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Long-Fiber Reinforced ThermoplasticsTailored for Structural Performance
Manfred Brümmer
Dr. Frank HenningDr. Wenzel Krause
ACCE5th Automotive and Composites ConferenceTroy, USA, 12.-14. September 2005
- Page 2
Outline
Introduction
Advantages of Dieffenbacher LFT-D-ILC technology
Continuous fiber reinforced LFT
Tailored LFT – material development
Conclusions
Future Perspectives
Presses & More - Teaming up in development
- Page 3
Tailored
TailoredLFT‘s
Toughness
Stre
ngth
/ S
tiffn
ess
Rubber
Short fiber reinforced
plasticsLong fiberreinforced
plasticsParticle filled
plastics
Non reinforcedplastics
Why Long Fibers for Reinforcement ?
- Page 4
Fiberglass rovingPolymer resin Additive/modifier
Product – LFT part
Glass Mat Thermoplastics(semi-finished product)
GMT oven+
Hydraulic press
Long Fiber Thermoplastic Granules(semi-finished product)
GMTCompression molding
Single screw extruder+
Hydraulic press
LFT-GInjection molding
LFT-GCompression molding
Injection molding machine
Product – LFT part Product – LFT part
Established Processing Techniques for LFT Semi Finished Products
- Page 5Quelle: AVK-TV 2005
Growth of LFT in Europe
0
5
10
15
20
25
30
35
40
45
19941995
199619971998
1999200020012002
20032004
kto
GMT LFT
- Page 6
Product – LFT part
Polymer compound
LFI injection molding
equipment
LFT/SGInjection molding
LFT-D-ILC equipment+
Hydraulic press
LFT-DCompression molding
LFT-D-ILC compression molding
LFT-D extruder+
Hydraulic press
Product – LFT partProduct – LFT part
Fiberglass rovingPolymer resin Additive/modifier
In-Line Compounding
Technologies for LFT Direct Processing
- Page 7
Compounding extruder suitable for: BlendingIn-line Stabilization and CouplingIn-Line coloringEngineering resins/polymersIn-line compounding of fillers or nanoparticles
Mixing unit (twin-screw)Extraordinarily low wear (screw/cylinder)Incorporation of different continuous fibersIncorporation of natural fiber matsIncorporation of chopped fibersComplete disintegration of fiber bundles
Dieffenbacher LFT-D-ILC technology basis for visible applicationsDisintegration of fiber bundles and homogenous dispersionReduced anisotropy and therefore low warpage
Advantages of Dieffenbacher LFT-D-ILC Technology (2 Extruders)
LFT strand
Mixing extruder
IL Compounder
Polymer Additive/modifier
Fiberglassroving
Compression molding
DIEFFENBACHER
LFT strandLFT strandLFT strand
Mixing extruderMixing extruder
IL CompounderIL Compounder
PolymerPolymer Additive/modifier
Additive/modifier
Fiberglassroving
Fiberglassroving
Compression molding
DIEFFENBACHERDIEFFENBACHERDIEFFENBACHER
- Page 8
Advantages regarding material propertiesTailored LFT material Choice of matrix resin, additives and fibersAdjustable and reproducible fiber length distribution Continuously adjustable glass fiber contentExcellent homogeneity of LFT strandsCo-molding of continuous reinforcements at low thickness and weight compared to injection molding possibleSingle heat historyExcellent flow behavior Improved surface appearance (vs. GMT processing) Processing of recycled trimmings and even ELV material
Advantages regarding economical factsHigh productivityLow wall thickness possible compared to injection molding (material savings 25%)Low down time due to turnkey production cellSignificantly reduced expenses for total process energy consumptionHigh material output rates at constant and reproducible material propertiesExtremely short cycle times (22 seconds for VW Golf V underbody shield)Reduced mold and screw wear
Advantages of Dieffenbacher LFT-D-ILC Technology
- Page 9
In-line compounder
LFT die
Conveyor belt forLFT strand
HydraulicPress
Provision of rovings
Mixing extruder
Fully automized material handling
AVK-TV Innovationspreis
2001
LFT-D-ILC Base Equipment
- Page 10
What is Tailored LFT ?
LFT combined with local reinforcement by fabrics or continuous fiber structures
Next Generation of Composites in Automotive
- Page 11
LFT (Long fiber reinforced thermoplastics – pellets, granules)
Tailored LFT (LFT-D-ILC with local continuous fiber placement –rovings, profiles, textiles or combination)
GMTex (GMT with one/several layers of woven fabrics)
GMT (Glass-mat reinforced thermoplastics)
LFT-D (LFT with direct incorporation of glass fibers)
Alternative to metal or metal hybrids
Development Path
- Page 12
GMT + GMTexprecut
Ofen
Heated precut
PositioningIn mold
CrosswiseSheet placement
PartSource: Quadrant
Applications – Spare Wheel Tub
- Page 13
GMTex – Field of Applications
Source: QuadrantImproved crash performanceby combination of LFT and Fabrics
- Page 14
GMTex – Tailored LFT - Field of Applications
previous model:GMT + steel brackets
new model:GMTex + integrated brackets
Source: Quadrant
- Page 15
Production Technologies – Compression Molding of GMTexGMTex
Advantage- Synergy of co-molding (no high precision molds no
additional handling of textiles or organic sheets)- Local reinforcements just in areas where required- Reduced costs compared to the use of pure organic sheets
Disadvantage- Dependency on one material supplier- Costs of semi-finished products (incl. shipment and storage)- Co molding of standard GMT required- Fiber alignment is not optimal (0/90°)- No structural incorporation of inserts possible
Source: Quadrant
- Page 16
Tailored LFT - Adjustment of Mechanical Properties by In-Line Assembly of Continuous Fiber Skeleton with LFT-D
LFT
Fabric
Important parameters are :
Fiber orientation of each layer (fabric and LFT)Volume ratio of fabric and LFT (thickness of each layer) Properties of each layerProcess parameters (processing window)
simplified approximation:
EC = EG*vG + ELFT*vLFT
Calculation of Modulus utilizing therule of mixture:
- Page 17
75,7 89,9 90,9 91,8
130,1173,8
267,1
372
0
50
100
150
200
250
300
350
400
450
LFT-D30; 0° LFT-D30; +/-45°Gelege; 0°
LFT-D30;Twintex TPP601485AF; 1-lag;
0°
LFT-D40; 0° LFT-D40;Twintex TPP601485AF; 1-lag;
0°
LFT-D30;Twintex TPP60935BF; 2-lag;
0°
Twintexlaminat;TPP60
1485AF; 0°
Twintex laminatTPP60 935BF
4/1; 0°
Tens
ile s
tren
gth
[MPa
]
Fabric Reinforced LFT – Adjustment of Mechanical PropertiesThe variation of fabrics and LFT materials offers a material tailored for each application
- Page 18
Elongation of a TWINTEX laminate 45° (7 layers of Twintex P PP60 745 AF)
Local Reinforcement Using TWINTEX Fabrics
- Page 19
Textile Reinforcements - Tensile Strength PP/GF60 Laminates
Laminates of non crimped fabrics offer a high potential for energy absorption
0
50
100
150
200
250
300
350
400
0,00 5,00 10,00 15,00 20,00 25,00
Bruchdehnung [%]
Zugs
pann
ung
[MP
a]
Twintex 4/1 0°
Twintex 4/1 90°
Twintex +/-45° 0°
Twintex +/-45° 45°
Saertex +/-45° 0°
Saertex +/-45° 45°
Saertex 45°/90°/-45° 0°
Saertex 45°/90°/-45° 90°
Elongation [%]
Tens
ile S
treng
th [M
Pa]
- Page 20
Advantages and Challenges of Local Textile ReinforcementsSignificant increase of Tensile Modulus and Strength
Significant increase of impact and energy absorption
Slight increase of flexural strength and modulus (low wall thickness!)
Material properties = properties of the component
but
Warpage…+
…Penetration of the fabric by LFT…+
…Influence of geometry =
= have to be considered in the design phase!
- Page 21
30 c
m
7,9
27,830,5
134
44
144
0,0
5,0
10,0
15,0
20,0
25,0
30,0
35,0
LFT-D with-out rovingstructure
rovingstructure
Rovingstructureco-moldedwith LFT-D
Ten
sile
Stre
ng
th[k
N].
0
100
200
300
400
500
600
700
Part
wei
gh
t[g
]
ICT-DemonstratorContinuous fiberstructure co-moldedLFT-PP/GF
Tailored LFT – Light-Weight Composite Parts Made of Long Fiber Reinforced and Continuous Fiber Reinforced Thermoplastics
• Customized unidirectional continuous fiber structures for significant increase of part specific strength (increase of some 100%).
• Transmission of forces by part specific continuous fiber structures -fiber structures work as an superior integrated joining technology
Demonstrator:LFT-PP/GF
combined with continuous
fiber structure
- Page 22
Filament woundreinforcement UD-profile reinforcement
Fabric reinforcement
Integration of Different Types of Local Reinforcements
- Page 23
Fusion Bonding of LFT and Continuous Fiber Reinforcements
Cohesion and Adhesion
Fusion Bondingbetween
LFT and films
Cohesion force(equal join partners)
Interdiffusion atpolymer-polymer-interface
(LFT / Reinforcement)
Adhesion force(different join partners)
Form fit(surface roughness)
- Page 24
Heating of thefabric in an infra-red oven
Transfer of fabric to the open mold
Two LFT-strandsare positioned inthe mold
Compressionmolding of fabricand LFT-material
Setup to Produce Co-molded LFT/Fabric Sample Plates
- Page 25
Preheat temperature of reinforcement (important for handling)
mold LFT fabric mold
Preimpregnated fabric: PP/GF60LFT-D: PP/GF30
Example:TLFT = 230°CTInterface ≈ 185°CTFabric = 140°CTMold = 60°C
Tmold
TPPm
Interface temperature exceeds the melt temperature for a short time(Process window)
t1
t2
t3
t4
Temperature Curve at Non-Isothermal Bonding
- Page 26
100µm
Uneven polymer-polymer interface
Filaments crossing thepolymer-polymer interface
Bond strength is based on interdiffusion, fiber bridging, andmechanical adhesion due to an uneven surface in the interface
Micrograph of the Interface LFT/ Reinforcement
- Page 27
Penetration in the demonstrator part (beam structure)
No penetration
Standardmold filling
Penetration,
Mold-fill trough the fabric
LFT-Material
Mold withrib cavity
Function integration on bothsides of the fabric
molding
Fabric
Penetration of Fabrics with LFT-Material
- Page 28
Functional Integration in a Front-End Carrier (by Penetration)
- Page 29
highly oriented fibers
Reduction of glass content from 29,9 wt.-% to 26,9 wt.-%
(Fabric: Twintex P PP60 935 BF 4/1)
Rib structure of demonstrator part (LFT PP/GF30)1. Row no Penetration2. Row penetrated areas
X-ray Images of Penetrated Areas
- Page 30
020406080
100120140160
0 10 20 30 40 50Torsion Angle [degree]
Torq
ue [N
m]
180
LFT-beam structure with continuous fiber reinforcementLFT-beam structure without continuous fiber reinforcement
1,5 °/s
350 mm
Improvement of Torsional Strength by Local Reinforcement
Adding an roving reinforcement:Beam weight increase by 4% compared to pure LFT-PPGF30
- Page 31
Filament woundroving reinforcement
Metal insert
LFT-part with co-molded reinforcement
(with and without metal inserts)
Part dimensions: Length: 300 mmPart weight: 150 gAdditional weight for UD-Reinforcement: 10 g
Loop Reinforcement Between Fixtures – Load Path
- Page 32
Number of layer
X
Y
ZTesting directions:
0
10
20
30
40
50
0 10 20 30 40 50Number of layers (glass-roving)
Froc
e at
bre
ak [k
N]
Test in X-directionTest in Y-directionTest in Z-direction
The part strength is improved by a factor of 10 in all three directions
Mechanical Properties of a Co-molded Continuous Loop Structure
- Page 33
Filament woundreinforcement
LFT forfunctional integration
Rovingstructure
Fabric-reinforce-ment
PressLFT-material
Robot
UD-reinforcement is preheated as a tailored Preform LFT-material and UD-reinforcement are assembled in-line to the compression molding step
Production Concept for a Tailored LFT Composite Frontend Carrier
- Page 34
Process Development and Modification for Tailored LFTPrototype Manufacturing
- Page 35
Tailored LFTAdvantage- Synergy of co-molding (no high precision molds no
additional handling of textiles or organic sheets)- Local reinforcements just in areas where required- Reduced costs compared to the use of pure organic sheets- Reduced costs compared to the use of semi-finished products (GMTex)- Independency from material supplier- Optimimum fiber alignment and structural integration of inserts- Combination of geometrical stiffening (ribs) and material stiffening (continuous fiber)- Improvement of impact by additional fabric possible if necessary (integrity after crash)
Disadvantage- Higher degree of automation due to profile positioning / equipment (not cycle time
relevant)- New development – not state-of-the-art, some development necessary
Production Technology – Tailored LFT
- Page 36
Bumper Beam madeof Tailored LFT
Advantages of automised local fiber placement:
Reduced material cost
Economical use of continuous fiberreinforcements
Reinforcement is tailored to thespecification
High level of functional integration
Advancements of Tailored LFT
- Page 37
LFT-D Technology avoids the use of semi-finished products
LFT-D parts can be reinforced withcontinuous fiber reinforcements
Wide processing window allows goodbonding of LFT and reinforcement
Co-molding combines high functionalintegration and the performance of continuous fiber reinforced composites
Source :Quadrant
Door modules
Front ends
Spare wheel pan:Fabric reinforcement (GMTex)
Conclusion
- Page 38
Future/Perspectives
LFTs with engineering plasticsApplication of technical plastics (ABS, SAN, PA 6, PA 6.6, PBT, etc.)
LFTs with other fibers/filling materialsApplication of natural fibers (Flax, Sisal, Hamp, etc.)Application of additional filling materials (Talc, hollow glass beads, etc.)
Exterior body panels - „LFTs and PFM“Back compression molding of films (PFM – Paintless Film Molding)
Development of process technology, material and equipment for the use of:
- Page 39
Dieffenbacher „Engineering Area“
Equipment consisting of features that areClose to real production and different ways oftreatment:
Hydraulic High Speed Press 36.000 kN (End 05) with an active parallel levelling systemLFT-D PlantLFT-G Extruder for granulesConveyor and dosing plants for various plasticsgranules and recyclesAdjustable die for tailored plastificates
Research and DevelopmentDevelopment of new process technologies and modifications suitable for the processing of longfiber-reinforced thermoplastics and -setsSupport for part design by Dieffenbacher Competence Team Simulation of Mold filling by Fraunhofer ICTMatching and prototype productionMaterial development in cooperation withFraunhofer ICT
- Page 40
Closing Words
The In-line Compounding-Compression Process is an established technology for long fiber reinforced components which offers a high development potential for future applications especially for structural and semistructural parts as well as for car body parts aiming at class „A“ surface quality.
www.dieffenbacher.dewww.ict.fraunhofer.de
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