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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

MuCell® - Positive Impact on

Project

Trexel inc.

contact : Martin Jacobi m.jacobi@trexel.com