Solving Polymer Processing Problems with

Computer SimulationJohn Perdikoulias

Compuplast Canada Inc.IPR 20

07

Objectives• Demonstrate the application of

CAE/CFD/Simulation in polymer processing

• Show how simulation can be used to troubleshoot/optimize a process/design

• Explain certain observations or phenomena with the aid of simulationIP

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Problem: Particles/Gels in Film Sample

• In this system, periodic “showers” of gels or particles were observed in the film sample.

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Film/Sheet Extrusion

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Single Screw ExtruderConventional screw

Hopper

Feeding zoneCompression zone

Mixing element

Metering zone

IPR 20

07

Comprehensive Tests with the Macro Glass Window Extruder

Song, Perdikoulias and Planeta, ANTEC 2000

IPR 20

07

Photo of Extruder Screw

• The screw used to produce the film had a noticeable discoloration in the feed and compression region.

IPR 20

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Comprehensive Tests with the Glass Window Extruder

LDPE 50 RPM @ W2 & W3, melt @ ~ 17DIP

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Solid Bed Break-Up

• Improper screw design results in solid bed break-up and there is no mixer to compensate

IPR 20

07

Define: Solid Bed Ratio

• Ratio of Solid bed width to Channel Width

• Indication of melting capability of the screw

Solid Bed

Channel Width

Melt Pool

Flow Direction

SB Width

Channel WidthSolid Bed

Ratio =IP

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Compuplast®

Virtual Extrusion Laboratory™Extruder Simulation

IPR 20

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Analysis of Solid Bed Ratio

Simulation indicates that the Solid bed ratio does not reduce gradually as preferred but actually increases near center of screw.

IPR 20

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Good melting

Solution: Modify Process Conditions, Change Material or Screw Design to achieve better melting performance

IPR 20

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Problem: Polymer Degradation

• Screen Changer

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SCREW / BARREL / SCREENCHANGERDegradation

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Original ShapeShear stresses inside the flow domain

Compuplast® Virtual ExtrusionLaboratory™, 2D FEM module

IPR 20

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New ShapeShear stresses inside the flow domain

Compuplast® Virtual ExtrusionLaboratory™, 2D FEM module

IPR 20

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SCREW / BARREL / SCREENCHANGER(Improved design)

Degradation on

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Polymer Degradation Solution

• Ensure adequate shear stress in all flow channels.

– Proper Channel Design– Proper Operation ConditionsIP

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Problem: Periodic Lines in Tubular Film Bubble

• Lines appear as a visual defect in film produced on a spiral mandrel type die.

IPR 20

07

Spiral Mandrel Dies

• Commonly used for tubular (blown) film production since 1950’s.

• In more recent years applied to pipe and blow molding diesIP

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Spiral Mandrel Flow Video

IPR 20

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3D FEM - Pressure Drop

IPR 20

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3D FEM - Shear Stress

Low Shear StressIP

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3D Flow Analysis

• Velocity contours for 2/3 of the die and path line seed locations

Particle Path Line SeedsIPR 20

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3D FEM Spiral Die Simulation

Weld LineIP

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Objective of Profile Extrusion• Maximize Profits• Maximize Production Rate• Minimize Design Time• Minimize Development Time

Make This Not This

IPR 20

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Example

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B-SIM,Blow Molding Simulation Software

Accuform, Czech Republic

IPR 20

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Extrusion Blow MoldingFuel Tank

IPR 20

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Stretch Blow Molding(Bottle)

IPR 20

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Stretch Blow Molding

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Extrusion Blow Molding Optimization - Example 1

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Extrusion Blow Molding Optimization - Example 1

• Automatic optimization of the parisonthickness profile:

] t / )t-(t C - [1 t t finalfinalfinal einit ei

init e1i =+ IP

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Extrusion Blow Molding Optimization - Example 1

• Automatic optimization results - the final thickness distributions:

0

0.2

0.4

0.6

0.8

1

1.2

0 20 40 60 80 100 120 140 160

Arc length (mm)

Thic

knes

s (m

m)

StartStep 3Step 6Step 9

A BIP

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0

0.2

0.4

0.6

0.8

1

1.2

0 10 20 30 40 50 60

Arc length (mm)

Thic

knes

s(m

m)

StartStep 3Step 6Step 9

Extrusion Blow Molding Optimization - Example 1

• Automatic optimization results - the final thickness distributions:

A BIP

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

1.6

0 20 40 60 80 100 120

Arc length (mm)

Thic

knes

s (m

m)

OriginalOptimized

Extrusion Blow Molding Optimization - Example 1

• Original and optimized initial thickness profile of the parison:

A BIP

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0

0.2

0.4

0.6

0.8

1

1.2

1.4

0 5 10 15 20 25 30 35 40 45

Arc length (mm)

Thic

knes

s (m

m)

OriginalOptimized

Extrusion Blow Molding Optimization - Example 1

• Original and optimized initial thickness profile of the parison:

A BIP

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Parison Design Comparison

38 mm Not-profiled 50 mm Profiled

IPR 20

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T-SIM,Thermoforming Simulation Software

Accuform, Czech Republic

IPR 20

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Thermoforming Process

• Characterized by large deformations of polymeric materials

Deformationfield visualizedby an initially square gridIP

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Positive forming

IPR 20

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Negative forming with undercuts

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Effect of temperature distribution

Uniform initial temperature (160°C) Final thickness profileIP

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Effect of temperature distribution

Optimized initial temperatureprofile (152 - 162°C)

Final thickness profileIP

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Webs or Wrinkles

• T-SIM used as a web prediction tool

Courtesy of Vyvaplast s.r.o, Czech Republic

IPR 20

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Case study II

• Simulation in T-SIM predicts several webs (wrinkles)

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Comparison

• Comparison with a real product shows a very good agreement

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Comparison of thickness distribution for two different plugs

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Comparison of thickness distribution for two different plugs

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Image Distortion

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Prediction of image deformation

Preprinted flat sheet

Deformedsheet withimage

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Reverse engineering of image deformation

Image onfinal product

Pre-distortedimage,predictedby T-SIMIP

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Moldex3D/SolidInnovative True 3D Simulation for

Plastics Injection Molding

CoCoreTech System Co., Ltd.reTech System Co., Ltd.http://www.Moldex3D.com

IPR 20

07

Why 3D Analysis ?• Realistic simulation with minimum model

simplification.

3D Solid model3D Solid model Automatic solid meshAutomatic solid mesh AnalysisAnalysisIPR 20

07

Upper Phone Cover

IPR 20

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Moldex3D Flow/Filling

IPR 20

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Moldex3D-Flow: Cover Part

IPR 20

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Moldex3D-Warp:Cover Part

IPR 20

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Application: WrenchMoldex3D/Solid-I2ABAQUS

IPR 20

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Model Summary• Introduction

– Thickness�3.1 ~ 12.3 mm– Length�227.7 mm– Width�49 mm

• Material– PA66 \ ORGALLOY

RS6630 \ ATO ( 30%GF )

• Process Condition– Filling Time�1.5 Sec– Melt Temperature�300 �– Mold Temperature�70 �

• Injection Analysis Results– Filling

• Melt Front• Temperature Distribution

– Warpage• X-Displacement• Y-Displacement• Z-Displacement

• Structure Analysis results– Stress– Strain– DisplacementIP

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A_A section3.1mm

5.77mm

Injection Simulation: Mesh Model

Elem. No. = 8,477Node No. = 13,340

A

A

49mm

227.7mm

IPR 20

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Injection Simulation: Melt Front

IPR 20

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Injection Simulation: Temperature

IPR 20

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Injection Simulation: Fiber OrientationFiber Orientation is

the fiber orientation vector distribution of plastic melt at EOF.

1/3 means the fibers exhibit an random orientation; 1 means the fibers are 100% oriented. The higher value means the fiber is highly oriented over the region by the flow field.

Fiber orientation effects not only the shrinkage rate but also the strength of the part.

IPR 20

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Injection Simulation: Warpage

X-Displacement

Y-DisplacementTotal Displacement

IPR 20

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Structure analysis: Link to Abaqus

• Model preview • Pre-process

– Load– Constraint– Others

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Structure analysis: Boundary Condition

Fixed support

Force = 30 NIPR 20

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Structure analysis: Deformation

X 5 X 5

Fiber-filled molded part has small deformation

Anisotropic (With Fiber Orientation) Isotropic (Without Fiber Orientation)

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Concluding Remarks• Process simulation provides more

information for correlation between process conditions and production problems

• Simulation gives new insight into problems, which can lead to faster and more precise solutions

• Simulation offers the possibility for precise process/design optimization

IPR 20

07

THANK YOU!!!

Questions?John Perdikoulias

www.COMPUPLAST.netjp@compuplast.netIP

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