1. MuCell® Injection Molding
January 26, 2012

2. Outline Fundamentals of MuCell Basic Part Design
Design Optimization for MuCell
Expansion Molding 2

3. What is MuCell® MuCell is a foaming technology
Putting small cells into a thin wall plastic part
Primarily using nitrogen as the foaming agent

4. MuCell Process Basic Steps
Melt plastic prior to SCF (Super Critical Fluid) injection
Inject SCF during screw rotation
Dissolve SCF into the polymer melt (single phase solution)
Inject SCF
Dissolve SCF
Read text. +
SCF
Polymer
Diffusion Complete 4

5. MuCell Process
Once the SCF is dissolved into the molten polymer it must be kept under pressure
In the molding machine this means:
Screw position control
Shutoff Nozzle
In the mold:
Valve gates for hot runner molds
Foaming occurs during injection into the mold
Read text.
Time 5

6. MuCell Equipment

7. The MuCell Process
Dissolving an SCF (Supercritical Fluid) into a polymer reduces the material viscosity
Viscosity changes
10% to 15% for a 30% glass fiber reinforced semi-crystalline engineering resin
15% to 25% for an amorphous resin
Reduced injection pressures at equal conditions of temperature and speed
Improved flow lengths
Cell growth provides final packing of the part
Reduces residual stress patterns by eliminating traditional pack and hold phase
Results in improved part dimensions
Cycle time reduction due to shorter pack/hold and increase mold contact

8. Typical Cycle Time Reduction: 15-30%
Start of Injection
30 sec
3 sec
4 sec
17 sec
6 sec
Solid
Molding
Injection
Pack &Hold
Cooling
Motions
2.0 sec
0.5 sec
14 sec
6 sec
Mucell
22.5 sec
Typical Cycle Time Reduction: 15-30% 8

9. Transfer Point – Injection to hold
Pressure Monitoring
Typical MuCell process pressure curves
Transfer Point – Injection to hold
This is a typical cavity pressure curve for the MuCell process. It can be seen that the cavity pressure near the gate increases rapidly during the fill process (a 1.33 second fill time). Once injection stops, the pressure at the gate drops rapidly to a pressure just slightly higher than the pressure at the end of fill. The pressure at the end of fill is just starting to build at transfer and then builds to a value of about 17 bar before gradually decaying.
This is in contrast to a solid pressure curve as show in this next slide. 9

10. Part Quality Easier to Achieve1 2 3 4 5
Gate
Position
95.9
200
Straightness 10

11. MuCell provides a long term strategic cost advantage for molded parts
Significant manufacturing cost savings
Cycle Reduction (15-30%)
Weight Savings (6-30%)
Reduced Clamp Tonnage (30-60%)
Previously unattainable quality improvements
High dimensional stability
Reduced warpage
Reduced stress in parts
Improved Sound, Vibration Absorbency
Improved Heat Insulation 11

12. Outline Fundamentals of MuCell Basic Part Design
Design Optimization for MuCell
Expansion Molding 12 12

13. STRATEGIC IMPLEMENTATION of MuCell® TECHNOLOGY
Cost Reduction Strategy
+ Material / Weight Savings 6-8%
- Limited tooling changes
- Must use existing presses
- Tools already qualified
- Product at/near end of life
Design Process
Cost-down Initiatives
Designing for Function
Material / Weight Savings 20-30%
Significantly reduced # Mold Iterations
Optimal Gating
Optimized Press-sizes
Reduced time to production
Part Design
Pre-production Validation
Production Release
Volume Production
Tooling
Problem Solving Strategy
+ Material / Weight Savings 8-12%
+ Reduced # Mold Iterations
+ Additional Tooling options
Press sizes already determined
Non-optimal tooling 13

14. Part Design - Wall Thickness
Thickest cross sections/hot spots will control cycle time
Identify and eliminate ALL thick sections
Use the new tools in MoldFlow or Catia 5 to highlight the thick sections before the tool is built.
Removing thick sections not only decrease cycle time but reduces overall part weight as well!
A properly designed part typically runs % faster then solid.
A poorly designed part will run % slower.

15. Part Design - Wall Thickness
Specific wall thicknesses with MuCell:
Properly designed parts can be produced with wall thicknesses down to 0.35 mm.
Ideal wall thicknesses is below 3 mm(below 2 mm for unfilled PP and HDPE)
The MuCell process allows for:
Higher wall thickness deviations on the part
More uniform shrink and less warpage at varying thicknesses
No sink marks

16. Part Design - Wall Thickness
Weight reduction is highly dependent on flow factor
Ratio of Flow Length to Part Thickness
Weight reduction also dependent on
Part Thickness
Material
Gate Location

17. Part Design – Rib Design
Rib thickness is not limited by sink marks
The MuCell process eliminates sink marks
Design ribs for performance and not process
Ribs can be equal to the nominal wall thickness
Draft angle of 1 degree per side
Walls should be free of undercuts
Ribs should have a minimum 0.5 mm radius

18. Part Design - Bosses
Boss should be cored out completely to minimize Postblow
Use special high conductivity materials (BeCu, Amco, etc.)
Connect boss to part with minimum R 0.5 mm
Add ribs at thin bosses
Wall thickness > 0.3 mm
Rib thickness > 80% of nominal wall
Avoids back flow of material and air traps

19. Part Design - Bosses Metal core heats up and causes hot spot
Bad design with huge material concentration
At short cooling times part surface is not strong enough to hold gas pressure and material swells out (postblow)
High conductive material is recommended to dissipate temperature
Mold (core) separation
Improved screw boss design
Alternative design

20. Test Results with PBT GF30
Celanex 2300
Solid,
5% and 10% Weight Reduction
Screw:
Delta PT 50 x 25
Hole Ø 4.0 mm (0.8 x screw Ø)

21. Loss in inner wall due to shrinkage
Part Design – Bosses
Solid
Thread engagement is higher with MuCell due to shrinkage on the inner wall of the boss in solid molding
Loss in inner wall due to shrinkage

22. Thread engagement is primarily in the solid wall
Part Design – Bosses
MuCell
Thread engagement is primarily in the solid wall

23. Part Design - Bosses dh d1 = Major Diameter of Fastner
dh = Hole Ø = 0.8 x d1
dB = Boss Outside Ø = 2 x d1
dC = Counterbore Ø = d mm
dp = Minimum Penetration Depth = 2 x d1
0.3 to 0.4 x d1
dp = 2 X d1
n = w X 0.75
w = Nominal Wall Thickness dh
Hole Diameter Maximum Draft Angle = ½º per side
Counter Bore is Important in Reducing Boss Cracking
Hole ID May Range From 0.72 to 0.88 x d1 Depending on Fastner Design
n = w x 0.75 is Required for Faster Cycle Times
The main dimension is the screw diameter and belonging to the diameter you can calculate all other boss dimensions you need for designing your part.

24. Outline Fundamentals of MuCell Basic Part Design
Design Optimization for MuCell
Expansion Molding 24 24

25. Limitations of Solid Molding
Solid molding is constrained by:
Need to push plastic from gate to end of fill without freezing off
Need to pack the part along the entire flow length…
To reduce shrinkage for dimensional stability
To reduce sink marks and vacuum voids
These processing limitations impose design restrictions that affect the ability to reduce wall thickness
The MuCell Process removes these restrictions! 25

26. Designing for Function
Weight reduction by designing part for function and not process
Wall thickness optimized for performance requirements not for packing requirement
Means thinner nominal wall and higher L/t ratios
Viscosity reduction due to SCF
Pack pressure is applied through foaming
How is this applied
2.5 mm wall at 375 mm flow length (150:1 L/t)
8-10% MuCell density reduction
2.0 mm wall at 375 mm flow length (188:1 L/t)
20% Design reduction plus
6–8% MuCell density reduction.
26-28% Total reduction

27. Differences in Wall Thicknesses
Filling from “thin to thick“
Wall to rib ratio 1:1 possible
Possible (recommended) injection with MuCell®
Injection in solid
(with MuCell® still possible)
Conventional design
MuCell® design

28. Interior Trim Volkswagen Touran
LIGHTWEIGHTING APPLICATION
Interior Trim Volkswagen Touran
Design Drivers:
Energy absorption on impact
No visible sink marks through PVC layer
Deletion of “plug-in-module“
Conventional Design:
Base thickness: 4.4 mm
Plug in module: g
MuCell-Design:
Base thickness: 2.2 mm
Rib thickness: 2.2 mm
Comparison of MuCell Design vs. Conventional Design
Equivalent or better energy absorption
Approx. 40 % reduction in part weight
20 % through wall thickness reduction
14 % through deletion of “plug-in-module“
6 % through density reduction

29. LIGHTWEIGHTING APPLICATION
Fan Shroud BMW
Design Drivers:
Mechanical strength for hubs and stators
Minimal wall thickness for air deflection
- Hub and stators 2 mm
Reduced wall to 1 mm
MuCell-Design:
Hub & stators: 2.0 mm
Air deflection: 1.0 mm
Conventional Design:
Base thickness: 2.0 mm
WEIGHT SAVINGS PER SHROUD: 410 GR / 0.9 LBS. 29

30. LIGHTWEIGHTING APPLICATION
First to Market MuCell® Instrument Panel
2012 MY Ford Escape/Kuga Instrument Panel 30 30

31. 2012 MY Ford Escape/Kuga Instrument Panel
Value Summary
Technology Advantages
1.0 pound in weight savings
15% cycle time reduction
45% clamp tonnage reduction
Consumer Benefits
I/P system weight reduction contributes to improved
vehicle fuel economy
Green – reduced carbon foot print by using less material and energy to produce parts
Cost saving approximately $3 per vehicle 31 31

32. Outline Fundamentals of MuCell Basic Part Design
Design Optimization for MuCell
Expansion Molding 32 32

33. Unique Foaming Solutions
Injection/Expansion Molding using the MuCell process

34. INJECTION EXPANSION MOLDING
Combining the MuCell process with a secondary expansion process
Fill mold cavity close to solid weight with SCF laden polymer
Increase mold cavity volume to allow for uniform expansion
6 mm

35. INJECTION EXPANSION MOLDING

36. INJECTION EXPANSION MOLDING
Expansion applications targets
Door Carriers
Load Floors
Under Body Shields
Engine Covers
Flexible Soft Foams
IP’s (Dolphin)
Floats

37. IINJECTION EXPANSION MOLDING
The MuCell process allows for expansion ratios up to 4X
Double what is achievable with other foaming technologies
The high expansion ratios provide unique part performance
Superb weight to stiffness ratios when using LGF materials
Stiffness is proportional to thickness cubed
Most standard plastic part design options can be used
Dog houses, Screw bosses, Ribs
Openings
Limitations
Expansion only in direction of mold or core movement
Corners are not sharp
Requires special tools

38. Summary The MuCell process incorporates small amounts of
physical foaming agent into the polymer melt to create
a microcellular foam structure
Reduction in material viscosity
Gas expansion replaces the function of the pack/hold
phase
Reduced residual stress results in improved dimensions
Improved contact with the mold surface shortens cooling
This leads to part design for function not process
Flow can be from thin to thick
Wall thickness variations are more easily tolerated
Larger part weight reduction then can be achieved from MuCell
foaming alone
The MuCell process can be combined with other processes to
achieve very unique part and cost structures