Joining in Car Body 2012, Bad Nauheim, 18.04.2012

Innovative solid-state spot joining methods for fiber composites and metal-polymer hybrid structures

Prof. Dr.-Ing. Sergio Amancio

Institute of Materials Research - Materials MechanicsSolid State Joining Processes (WMP)“Advanced Polymer-Metal Hybrid Structures” Group

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Contents

Introduction

Challenges and Motivation

Friction Riveting

Friction Spot Welding / Joining

ICJ Method

Final Remarks

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Introduction

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Helmholtz Association:Facts and Figures

17 research centres with more than 240 institutes

31.000 staff9700 scientists and engineers

5.320 doctoral students

Budget: 3,3 billion €

List

Helgoland

Bremerhaven GeesthachtHamburg

Greifswald

Braunschweig

Wolfenbüttel-Remlingen

Göttingen

Magdeburg

Potsdam

Berlin

ZeuthenTel tow

Niemegk

Halle

LeipzigBad Lauchstädt

KölnJülich

Bonn

Darmstadt

HeidelbergLampoldshausen

Karlsruhe

Stuttgart

Münc hen

GarchingNeuherberg

Oberpfaffenhofen

Helmholtz Center

Helmholtz Head OfficeBranch of a Helmholtz center

4

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Helmholtz-Zentrum Geesthacht

860 staff (incl. 281 scientists/128 guest scientists + 127 ongoing PhD thesis)

3 Research institutes, 8 Directors of institutes81 Mio € total budget (2007), 13,5 Mio € 3rd-party (incl. industry)271 ISI publications (2007)> 50 apprentices

From application-oriented

fundamental research to innovation

Teltow

Geesthacht

5

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Est. in 1992

Scientific and Technical Staff in 2011: about 30 fellows

Competence Areas of Research

FSW Process

Residual Stress & Distortion

Friction-based Joining Processes

Polymer-Metal Joining

Hybrid Solid State Processes

Metallurgy of Welding

Solid-State Joining ProcessesDepartment (WMP)

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Workgroup Group @ HZG

- Students: 1 Postdoc, 3 PhD, 4 MSc and 1 undergraduation students

Integrated in the Institute of Polymer Composites at Hamburg University of Technology (TUHH) through an Assistant Professorship in Joining of Polymer-Metal Hybrid Structures

++ =

“Advanced Polymer-Metal Hybrid Structures” Group

7

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Process development

Properties of the interface (bonding mechanisms)

Mechanical, physical-chemical, thermal and microstructural properties of polymer composites / lightweight metal hybrid structures

R&D Strategy

JOINING TECHNOLOGY

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Car Manufacturers

Suppliers:

Material Supplier

Network of Partners in the Automotive Sector

PAGE 9

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Challenges and Motivation

PAGE 10

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Challenges in Joining Polymer to Metals and Composites

Physical-chemical dissimilarity

- Different Cohesion and Surface Energies. Low miscibility!

- Difference in Coefficient of Thermal Expansion and Heat Capacity can lead to separation distortion of parts

- Reduced Thermal Resistance of the polymer can lead to thermal degradation

For composites

- Avoid damage or modification of the network of fibres

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Motivation

CFKMagnesium

Increased use of polymer-metal hybrid structures in the engineeringapplications (weight reduction and decrease in CO2 emissions )

Available joining methods for those structures are either complex, expensive or not environmental friendly

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Joining Technologies for Polymer-Metal Hybrid Structures(S. Amancio and J.F. dos Santos, Polym. Eng. Sci., 2008)

State of the Art

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Friction Riveting(FricRiveting)

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Amancio, 18.04.12 15Blaga • 02.04.2012 15

FricRiveting is a innovative spot joining technique for polymer-metal structures (US Patent US 7 525 149 B2 (2009))

Based on mechanical fastening and friction welding

Cylindrical metallic rivet is used to join thermoplastic components

Prize-winning joining technology: RSM 400 Friction Welding (Harms & Wende GmbH)

Friction Riveting - FricRiveting

- Spindel: RSM 400- Rotational Speed: max. 23000 rpm- Nominal Power: 1,8 kW- Axial Force: max. 6 kN (≈ 10 bar)

- Granjon Prize 2009

- Nordmetall Preis 2008, Germany

- SPE-ANTEC 2008, USA

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FricRiveting

Positioningof the

Partners

Rotating RivetInsertion &

Polymer Melting

Plasticizing of the Rivet & Forging

Anchoring of theforged rivet &

JointConsolidation

Time

Principles of the process

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Microstructure: PEI / Al 2024

Polymer-Polymer Interface

Metal-PolymerInterface

(adhesion)

PAGE 17

FricRiveting

TMAZ: DRX- grains

BaseMaterial

Amancio, 18.04.12 18Blaga • 02.04.2012 18

Results and Discussions

5.65

3.50

4 mm 5.30

4.80

Glass fiber woven is shifted to about 45 degrees to the upper face of the composite

Fiber network remains in contact with the rivet shaft

Reduced amount of thermal flaws

4 mm

Ti alloy / GFR PEI: Microstructure

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Al 2024 / PEI :Tensile Strength (Avg. Curve of 5 Samples)

PAGE 19

Fmax= 9,7 ± 0,7 kN

Joint Strength ≈ RivetStrength

FricRiveting

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FricRiveting

v

v

Smaller Plunge Depth ( heat input)

Larger Plunge Depth ( heat input)

L. Blaga, S.T. Amancio-Filho et al. ANTEC 2012

Ti alloy / GFR PEI :Tensile strength

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Al 2024 / PEI : Lap Shear Strength (avg. of 5 samples, ASTM D5961)

Rm= 77,5 ± 0,1 MPa

Shear Strength ≈ 70% of PEI plaque

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FricRiveting

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Current Developments

Lap-shear specimen

Avg. lap shear strength of 200 MPa

Failure through shear of the metallic rivet

Friction riveted have similar behavior and mechanical performance as bolted joints!

Ti alloy / GFR PEI : Lap Shear Strength (ASTM D5961)

Bolted specimen

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Current Investigations

FricRiveting

Medical Polymers / Ti alloys(HZG-CCDM)

Automotive Plastics / Al alloys(C. Rodrigues, MSc-Thesis)

1000 2000 3000 4000 5000 6000 7000 8000 9000

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9000 Experimental Validation

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dic

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Experimenta l1000 2000 3000 4000 5000 6000 7000 8000 9000

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Current Investigations

FricRiveting

Modelling of Mech. Properties(M. Borges, MSc-Thesis)

GFRP / Ti alloys(L. Blaga, Postdoc)

Temperature Modelling

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Friction Spot Weldingof Thermoplastics

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- Developed and patented by HZG (US Patent No. 6722556B2)

- Refilled Spot (no keyhole in the welding region)

- For both metals and polymers, FSpW shows better mechanical properties than FSSW

- Similar or better mechanical performance in comparison to other spot welding techniques1

1 P. Oliveira, S. A mancio-Filho, J. dos Santos, E. Hage Jr., Mater. Lett., 64, 2098-101 (2010)

Principles

Friction Spot Welding

RSM 100 (Harms & Wende GmbH)

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Friction Spot Welding

Principles

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Weld Line

Joel Gonçalves • 10.02.12

Breaking and reorientation of

the fibers

FSpW of PA 66-CF - Microstructure

Structure of the CF laminate

Broken Fibers

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Rotation(rpm)

Plunge Depth(mm)

Plunge Time (s)

Retracting Time (s)

Pressure(bar)

Holding Force Time(s)

3000 2,2 2,3 4,5 3,0 20

Surface Finishing

Fracture Surface

Upper

Lower

Upper Lower

FSpW of PA 66-CF – Mech. Properties

Mechanical Properties

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Current InvestigationsFriction Stir /Stir Spot Welding

and FSpW of PMMA(P. Oliveira, MSc-Thesis)

Friction Spot Welding ofPA 6 / PA66-CF

(J. Gonçalves, MSc-Thesis)

Friction-based Spot Welding of Thermoplastics / CRFP

PA6

PA6

PA6PA66-CF

PA66-CFPA66-CF

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Friction Spot Joiningof

Metal-Composite Structures

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European Pat. Appl. EP 09015014

Shallow tool plunges (0,2-0,3 mm)

Metallic material is heated up and formed locally

Joint achieved by adhesion forces (consolidated polymer) and mechanical interlocking (metallic nub)

Distinction Prize (Sonderwürdigung), 2011

Friction Spot Joining of Composite-Metal Joints

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claded aluminium layer

Cross sectional view of the joining partners

S. Goushegir, S.T. Amancio-Filho HZG, 2011

Alclad 2024-T3 / PPS-CF

Microstructure

Friction Spot Joining of Composite-Metal Joints

claded aluminium layer

fibers covered by thecladed aluminium layer

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fibers attached to thealuminium surface

Avg. lap shear resistance (ASTM D3528–96) :

2570 N (40 MPa)

(surface treatment: grit paper P1200)

10 mm

10 mm

Friction Spot Joining of Composite-Metal Joints

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Mechanical Performance of FSp Joints

Attempt to evaluate current strength of FSpJwith state-of-the-art joining technologies:

- Similar geometries and failure mechanisms

- Different base materials

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Al 5

754

AZ 3

1

Al 6

181

54 M

Pa

40 M

Pa (

Al 2

024)

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Current Investigations

Friction Spot Joining of Composite-Metal Joints

Al 5754 / CFRP(T. Rocha, Dipl. -Thesis)

Al-CFRP Double Lap Joints(J. Esteves, MSc-Thesis)

AZ31 - Composite InterfaceProperties

(C.Bueno, Dipl. Thesis)

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Injection Clinching Joining(ICJ)

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New spot joining process for thermoplastics and metals (HZG Patent, DE 10 2005 057 891.8 2005)

Based on principles from injection moulding, adhesive bonding and staking

Tooling: Electrical Heating and Frictional Heating

Prize of PPS-2010 Banff, Canada

Injection Clinching Joining (ICJ)

X

Frictional heatingElectrical heating

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Electrical Heating ICJ

Main parameters: heating time and heating temperature

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ABIBE, A.B et al., J Thermop Comp Mat, 2011

Polymer

Metal

Electrical Heating ICJ

Excellent mechanical performance

Better cavity filling results in higher global

Mechanical properties

Limitations: long joining times and high energy consumption

88,5%

35,9%

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Friction-based ICJ

Energy efficient

Faster cycles

Simpler tooling

Main Parameters

- Rotational speed

- Joining time

- Joining pressure

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Equipment: RSM400

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PA66 30%GF / Al 2024 ( Process duration: 3s -5s)

PA66-FG30%AA2024-T351

Friction-based ICJ

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AdvantagesLittle or absent surface cleaning /

preparation.

Easy accessibility

Joining is independent of position.

Short joining cycles (0,5 to 10 s)

A wide range of materials and can be joined

Hermetic sealed joints

Simple and low cost machinery. Robotic application is also possible

Joints with good tensile and shear performance

LimitationsOnly spot-like joints

Not applicable for thermoset polymers, without selecting optimized joint geometries

non-reopenable joints

Minimum thickness of the polymeric partner(s). Nevertheless, this can be reduced by altering geometry of joint

Tool wear in FSpW of CFRP (not in FSpJ!!!)

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Advantages & Limitations

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Joinability of Polymer-Metal structures is strongly dependent on thelevel of properties dissimilarity

Solid-State Joining Processes are innovative technologies forenvironmental friendly and cost effective lightweight design

The know-how in Polymer-Metal Joining is an asset for theincreasing market competition in the field of multi-material lightweight design

Final Remarks

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Potential Applications ?

Alternative processes to adhesively bonded, riveted and bolted joints?Adequate for joints between TPO and Engineering Plastics and Composites (FricRiveting)As local reinforcement for bonded structures (FSpJ)?As alternative to currently available spot welding (FSpW)Input / Feedback from the Automotive Engineering Community!

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Financial Support

Acknowledgements

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Prof. Dr.-Ing. Sergio AmancioE-mail: sergio.amancio@hzg.de

Tel.: +49 4152 872066

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