure.
Picture shows the chain in reality – not just a line drawing it’s a 3D structure
Demo spring like structure of polymer in real terms
Discuss length of chains, size of atoms, behaviour in mould – spring stretches during injection relaxes, recoils as it cools hence shrinkage
About 5,000 times longer than their diameter.
Chains are upwards of 1,000,000 repeat units long.
Processing of polymers reduces the chain length and
hence the loss of properties when using regrind.

64. Curing/solidification Cross-linking reaction
Classifying plastics
Thermosets
Example - Bakelite
Flows due to pressure
Heat
Melt
Curing/solidification
Heat & Pressure
Cross-linking reaction
Thermoset materials
Warm barrel 100 to 150, hot tool 150 to 200
Soften polymer so it will flow, force into mould, under pressure and heat chemical reaction occurs
Cross-links – chicken wire effect – can not be reversed
Some thermosets such as expoy resin require a catalyste to start reaction e.g Araldite two part epoxy resin, mix the two elements reaction occurs cross links are formed

65. Classifying plastics Thermosetting Bakelite Rubber Epoxy Melamine
Polyester
(Chemical change - Boiled egg)
PET (Polyester) in both lists since it is possible eto have both a Thermoset PET – car body repair kits and a thermoplastic PET for bottles.

66. Example - Polyethylene
Classifying plastics
Thermoplastics
Example - Polyethylene
Melt
Flows under
pressure
Heat
Cool/remove heat
Solidification
PET (Polyester) in both lists since it is possible eto have both a Thermoset PET – car body repair kits and a thermoplastic PET for bottles.
Thermmoplastics – hot barrel / cooler tool
Some interaction or bonds between chains such as Van der Waals forces, entanglement, structure but can be reversed when heat applied

67. Classifying plastics Thermoplastics Polyethylene Polystyrene
Polycarbonate
Nylon
Polyester
(Physical change - Ice to water)
PET (Polyester) in both lists since it is possible to have both a thermoset PET – car body repair kits and a thermoplastic PET for bottles.
Discuss Thermopastic Elastomers – rubber type properties but can be processed on a thermoplastic machine, structural difference gives rise to hard and soft domains – Two shot machine

68. Classifying plastics
Commodity
Engineering

69. Prices are only approximate
Classifying plastics
Commodity
Price/tonne
Plastic
Polypropylene
HDPE
LDPE
Polystyrene
SAN
Acrylic
ABS
£600 - £950
£500 - £900
£600 - £900
£600 - £1200
£900 - £1500
£ £2500
Commodity plastics
High volume parts
Disposable goods / packaging industry
Service properties low
Low strength / heat resistance / chemical resistance etc.
High volume production of polymer hence low cost
Prices are only approximate

70. Classifying plastics Engineering Plastic Price/tonne
PET
Acetal (POM)
Nylon (PA)
PBT PC
PAI
PEEK
£ £1200
£ £1900
£ £2400
£ £2700
£ £3500
£ £40000
£ £69000
Engineering materials will have much better mechcanical properties such as tensile strength, a high strength to weight ratio, good chemical resistance and much more expensive
PEEK - £4,500 per tonne
Manifold PA66 GF35
Prices are only approximate.

71. Amorphous versus Semi-crystalline! What are the differences?
Classifying plastics
Amorphous versus Semi-crystalline!
What are the differences?
Engineering materials will have much better mechcanical properties such as tensile strength, a high strength to weight ratio, good chemical resistance and much more expensive
PEEK - £4,500 per tonne

72. Structural changes of polymers
Molten state
Flow
COOL
Amorphous
Random structure
Semi-Crystalline
Ordered structure

73. Classifying plastics Thermoplastics Amorphous Semi-crystalline
Polycarbonate
A.B.S.
Polystyrene
S.A.N.
Acrylic
Polyethylene
Polypropylene
Nylon
Acetal
Polyester
Introduce concept of amorphous and semi-crystalline sub-divisions of thermoplastics

74. Why is crystallinity important?
Property differences
Why is crystallinity important?
Amorphous
Semi-crystalline
Generally clear
Generally opaque
High mould Shrinkage
1.5%-2.5%
Low mould shrinkage
0.5%
Wide melting range
Narrow melting range

75. + Flow behaviour Semi-crystalline Ease Amorphous of flow Temperature
Amorphous plastics
Melt and solidify over a
WIDE temperature range.
(PA) +
Ease of
flow
Temperature
Amorphous
Semi-crystalline plastics
Melt and solidify over a
NARROW temperature
range. (i.e they have a crystalline melting point)
(PMMA)

76. Examples: HDPE, PA, POM, PVC, PS, PP.
Homo-polymers
The homo-polymer chains comprise of the same repeat unit for their entire length.
Examples: HDPE, PA, POM, PVC, PS, PP.

77. Co-polymers
Co-polymer chains comprise of two or more different repeat units, which are linked together.
Examples: ABS, SAN, POM, PP, HIPS.
(ABS – Acrylonitrile-Butadiene-Styrene)
Mention Co-polymers can be symmetrical, random or branched use white baord to illustartae
Ratio of component polymers changed to give different properties I.e ABS increase Butadiene to give greater impact strength, increase Acrylonitrile for chemical resistance this leads to a range of grades of ABS being available fro the supplier.

78. High Impact Polystyrene
Blends & Alloys
Blends
Two or more different polymers in the same matrix but not linked.
Noryl
PPO/PS
HIPS
High Impact Polystyrene
Alloys
Two or more different polymers in the same matrix plus a chemically adhesive additive.
Xenoy
Bayblend
PC/PBT
PC/ABS

79. Additives in polymers Why use additives?
Modify service performance.
Modify processing performance.

80. Types of additives Assist processing Heat stabilisers Lubricants
Essential additives
Modify bulk mechanical properties
Plasticisers
Reinforcing fillers
Toughening agents
= Flexible PVC
Reduce costs???
Powdered fillers e.g. talc or chalk

81. Additional additives Modify surface properties Anti-static agents
Modify optical properties
Pigments and dyes
Prevent ageing
U.V. stabiliser
Others
Blowing agents
Flame retardants

82. Melt Flow Index apparatus (MFI)

83. Melt Flow Index apparatus
Weight
Thermometer inside
an oil filled well
Barrel
Insulation
Polymer Melt
Avg. weight of extruded plastic in 10 mins.
Die

84. Effects of processing Chain length First pass Lower viscosity
Higher MFI
Lower strength material
Chain lengths can be shortened by processing or regrinding.

85. Melt Flow Index Summary The bigger the value - the easier the flow.
Values can reflect relative chain lengths.
Low shear (not representative of injection moulding)
Spiral flow test better.
Used as a quality control for incoming material.
Specific test conditions must be used.

86. Common trade names Trade names Family names Cycolac, Lustran, Terluran
ABS
Delrin, Hostaform, Kematal
Acetal (POM)
Plexiglas, Lucite (Perspex)
Acrylic (PMMA)
Lupolen, Rigidex, Vestolen
HDPE
Make reference to grades e.g.: Nylon 6 / 66
Styron, Lacqrene
HIPS
Ultramid A, Zytel 66, Maranyl A
Nylon 66 (PA 66)
Santoprene, EPDM
TPE’s

87. Pre-treatment of plastics
Moisture absorption - Hygroscopic
POM, PE, PP, PS, PVC
Not affected - drying not usually required.
PMMA, ABS, SAN, PP + talc
Water absorbed - may need drying.
Do not forget to mention that certain additives may require drying I.e. Talc fillers
Use coaster from dupont one moulded dry condition and one moulded without drying
Dry part – tough / strong
Wet part – visual no diffenerce, will break very easily
SAFE – MUST WEAR GLOVES TO DO DEMO POTENTIAL FOR INJURY
Last class all polymers in this list are oxidised or attacked by moisture if processed in damp condition this damages the chain and therefore the mechcanical properties PC is the same
PC, PET, PA, PBT, PUR
Damaged by water - needs drying.

88. Pre-treatment of plastics
Methods for removing moisture:
Vacuum oven
Dehumidifying dryer
Do not forget to mention that certain additives may require drying I.e. Talc fillers

89. Pre-treatment of plastics
Key drying considerations:
Type of material – ABS, PC, PA plus virgin or regrind.
Temperature and time required.
Volume held in dryer to give correct throughput.
Maintenance of dryer.
Do not forget to mention that certain additives may require drying I.e. Talc fillers

90. Injection Moulding Technology
Part 3
Plastics Materials

91. Injection Moulding Technology Processing & Troubleshooting
Part 3
Processing & Troubleshooting

92. Processing

93. Aims during the injection phase
Start Mould Safety
Apply Locking Tonnage
Open
Period
Mould
Closes
Injection Speed
& Pressure
Mould
Opens
Injection
Phase
Mould
99% Full
Holding
Phase
Cooling
Phase

94. Mould fill analysis

95. Melt flow behaviour
Frozen layers
Mould cavity
Fountain
flow

96. Example of skin formation
Previous colour
New colour
Skin
Real example of skin forming and demos that the material flows threw the centre then out to the sides
Parts produced when production changed from yellow to black colored parts
Yellow material enters cavity first and is pushed out to the surface and forms the skin, the black material follows in behind and forms the core.
Principle applied in some two shot process’s where internal layer is a regrind or second polymer.

97. Molecular orientation
Slow injection speed
Mould cavity
Low orientation/Stiff flow
Thicker frozen layers

98. Molecular orientation
Fast Injection Speed
Mould cavity
High orientation/Easy flow
Thinner frozen layers

99. Slower filling or colder moulds
Residual stress
Slower filling or colder moulds
Thick frozen layers
Mould cavity
High residual stress !

100. Faster filling or hotter moulds
Residual stress
Faster filling or hotter moulds
Thin frozen layers
Mould cavity
Low residual stress !

101. Effect of residual stress
Fast fill rate - Lower internal stress
Slow fill rate - Higher internal stress
Two moulding with different internal stress’s due to the rate of fill of the cavity
Both parts made from same machine in the same material with all conditions the same accept for the injection speed
One injected at 99% speed the other at 10% speed
Both then placed in an oven at 100C for 24 hours – stress is then allowed to relax as the material heats up hence the distortion
Which has the highest stress levels ?
Why ?

102. Injection phase Summary Aim to fill the mould as quickly as possible.
Uniform melt front speed as part fills.
Mould cavities fill evenly.
Ensure mould is 99% full.

103. Aims during the holding phase
Start Mould Safety
Apply Locking Tonnage
Mould
Closes
Open
Period
Injection Speed
& Pressure
Injection
Phase
Mould
Opens
Mould
99% Full
Hold
Pressure
& Time
Holding
Phase
Cooling
Phase
Gate
Freeze-off

104. Polymer compression Pressure is applied to the melt.
Melt density increases.
Material shrinkage reduces.

105. Gate freeze-off 2 4 6 8 10 12 14 16 (gms) Gate frozen Weight
using 55oC mould
& 230oC melt
Gate frozen
using 35oC mould
& 230oC melt
Weight
Holding time (secs)

106. Holding phase Summary Ensure adequate compression of the melt.
Reduce sinks and voids by compensating for the shrinkage of the polymer chains
Obtain consistent component quality by establishing gate freeze-off time.
Obtain correct component weight/dimensions by the application of a suitable pressure.
Rule of thumb:
Amorphous plastics require a low holding pressure.
Semi-crystalline plastics require a high holding
pressure.

107. Aims of the cooling phase
Start Mould Safety
Apply Locking Tonnage
Open
Period
Mould
Closes
Injection Speed
& Pressure
Mould
Opens
Injection
Phase
Mould
99% Full
Screw Back
Completed
Holding
Phase
Hold
Pressure
& Time
Cooling
Phase
Gate
Freeze-off
Start Screw Rotation

108. Factors to consider Polymer type – Semi-crystalline or Amorphous.
HDT – Heat Distortion Temperature.
Capacity of temperature control unit.
Cooling time versus refill time (open nozzle).

109. Cooling rate, shrinkage & distortion
Mould Tool ?
HOT SIDE
COLD SIDE
Which way will the part bend ?

110. Cooling rate, shrinkage & distortion
Residual orientation effect (stress)
Normal shrinkage effect
Hot side
Cold side
Hot side
Cold side
More
shrinkage
Low orientation
High orientation
Aimated to show the two effects
Distortion at the moulding machine
Warpage as part relaxes in service or storage

111. Cooling phase
Summary
To remove heat at an appropriate rate to promote maximum service properties.
To remove the heat from all cavities evenly.
To allow the part to be ejected without distortion.
To provide sufficient time to plasticise a homogeneous mass of molten polymer.

112. Troubleshooting

113. Troubleshooting Is the fault acceptable – check the first off.
ASSESSMENT
Is the fault acceptable – check the first off.
CORRECTION
If not, then check the basics first:
The mould (damage, vents).
The material (grade, batch, moisture).
The machine (wear, malfunction).

114. Slower filling or colder moulds
Residual stress
Slower filling or colder moulds
Thick frozen layers
Mould cavity
High residual stress !

115. Faster filling or hotter moulds
Residual stress
Faster filling or hotter moulds
Thin frozen layers
Mould cavity
Low residual stress !

116. Relationship between faults & cycle steps
OUT OF CYCLE
COOLING
HOLDING
INJECTION
Flash
Short
Gas trap
Jetting
Flow lines
Weld lines
Dieseling
Weight
Sinking
Flash
Voids
Dimensions
Distortion
Contamination
Mica marks
Illustartion to show where faults occur within cycle
Get delegates to say where examples such as flash,weld lines etc. occur then show lists
Note: Some faults can be related to more than one specific part of the injection moulding cycle.

117. Examine the mouldings and determine the:
Troubleshooting
Examine the mouldings and determine the:
Fault
Cause
Remedy
Issue samples – get delegates to consider fault – Cause - Remedy

118. Example of Fault - Cause - Remedy
Burn mark (Dieseling)
Trapped
gas
Clean vents.
Reduce Locking tonnage.
Reduce injection
speeds or profile.
Example to show
Fault – definintion of problem ( Flash – excess material arouond edge of part )
Cause – why flash occurs
Remedy – how to cure, note multiple remedies, need to determine appropiate steps
Reduce melt temperatures.

119. Processing variables Short term Long term Locking tonnage
Holding pressure time
Cooling time
Injection speed
Holding pressure
Change over position
Shot weight
Decompression
Ejector speed
Melt temperature
Mould temperature
(Oil temperature)
Determine actual
temperatures using
a pyrometer for
both mould and melt.
Short term vs long term
Back pressure
Screw speed

120. Systematic approach Eliminate faults in order of priority:
Those that potentially damage the mould
- Flash
- Gas burns/traps
Optimise the filling phase
% full
Order in which problems addressed
Filling phase faults
- Jetting
- Flow lines
- Weld lines

121. Systematic approach Holding phase related - Voids - Sinks - Undersized
Optimise the holding phase
- Holding pressure
- Gate freeze-off time
- Cushion Size
Order in which problems addressed
Optimise the cycle time
- Cooling time

122. Troubleshooting Summary
Adopt a logical and systematic approach
Change one condition at a time
Consider the interaction of conditions
Keep samples
Keep notes
Be patient
Don’t be a knob
Twiddler!!

123. Injection Moulding Technology Processing & Troubleshooting
Part 3
Processing & Troubleshooting

124. Blade ejection
READ

125. Round ejection
READ

126. Sleeve ejection
READ
Return

127. Sprue bush
READ
Return