2012
Moldex3D R11
European
Webinar
Series
Application and Process Optimization
Technology for Plastic Injection Compression
Molding(ICM)
1
Dr. Enoch Chen
»Current position:
CoreTech System Technical Research Division
» Education:
PhD in Mechanical Engineering at University of Florida
» Specialization:
Experimental mechanics /Residual strain analysis in
composite
Research assistant in “Experimental Stress Analysis Laboratory” at University of
Florida, specialize in the optical measurement of process-induced residual strains in
composites and finite element analysis.
Research assistant in “Advanced Material Characterization Laboratory” at
University of Florida, specialize in, focus on shrinkage property study on concretes
applying the optical method.
In recent years, engage in plastic injection molding analysis and the solutions to
molding problems. In addition, research on many special molding processes,
including injection compression molding, gas-assisted injection molding, hot runner,
and optical application. Moreover, experience with integration of injection molding and
structural analyses in PLM.
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Content
>
>
>
>
Why we use ICM?
What are the Issues when using ICM?
What Moldex3D can help?
How we use CAE to solve issues in practical case?
- CIM versus ICM on light guide plate
- Warpage issue for DVD disks in injection compression molding
- Residual stress issue for optical lens in injection compression
molding
> What we can conclude?
> Q and A
3
Why we use ICM?
4
Overview of CIM
Steady Process Operation
Easy Process Automation
Conventional Injection Molding
(CIM)
High Productivity
Complicated Geometrical
Construction
5
Overview of CIM
Filling
Packing
Non-uniform
packing effect
Cooling
Mold open
/Ejection
Problems
Non-uniform
shrinkage
Severe Warpage
Cavity
pressure
Sink Mark
Residual Stress
/Birefringence
6
Problems in Optical Parts Using CIM
> DVD disk warpage issue
> Optical lens residual stress issue
> Light guide plate issues
Ref: http://www.cmo.com.tw
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New Mechanism Needed
> Packing and holding is always need to compensate the
shrinkage
Cavity pressure
> But
– Under packing occurs if high packing pressure is required
– Over packing sometimes occurs , and may cause extra
residual stress and molecular orientation
– How to pack melt into cavity through a frozen gate?
> New compression mechanism appear
8
Introduction to ICM
> As early as to 1960s , Japanese injection molding
masters began to research on ICM. However, it was not
well developed due to the limitations of machines and
molds.
> In the 1980, injection machine and mold technology had
a very fast development which is very good for injection
compression development.
> Nowadays, it has become one of precision injection
molding processes. The advances in CAE also help the
feasibility of this special molding process.
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Introduction to ICM
Compression molding
Injection molding
Injection Compression Molding
(ICM)
Melt is compressed by the movable
mold to complete the filling during
the compression phase
Uniform packing
Cavity pressure
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ICM Process Cycle
Close mould down to the compression gap
Sequential or simultaneous compression
by clamping the mould
Inject and fill cavity 80 – 95%
(equivalent to 100% or more of the ultimate
volume)
Apply hold pressure, cool,
open mold, and eject part
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Types of ICM
Short-shot
compression
Full-shot compression
Co-injection
compression
12
Benefits of ICM for Parts
Reduced
Sink mark and
warpage
Increase
Dimension
Accuracy
Reduced
molecule
orientation
Less
material
shear
Advantages
Reduced
Residual
stress
Reduced
birefringence
13
Benefits of ICM for process
Reduced
cycle time
Reduced
Injection
Pressure
Advantages
Improved
venting
Reduced
Clamping force
14
ICM Applications
> Application Fields
- In-Mold decoration parts
- Optical parts
- Finely textured surfaces
15
ICM Applications
> Application Fields
- Automobile parts
- 3C products (PDA cover, cell phone cover, Notebook
cover etc.)
- Others(Fuel cell bipolar plate, SD card etc.)
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What issues we have when using
ICM?
17
Issues of ICM
Extra costs for the
machine and mould
Flash
Problem
Disadvantages
Parts with great depth
in the injection direction
are not suitable for ICM
Complicated
process condition
control
compression time, compression force,
compression speed, and compression
distance
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Issues for ICM
> Issues from CIM to ICM
– Very complicated process parameter control,
– Smaller process window,
– The injection pressure, temperature, clamping force and their
histories become very different,
– The physical mechanism and the detailed internal information
cannot be fully understood by the experiments,
– Different materials have different viscosity, compressibility etc.
It is a much more complicated process
A scientific tool is in great demand: CAE
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What Moldex3D can help?
20
Numerical Theory-Basic Governing
Equation
> Full 3D theory
> Mass Conservation
∂ρ
+ ∇ ⋅ ( ρv ) = 0
∂t
> Momentum Conservation
∂
(ρu ) + ∇ ⋅ (ρuu − τ ) = −∇p + ρg
∂t
> Energy Conservation
> Moving Grid Approach
21
Numerical Theory-Constitutive
Equations
> Generalized Newtonian Fluid
–
Modified-Cross model
τ = η (T , γ& )(∇u + ∇uT )
η (T , γ& ) =
(
η o (T )
1 + η oγ& τ
)
* 1− n
 Tb 

T
 
η o (T ) = BExp
> Viscoelastic fluid
–
Constitutive equation (ex White Metzner Model)
 ∂τ

+ V ⋅ ∇τ − ∇V T ⋅τ − τ ⋅ ∇V  = η (∇V + ∇V T )
 ∂t

τ + λ
Add elastic characteristic term
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Compression Surface Setting in
Moldex3D-Mesh
Compression region setting in Moldex3D-Mesh
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Process Parameter Setting in Moldex3DProject
Process settings in Moldex3D-Project
Nozzle can be shut off
before the beginning of
compression
24
24
ICM Analysis in Moldex3D-Project
Mesh Deformation to
generate a gap before
filling
Compression ratio and
compression force
information during
compression
25
ICM Analysis in Moldex3D-Project
Filling completes prior
to compression finish
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Injection Compression Simulation
- Key points and features
> The compression gap, compression speed, delay time
and other settings for ICM are all available in process
wizard.
> Support injection and compression processing at the
same time
> Support new meshing method: compression gap solid
mesh
> Support animation of compression action on melt
> Support to calculate flow residual stress and thermallyinduced stress.
> Support connection with optical analysis.
> Support multiple-component parts.
> Support multiple-time output.
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How we use CAE to solve issues
in practical case?
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Case Study (1): light guide plate
Two different geometry designs and their effects on process and product quality
29
Two Type LGP Model
> Wedge LGP
– 176mm × 99mm rectangular with wedge-shape, which the
thickness varies from 1.5mm at one end to 0.5mm at the
other end
> Flat LGP
– 176mm × 99mm rectangular with constant thickness 1.0mm
SN SN
SN
SN
SN
6
1 mm10 9 8 7
1 mm
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Material and Process Condition
Information
31
Flat LGP with CIM
> During the packing stage of CIM, the pressure decreases
smoothly as packing starts
32
Wedge LGP with CIM
>
During the packing stage of CIM, the pressure decreases
smoothly as packing starts
33
Wedge LGP with ICM
Gate is shut-off
movable mold starts to compress
34
Flat LGP with ICM
Gate is shut-off
movable mold starts to compress
35
Wedge LGP
>
ICM (46~55 MPa) process has more uniform pressure
distribution than CIM (35~71 MPa)
Conventional injection molding (CIM)
Injection compression molding (ICM)
36
Flat LGP
>
ICM (48~50 MPa) process has more uniform pressure
distribution than CIM (12~53 MPa)
Conventional injection molding (CIM)
Injection compression molding (ICM)
37
Wedge LGP - Part Shrinkage
> ICM (-2.3 ~ -0.5 %) has smaller shrinkage variation than
CIM (-3.4 ~ -0.3 %) (more uniform pressure distribution)
Conventional injection molding (CIM)
Injection compression molding (ICM)
38
Flat LGP - Part Shrinkage
> ICM (-2.0 ~ -1.6 %) has smaller shrinkage variation than
CIM (-2.1 ~ 0.9 %) (more uniform pressure distribution)
Conventional injection molding (CIM)
Injection compression molding (ICM)
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Case Study (2): DVD Disk
Compression force profile design for warpage issue
40
Process Conditions Design
Experimental Process Conditions
Melt temperature (oC)
295
Core side (oC)
109
Cavity side (oC)
117
Filling Time (sec)
0.1
Compression Time (sec)
4.19
Cycle time (sec)
4.29
Compression gap (mm)
0.3
Compression force control
Delay time, switch time, compression
force magnitude
41
Design Compression Force Profile
> Compression force profile
2. Delay time
1. Force
magnitude
3. Switch time
42
Numerical Model Information
>
>
Elements were constructed by hexahedron and average
12 layers in thickness direction.
Cooling Channel are designed in six circles.
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Analysis Results
C1
Parameters
1st
2nd
3rd
4th
Compression
force (tonne)
0
21
9
10
44
Experimental & Analysis Result: Group A
Parameters
1st
A1
Switch time
(sec)
0.08
A2
Switch time
(sec)
A3
Switch time
(sec)
0.08
0.08
2nd
0.05
0.08
0.11
0.08
0.08
3rd
4th
0.02
0.02
0.02
0.05
0.08
0.02
0.02
0.02
0.05
0.08
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Experimental & Analysis Result: Group B
Parameters
1st
2nd
3rd
4th
B1
Delay time
(sec)
0.1
0.1
0.3
0.7
3.27
3.07
B2
Delay time
(sec)
0.1
0.4
0.7
1
3.57
3.27
2.97
0.1
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Experimental & Analysis Result: Group C
Parameters
1st
2nd
3rd
4th
C1
Compression
force (tonne)
0.3
19
21
9
10
C2
Compression
force (tonne)
21
7
9
11
10
C3
Compression
force (tonne)
9
8
10
12
0.3
0.3
21
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Case Study (3): Plastic Optical Lens
ICM compression parameter optimization for Residual Stress Issue
48
CIM Experimental Results
Part1
Parts from real mold trials
Part2
CIM Experimental Fringe Patterns
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Numerical Simulation Information
-Meshed Model
Meshed Model
30mm
1mm
2.12mm
Mesh Type
Mixed (Prism and Hexa)
Part dimension
30.00 x 2.12 x 94.00 (mm)
Mold dimension
180.00 x 108.75 x 180.00 (mm)
Cavity(Part) volume
1.9521 (cc)
Cold runner volume
1.86602 (cc)
Element number
158720
Part elements
158720
Node number
92829
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Numerical Simulation Information-Cooling
Channel and Compression Surface
Cooling channel design
Compression region
51
Numerical Simulation InformationMaterial
Viscosity
PVT
Heat Capacity
Thermal Conductivity
52
CIM Numerical Simulation Information
- Process Parameter
Process Parameters Settings
Filling Time
1.9730 (sec)
Melt Temperature
300.0 (ﾟC)
Mold Temperature
90.0 (ﾟC)
Max. Injection Pressure
220.00 (MPa)
Injection Volume (including runner)
3.81812 (cc)
VP Switch by volume(%) filled
98.00 (%)
Packing Time
Packing Pressure
Cooling Time
5 (sec)
Refer to the end of filling pressure
40.0 (sec)
Mold Opening Time
5.00 (sec)
Ejection temperature
Coolant (oil)
Air Temperature
144.0 (ﾟC)
90.0 (。C)
25.0 (。C)
53
CIM Experimental and Simulation
Results
Flow-induced
Fringe Pattern
Thermal-induced
Fringe Pattern
CIM Total Fringe Pattern &
Fringe Order
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Numerical Simulation Information
- Process Parameter
Process Parameters Settings
Filling Time
1.9730 (sec)
Melt Temperature
300.0 (ﾟC)
Mold Temperature
90.0 (ﾟC)
Injection Pressure
220.00 (MPa)
Injection Volume
3.81812 (cc)
VP Switch by volume(%) filled
98.00 (%)
Compression gap
Variable
Delay time
0s
Compression time
5s
Start compressed by Filling stage
Variable (Change with
compression gap)
compression velocity
Variable
Maximum compression force
1500 (tf)
Nozzle is Shut off
Cooling Time
Coolant (oil)
Yes
40.0 (sec)
90.0 (。C)
Mold Opening Time
5.00 (sec)
Ejection temperature
144.0 (ﾟC)
55
Simulation Results
Compression gap=0.5mm, compression
speed=1mm/s, Compression time=5s
56
ICM Simulating and Experimental
Results: Compression Gap Effect
0.1mm (5mm/s)
0.5mm (5mm/s)
1mm (5mm/s)
57
ICM Simulating and Experimental
Results: Compression Speed Effect
2mm/s (0.5mm)
5mm/s (0.5mm)
10mm/s (0.5mm)
58
Simulation Results:
Compression Gap Effect
59
Simulation Results:
Compression Speed Effect
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What we can conclude?
61
Conclusions
> We have introduced Injection compression and its current
industrial applications.
> We have pointed out the issues in design and development for
injection compression products.
> We have proposed a useful tool: An innovative 3D injection
compression simulation technology-Moldex3D.
> We have learned the benefits from using Moldex3D on practical
studies.
> Moldex3D can help us to reduce real mold trials and product
development time to save money and time.
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If you need help or have questions,
please type into the chat box.
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Contact Information
Dr. Chen
enochchen@moldex3d.com
Vincent
vincenthung@moldex3d.com
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Next Webinar
Topic
In-depth Study of Hot Runner Technology and Industrial
Applications
Goals
•Hot runner system and its current industrial applications
•The issues in design and development of hot runner system
•The bottlenecks for traditional product development cycle
•The breakthrough with CAE in hot runner system development
•An advanced hot runner analysis technology and application
•The benefits to practical cases from using advanced hot runner CAE
Time
9:00AM UTC -19 January,2012
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