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MuCell® Injection Molding create value by Microcellular Foaming
Maxéville, Octobre 2014
Company Trexel
Equipment / Process / Applications
Impact on Part Design / Quality / Economics
HISTORY OF FOAMED POLYMERS
1900 ‘10 ‘20 ‘30 ‘40 ‘50 ‘60 ‘70 ‘80 ‘90 2000 ‘10
First
Foamed
Natural
Rubber Introduction of
Thermoplastics
Chemical
Foaming
Agents
Physical
Foaming
Agents Microcellular
Extrusion
Microcellular
Injection Molding
Structural
Foam
Molding
Focused Research
Microcellular
Foaming
MuCell® INJECTION MOLDING “The most significant plastic processing innovation in the last 20 Years”
MuCell Process developed at Massachusetts
Institute of Technology. (M.I.T.) Exclusively
licensed to Trexel Inc. in mid 90’s.
Trexel over the last 15 years commercialized, industrialized MuCell
Technology. Today, Trexel owns over 50 global patents covering
article and methods in producing microcellular foam. Support leading
OEMs globally from HQ in Boston and through subsidiaries in Japan,
Germany, Hong Kong and China.
Patented, closed loop processing solution
creating predictable and repeatable
homogeneous microcellular material structure
with average cell size <100 microns.
• MuCell is a foaming technology
Putting small cells into a thin wall plastic part
• Primarily using nitrogen as the foaming agent
What is MuCell®
MuCell ® Commercial Applications
Industrial & Electrical Business Equipment Automotive
MuCell® process animation
The MuCell Process
• Benefits of the MuCell process come from two key
process effects:
– Dissolving an SCF (Supercritical Fluid) into a polymer reduces
the material viscosity
• typical range : 10 to 15%
– Cell growth provides final packing of the part
• Reduces cavity pressure
• Equal cavity pressure through the mold cavity
• Cycle time reduction due to shorter pack/hold and increase
mold contact
Plasticizing effect – improved flow
Mould was cooled such that
solid parts were no longer
filling the mould
Material: Valox 420 SEO (PBT GF30)
Solid at 30 °C Tool Temp.
With same parameters and
MuCell® on, the parts could
easily fill
MuCell® at 30 °C Tool Temp.
Material: Valox 420 SEO (PBT GF30)
DSC - Curve: PBT GF 30 with
mould temp. 80°C
DSC - Curve: PBT GF30 with
mould temp. 30°C
Melting temperature : 225,4°C
Heat of Fusion (H): 40,67 J/g
Melting temperature: 225,0°C
Heat of Fusion (H): 41,93 J/g
Without foam 10% physical foam
Crystallinity Level is identical
Microcellular Foam Properties
Cycle Time Reduction
Solid
Molding
Mucell
Start of Injection
Pack &Hold Cooling Injection Motions
6 sec
6 sec
3 sec 4 sec
2.5 sec 0.5 sec
17 sec
15 sec
Typical Cycle Time Reduction: 15-30%
30 sec
24 sec
Clamp Tonnage
10/3/2014
Cavity Pressure
0
50
100
150
200
250
300
0 2 4 6 8 10
Time, sec
Pre
ssu
re, B
ar
M5 Gate
Solid Gate
Tranfer Pointold End of Hold Time
Solid M5
Peak Cavity pressure (bar) 250 25
Clamp Tonnage = Cavity Pressure * Projected surface area
Improved Dimensions
• Typical MuCell process pressure curves
Cavity Pressure
0
10
20
30
40
50
60
70
80
0 2 4 6 8 10
Time, sec
Pre
ss
ure
, B
ar
M5 Vent
M5 Gate
Transfer Point – Injection
to hold
Problem Solving Strategy + Material / Weight Savings 8-12%
+ Reduced # Mold Iterations
+ Additional Tooling options
- Press sizes already determined
- Non-optimal tooling
Designing for Function
+Material / Weight Savings
20-30%
+ Significantly reduced # Mold
Iterations
+ Optimal Gating
+ Optimized Press-sizes
+ Reduced time to production
STRATEGIC IMPLEMENTATION of MuCell®
TECHNOLOGY
Part
Design Tooling
Pre-production
Validation
Production
Release
Volume
Production
Cost-down
Initiatives
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
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!
Filling from “thin to thick“
Wall to rib ratio 1:1 possible
Differences in Wall Thicknesses
Conventional design MuCell® design
Preferred injection
with MuCell® Injection in solid
(with MuCell® still possible
but with limited density reduction)
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: 65 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
Lightweighting Application
Fan Shroud
Fixing Points
Fixing Points
Functional Design
Conventionell:
1,0 mm basis thickness
2,0 mm in selected areas
4 Injection Points
MuCell Part Weight = 670 g
Additional Costs Hotrunner (tool+maschine) = ca. 25.000,- €
But: Material Savings > 80.000,- € per Year
(based on 60.000 parts/y - 2,40 €/kg Material Cost)
MuCell Design:
2,0 mm overall thickness
2 Injection Points
Part weight = 880 g
2,0 mm
1,0 mm
2,0 mm
= Injection Gate
Lightweighting Synergies Between
3M™ Glass Bubbles and MuCell®
MuCell® Equipment T series
• fully integrated or stand aside
• Interface Kit eliminated
• lower energy consumption
• less maintainance
• easy to operate :
indicate shotweight and
%SCF only
MuCell® - on the market
Examples
Trexel inc.
Material:
PA 6 GF15 MN25
MuCell® Benefits:
8 % weight reduction
20 % cycle time reduction
30 % smaller machine size
Fatigue-to-failure improved by 400 %
MuCell® Fan Shroud
Shroud + hinge
combined in one
mould
MuCell® Climatic Control Housing
• Shorter cycle times due to quality improvement
• Clamp force reduction
• Easier to assemble
MuCell® Benefits
Mercedes Benz : Project MFA (B Class …)
Pressure
• weight saving by design + density
• reduced warpage, easy assembly
2 parts out of 11
High Gloss Frame with MuCell®
Screen DVD player
• Clamp Force reduced by 50%
• more design freedom
• reduced warpage
Mercedes Benz – W246
Head Lamp Housing
• 500g weight reduction per part !
IP Carrier Golf VII
MuCell in Packaging
