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Adhesive Bonding for Aluminum Lightweight Structures
SAE Webcast November 18, 2014
Mansour MirdamadiDow Automotive Systems
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Presentation Outline
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• The key drivers in use of adhesive bonding
• Challenges and consideration in selection of adhesive
• Adhesive bonding product categories
• Case studies
• Future outlook and development
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Why Adhesive Bonding?
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Fuel Efficiency
CO2 Compliance
Sustainability TargetsBETAMATE™ and BETAFORCE™
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Adhesive Bonding of Lightweight Materials
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• Enable use of lightweight structural materials such as
aluminum, magnesium, steel, and composite systems
• Maximize the use of OEM assembly and joining capabilities
• Challenges with multi-material design– Coefficient of linear
expansion – Da
– Heat/thermal capacity – D
– Residual stresses
– Component distortion due to thermal and mechanicalloads
– Impact of residual stresses on adhesion performancestrength,
fatigue/durability, and corrosion
– Electrochemical potential, i.e. galvanic corrosion
– Hybrid joining
– OEM/tier part, component, sub-system assembly
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Key Factors in Adhesive Selection Criteria
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• Understanding the mechanism for adhesive bonding
– Adhesion
• Mechanical interlocking
• Chemical bonding between the adhesive and the aluminum oxide
or pre-treatment
• Impacted by the chemistry of the surface and the
morphology
– Surface wetting characteristics
– Interface
• Adhesive bond durability
• Component assembly
Systematic Approach
Adhesive
LubricantsPre-
treatment
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Influence of Coefficient of Thermal Expansion
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BETAMATE A, E = 1,700 MPa
BETAMATE B, E = 4,000 MPa
BETAMATE C, E = 2,800 MPa
Adhesive thickness: 2-3 mmSteel substrate: 0.5 mmCure: 180 °C,
30’
Adhesive thickness: 0.25 mmSteel substrate: 1.0 mmAluminum
substrate: 1.0 mmCure: 180 °C, 30’
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Dow Automotive Systems BETAMATE™ and BETAFORCE™
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BETAMATE Technology
1K PU
BETAFORCE Technology
BETAMATE Technology
2K PU
CDA
2K EP2K PU
BETAFORCE Technology
BETAFORCETechnology
Structural PU Structural PU
Body Shop Paint Trim Shop Repair80-160 ˚C, 30’180 ˚C, 30’ 25
˚C
Standard to Fully Toughened
Structural Parts
1K EP
2K EP
Structural Parts
Hang-on Parts and Closures
1K – one component2K – two componentEP – epoxyPU -
polyurethane
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Dow Automotive Systems BETAMATE™ and BETAFORCE™
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Overview 1K EPBETAMATE
2K EPBETAMATE
1K PUBETAFORCE
2K PUBETAFORCE
E-Modulus (MPa) 100-6000 500-3000 10-300 10-300
Tensile Strength (MPa) 10-60 10-40 10-20 10-20
Tg (°C) 90-150 °C 70-110 °C - -
Impact Strength (N/mm) 10-60 8-30 - -
Thermal Stability (°C) Up to 220 °C Up to 220 °C Up to 150 °C Up
to 150 °C
Typical Curing 180 °C, 30 min 2-7 d, RT60 °C, 2 h
2-10 min, 90-110 °C (full cure)
RT
Pre-curing Induction, oven, microwave
IR, Induction, oven IR, Induction, oven IR, Induction, oven
Handling strength Pre-cure 40 min - 8 h, RT Pre-cure 3-20 min,
RT
Mixed-material bonding Good-excellent Good-excellent
Good-excellent Good-excellent
Oil absorption Yes Some No No
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Future Outlook
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• Structural applications, and load-carrying components
– Improved fatigue resistance
– Robust adhesion to aluminum alloys
– Robust adhesion for multi-material joining
– Enhanced corrosion protection under corrosive environment
while under constant load
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Future Outlook
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• Hang-on parts, and closure systems aluminum-to-steel bonding
for body shop applications
– Focused on minimal aluminum surface distortion with long
distances between mechanical fixation between aluminum to steel
No Adhesives
Development Hybrid Adhesive
1K Standard Epoxy
1k CDA
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Future
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Optimized for OEM and tier assembly operations
BETAMATE™ Epoxy & BETAFORCE™ PU Technology
Hybrid Technology and New Chemistries
