TPV Seal Geometry Effects on Compression Set (CSet) and Compression Load Defglection -...

7/30/2019 TPV Seal Geometry Effects on Compression Set (CSet) and Compression Load Defglection - Above-The-belt 2006

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TPV Seal Geometry Effects On

Compression Set (CSet) andCompression Load Deflection (CLD)

Jere Anderson, Trexel, Inc

Felix Zacarias, Santoprene Specialty Products

ExxonMobil Chemical

Above-The-Belt 2006 Novi, MI


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Outline Background

Study objectives

Approach

Sample production

Materials

Process Results

Conclusions

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Background Primary and secondary automotive weatherseals are

complex, multifunctional profiles that:

Control or affect:

Water ingression

Wind noise

Door closing effort

Aesthetics at vehicle entry

Typically consist of:

Sponge sealing section

Mounting section

Dense polymer

Metal reinforcement

Trim

Secondary lip

Skin coat

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Background Performance requirements for weatherseal sponge

Surface contact area for sealing

Conform to sealing surface imperfections and build tolerances Low compression force

Withstand high deformations

Provide rapid, elastic deformation recovery

Operate over a wide temperature range Maintain properties with cyclical deformations

Provide consistent properties over long product life

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Background

Meeting weatherseal performance needs requires:

Materials

Process Part Design Trexel MuCell process

Closed cellular structure

Designed for performance Foamability

Surface aspect

Low CLD

Low CSet

Elongation

Geometry

Dimensions Sponge specific gravity

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Background EPDM material properties TPV material properties

Current weatherseal designs based on EPDM properties

Historical material of choice Seal designer and manufacturer experiences

Different design rules anticipated for optimal seal performance with TPV

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Objective The objective of this investigation was to quantify the

effects of varying TPV profile design on key weatherseal

performance criteria to define TPV sponge designs for

optimal weatherseal performance.

Study variables

Profile shape

Profile wall thickness Sponge density

Measured results

CSet

Short term

Long term

CLD

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Approach Produce D shaped profiles of equal height varying:

Shape

Wall thickness 1.5 and 2.0 mm

Sponge density 0.55 to 0.65 gm/cc

Assess performance differences

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Sample Preparation Process

MuCell foam extrusion process

Physical foaming technology Direct injection of supercritical N2 or CO2

Equipment

Trexel extrusion system 63 mm diameter, 32:1 L/D

Throughput 45 kg/hr (100 lb/hr)

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Sample Preparation Materials

Santoprene X121-60F150 polymer

typ. properties test method Specific gravity 0.97 g/cc TPE-0105/1

Hardness 60 Shore A TPE-0104

Ultimate tensile str. 4.5 MPa (650 psi) TPE-0153

Elongation @ break 390% TPE-0153

SCF

Type N2

Delivery pressure 172 bar (2,500 psi)

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Results Samples Produced

Actual optical comparator tracings

-2O Profile 22O Profile 57O Profile

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Results11

Short Term Cset - 22hr @ 70OCSantoprene

TMX121-60F150, Spong e S.g. 0.54 - 0.60 g/cc , Test Me tho d TPE 0016

20.0

25.0

30.0

35.0

40.0

45.0

50.0

1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5

Wall Thicknes s (m m )

CSet

(%)

-2O

Profile

22O Profile

57O

Profile


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Results12

CLD - 50% and 25% Com pressionSantoprene

TMX121-60F150, Spon ge S.g. 0.54 - 0.60 g/cc, Tes t Met ho d A STM D 1667

0

2

4

6

8

10

12

14

16

18

20

22

24

26

28

30

32

34

36

1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5

Wall Thickness (mm )

CLD

(N/1

00mm)

-2O

Pro file - 50%

22O

Pro file - 50%

57O

Pro file - 50%

-2O

Pro file - 25%

22O

Prof ile - 25%

57O

Pro file - 25%


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Results13

50% Com pressio n CLD vs. Short Term CSetSantoprene

TMX121-60F150, Sponge S.g. 0.54 - 0.60 g/cc, Tes t Me tho ds ASTM D 1667 & TPE 0016

0

5

10

15

20

25

30

35

40

1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5

Wall Thickness (m m )

CLD

(N/10

0mm)

10

15

20

25

30

35

40

45

50

CSet(%)

-2O

Profile

22O

Profile

57O Profile

-2O Profile

22O

Profile

57O

Profile CSet

CL D


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Results14

Lo ng Term Cset - 1,000 ho urs @ 70OCSantoprene

TMX121-60F150, Spong e S.g. 0.54 - 0.60 g/cc , Test Metho d TPE 0016

0

10

20

30

40

50

60

70

0 100 200 300 400 500 600 700 800 900 1000

Time (hours)

CSet(%

)

Typical EPDM

Typical 60F150

-2O

Profile

57O

Profile


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Results SummarySantoprene X121-60F150 Sponge 0.54 0.60 g/cc

Anticipated CLD and CSet range:

Min. Max. Units

CLD (25% compression) 2.6 10.8 N/100 mmCLD (50% compression) 7.0 34.5 N/100 mm

CSet 32 48 %

Shape and wall thickness changes from 1.4 to 2.2 mm.

Sponge density changes did not affect CSet or CLD.

Short term CSet is reduced with:

Shape change parallel to load 5% points at fixed wall thickness.

Wall thickness increase 1.4% points/0.1 mm increase.

A total of 16% points with both shape and wall thickness changes.

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Results SummarySantoprene X121-60F150 Sponge 0.54 0.60 g/cc

CLD is reduced with :

Shape change to more round profiles at fixed wall thickness

11 to 12 N/100 mm (50% compression)

1.7 to 3.8 N/100 mm (25% compression)

Decreased wall thickness

2 N/100 mm for a 0.1 mm wall thickness reduction

(50% compression)

1.7 N/100 mm for 0.1 mm wall thickness reduction

(25% compression)

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Conclusions Profile shape has a large effect on TPV sponge CSet

and CLD.

Profile shape for TPV can be optimised for CSet and

CLD independently of sponge specific gravity.

TPV CSet is consistent over time

TPV sponge CSet EPDM sponge CSet after 700

hours (29 days).

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THANK YOU

FOR YOUR ATTENTION!

The authors would like to thank Curt Waddle from

ExxonMobil Chemical for profile testing support.

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TPV Seal Geometry Effects on Compression Set (CSet) and Compression Load Defglection -...

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