Current Advances in Low Density SMC for Automotive Class A … · 2016. 10. 28. · −Better if...

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Outline

• Class A 1.2 SPG Low Density

• Development of Current Low Density Class A SMC

• Accomplishments of Current Low Density Class A SMC

• Properties of Low Density Class A SMC

• Current Usage

• Next Steps

• High Strength Structural and Class A 1.2 SPG LD

• Future Developmental Work

• Summary


Development of Current Low Density Class A SMC

• Low Density SMC mostly used in non-appearance applications • Heat shields

• Body panel supports; etc.

• New Low Density Class A Body Panels • Requirement is for a 1.2 specific gravity or lower

• Surface aesthetics comparable to standard density (1.9 SPG) Class A SMC

• Physical Properties − Must meet current low density SMC specifications

− Better if they could meet the standard density SMC specifications

Achieving both required mechanical properties and Class A surface aesthetics has

been a challenge.

Now low density systems of 1.2 specific gravity offer comparable performance in

both respects to standard density (1.9) Class A systems at up to a 46% weight

savings vs steel.


Development of Current Low Density Class A SMC

•Demand for Better Fuel Efficiency

• Improvement of mileage

• Lower carbon emissions

•Competitive Materials

• High Strength Steel

• At the point of diminishing returns in terms of weight reduction

•Aluminum • Requires major re-tooling of the forming & assembly processes

•Carbon Fiber • High raw material cost and limited carbon fiber availability


Accomplishments of Current Class A 1.2 Low Density


Surface Properties: Low Density Class A

Description Loria Index O P DOI

Typical Structural LD

104 6.4 70

Standard Density Class A

1.9 SPG 87 9.3 94

Current Class A Low

Density 1.2 SPG 50 9.6 97


Mechanical Properties

0

10

20

30

40

50

60

70

80

Minimum SpecificationTypical Structural LD

Current LD

Ford LD Specification WSS-M3D188-A: Tensile Strength (MPa)



6

6.2

6.4

6.6

6.8

7

7.2

7.4

7.6

7.8

8

8.2

Minimum Specification

Typical Structural LDCurrent LD

Ford LD Specification WSS-M3D188-A: Tensile Modulus (GPa)



0

0.2

0.4

0.6

0.8

1

1.2

1.4

MinimumSpecification Typical Structural

LD Current LD

Ford LD Specification WSS-M3D188-A:

Tensile Elongation (%)



0

20

40

60

80

100

120

140

160

180



Ford LD Specification WSS-M3D188-A:

Flexural Strength (MPa)



0

1

2

3

4

5

6

7

8



Ford LD Specification WSS-M3D188-A: Flexural Modulus (MPa)


Other Properties

Ford Structural Low Density Typical Structural Current 1.2 Class A

WSS-M3D188-A LD LD

Specific Gravity (1.0 – 1.4)

(ISO 1183, Method A) 1.19 1.19

Water Absorption (max 1.3%)

no blisters 1.14 0.58

Glass Fiber Content (33 – 45%)

by weight 38 38


Current Usage of Class A Low Density SMC

• The material containing the AOC Class A, Low Density resin system is currently in production on the GM C7 Corvette and has been so for over a year. • It has now been approved at two other OEMS. • This Low Density Class A SMC is targeted for a new production application with a major OEM next year.


Next Steps

• Explore the boundaries of the current 1.2 SPG system.

• Lower specific gravity versions • Higher Strength versions.

• Progress on lower density class A and higher strength Class A and structural versions has shown promise.


High Strength Structural and Class A 1.2 Low Density

• A series of modifications to the 1.2 specific gravity materials has yielded:

•Higher strength structural SMC

•Higher Strength Class A materials targeted for 1.25 specific gravity.

• A key point to keep in mind is the concern for the loss of tensile modulus during high temperature painting.

• Even though tensile modulus is important at room temperature, it is more important through high temperature painting cycles.


Higher Strength Structural Low Density

0.0

20.0

40.0

60.0

80.0

100.0

120.0

25 120 175

MP

a

Temperature ºC

Tensile Strength

Current LD

Std. Structural

Structural LD



0.0

2.0

4.0

6.0

8.0

10.0

12.0

25 120 175

GP

a

Temperature ºC

Tensile Modulus

Current LD

Std. Structural

Structural LD



0.0

50.0

100.0

150.0

200.0

250.0

25 120 175

MP

a

Temperature ºC

Flex Strength

Current LD

Std. Structural

Structural LD



0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

25 120 175

GP

a

Temperature C

Flex Modulus

Current LD

Std. Structural

Structural LD


Surface Properties: Higher Strength LD Class A

Description Loria Index O P DOI

Typical Structural LD 104 6.4 70

Standard Density Class A 87 9.3 94

Higher Strength Class A

Low Density 1.25 56 9.3 94


Mechanical Properties Higher Strength LD Class A

Ford Low Density WSS-M3D188-A High Strength Class A LD

Tensile Strength at Break, min 42 MPa 92.2

Tensile Modulus at Break, min 6.8 GPa 9.4

Tensile Elongation, min 0.8% 1.3

Flexural Modulus, min 5.2 GPa 9.9

Flexural Strength, min 115 MPa 198.9

Specific Gravity (1.0 – 1.4) 1.28

Water Absorption, max 1.3%

no blisters 0.6


by weight 47.7


Future Development Work

• Ultra Low Density Class A

• Lower than 1.2 Class A specific gravity

1.0-1.1 specific gravity

0.9-1.0 specific gravity


Ultra Low Density Class A: Surface Characteristics

Description

Loria Index

O P DOI

Below 1.0 SPG

68 9.4 94

1.0 to 1.1 SPG 86 7.8 82

Typical Standard Density

87 9.3 94


Mechanical Properties: Ultra Low Density Class A

Ford Low Density WSS-M3D188-A Below 1.0 1.0 – 1.1

Tensile Strength at Break, min 42 MPa 49.8 60.5

Tensile Modulus at Break, min 6.8 GPa 5.48 6.31

Tensile Elongation, min 0.8% 1.24 1.43

Flexural Modulus, min 5.2 GPa 5.2 6.48

Flexural Strength, min 115 MPa 118 139

Specific Gravity (1.0 – 1.4) 0.93 1.08

Water Absorption, max 1.3%

no blisters 0.99 1.12


by weight 37.6 29.7


Summary

• None of the sheet molding compounds discussed exhibited any issues during the manufacture and molding of the material.

• The new AOC Low Density resin systems exhibited results that were favorable to the Ford Low Density Structural Specification.

• Mechanical Properties exceed Ford’s specification WSS-M3D188-A.

• Some aesthetic results were superior to the surface characteristics shown for a standard density Class A system.

• AOC now has a Class A resin system that is currently in production on the Chevrolet Corvette. The Class A system has also been qualified at Ford and Chrysler. Other OEMS are in the process of qualifying the Class A system as well.


Summary

• We believe that the work done affords automotive OEMs the opportunity to immediately reduce the mass of Class “A” closure panels without having to change their manufacturing and assembly processes.

• These materials provide a cost competitive alternative to aluminum and carbon fiber composites and are readily available.

• Additional benefits include: greater design freedom, parts consolidation, lower tooling cost, dent/damage & corrosion resistance and excellent surface aesthetics.

• We are currently focusing on improving the Ultra Low Density versions for mechanical properties


JEFF KLIPSTEIN

AOC

TECHNICAL SERVICE SPECIALIST

(219)-465-4349 WORK

(219)-465-4337 FAX

(330)-242-3978 CELL

[email protected]

Current Advances in Low Density SMC for Automotive Class A … · 2016. 10. 28. · −Better if...

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