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Compression RTM - A new process for manufacturing p p ghigh volume continuous fiber reinforced composites
5th International CFK-Valley Stade Convention
07-08 June 2011, STADEUM Stade, Germany
Authors R Ch dh i Mi h l Pi kRaman Chaudhari, Michael Pick,
Oliver Geiger, Dennis Schmidt,
Prof Dr Ing Peter ElsnerProf. Dr.-Ing. Peter Elsner
Prof. Dr.-Ing. Frank Henning
Contents
Motivation and Goal of this Feasibility Study
State of the art: Resin Transfer Molding (RTM) ProcessState of the art: Resin Transfer Molding (RTM) Process
High Pressure RTM Processes
Definition of CRTM process parameters
Compression RTM process study
Process equipment
Experimental designExperimental design
Results and Discussion
Summary and Outlook
Acknowledgement
© Fraunhofer ICT
Motivation and goal of this feasibility study
Applications for high performance composite parts in the automotive industry
Side frameFloor structure
Audi R8 Spyder
Source:Alcan
RoofBumper BMW M6BMW M6
BMW Project I CityCar
Quelle: BMW
© Fraunhofer ICT
Quelle: BMW
Motivation and goal of this feasibility study
Development of a new processing strategy for the manufacturing of
high-performance thermoset composite parts in shorter cycle timeg p p p y
To overcome the issues of the standard resin transfer molding process
The new process strategy should fulfill the following requirements
Excellent material and part performance
Nice surface of the parts
Short cycle timesShort cycle times
Capable for the utilization of fast curing resins
Large scale production capability
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State of the art: Resin Transfer Molding (RTM) ProcessRTM Process cycle
3D PreformPreform production
and fixing
H dli i fi i h d
Preform handling
Mold technology
Fixing 2D-semifinished
Handling semi-finished product
gy
Infiltration and curing
Resin Hardener
gfabric product
and curing
Component demoldingand post processing
Textile product
Semi-finished fabric cuts 2D and post-processing
RTM componentMold cleaning
Start of cycle End of cycle
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State of the art: Resin Transfer Molding (RTM) ProcessRTM Process cycle – Injection sequence
The dry 3D fiber preform is placed into the open mold cavity and the mold cavity is closed completely (gap in the cavity = final wall thickness)cavity is closed completely (gap in the cavity = final wall thickness)
Resin and hardener are mixed and then injected into the cavity
Injected resin impregnates the preformInjected resin impregnates the preform
Demolding of the part after curing
Resin Hardener
Dry 3D fiber preform in completely closed mold
Resin injection, preform impregnation and curing of the part
Demolding of the cured RTM part
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completely closed mold and curing of the part cured RTM part
State of the art: Resin Transfer Molding (RTM) Process
Typical challenges and issues of the state of the art RTM process
Typical injection pressure between 1 and 20 barTypical injection pressure between 1 and 20 bar
Higher pressure disturbs the fiber orientation in the preform
Permeability of 3D fiber preform influences significantly the injection timePermeability of 3D fiber preform influences significantly the injection time
Proper impregnation of complex shaped preforms is a challenge
Required injection time does not allow the use of fast curing resin systems
Typically long cycle times due to long injection and curing times
Additional resin required to push trapped air out of the mold cavity
Negative economical and ecological impact
Probable solutions: High Pressure RTM processes
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High pressure injection RTM Process (HP-IRTM)HP Injection RTM Process cycle – Injection sequence
The dry 3D fiber preform is placed into the open mold cavity and the mold cavity is closed completely (gap in the cavity = final wall thickness)cavity is closed completely (gap in the cavity = final wall thickness)
Resin and hardener are mixed under high pressure and then injected into the cavity at leading to high pressure built up in the cavityy g g p p y
Injected resin impregnates the preform mainly due to flow in in x-y plane
Demolding of the part after curingg g
Resin Hardener
Dry 3D fiber preform in completely closed mold
Resin injection, preform impregnation and curing of the part
Demolding of the cured RTM part
© Fraunhofer ICT
completely closed mold and curing of the part cured RTM part
High Pressure Compression RTM Process (HP-CRTM)Compression RTM Process cycle – Injection sequence
The dry 3D fiber preform is placed into the open mold cavity and the mold cavity is partially closedcavity is partially closed
Resin and hardener are mixed and injected into the mold gap at low cavity pressurep
The mold is then closed completely, high pressure is applied and the preform is completely impregnated and cured before demolding of the part
Resin Hardener
Dry 3D fiber preform in partially closed mold
Resin injection and partial preform impregnation
Apply pressure, complete preformimpregnation and curing of the part
Demolding of the cured RTM part
© Fraunhofer ICT
p y p p g p g g p p
High Pressure RTM Processes
High Pressure Injection Resin Transfer Moulding
High Pressure Compression-Resin Transfer MouldingResin Transfer Moulding
HP-IRTMResin Transfer MouldingHP-CRTM
Impregnation of preforms in x- and y- direction
Impregnation of preforms in x-, y- and z- direction
© Fraunhofer ICT
High Pressure Compression RTM Process (HP-CRTM)
Advantages and challenges of the Compression RTM process
Increased permeability of fiber preform due to open mold gapIncreased permeability of fiber preform due to open mold gap
Thus also reduced time for resin injection
Si ifi tl d d ti f f i ti th h hi hSignificantly reduced time for preform impregnation through high pressure
compression
Fast injection and impregnation allows the use of fast curing resins
Almost no additional resin required to push trapped air out of the mold cavity
Positive economical and ecological impact
Reduced cycle times (depending on part geometry, fiber architecture and
resin)
Challenge: Suitable mold technologies required (injection port, sealing etc.)
© Fraunhofer ICT
Definition of CRTM process parametersImportant process parameters affecting CRTM process
Fiber volume content
It can strongly affects the required compression force and the impregnation quality
Resin viscosity / Resin temperature
It can influences the impregnation quality in the CRTM process
Cavity pressure / Compression pressure
It can affect the impregnation beha ior in correlation to the resin iscosit and fiberIt can affect the impregnation behavior in correlation to the resin viscosity and fiber volume content
Mould gap and gap closure speed
It can mainly influence the impregnation during injection (mould gap) and flow of the resin in the cavity (gap closure speed) and hence the impregnation behavior
Injected resin amountInjected resin amount
It can mainly influence the impregnation during injection / degree of mould filling during injection
© Fraunhofer ICT
Compression RTM process study
Literature research to eventually derive process parameters
Fib l Cl i M ld C i R i I j ti I j ti M ld C itLiterature Fiber volume content
Closing speed
Mold temperature
Curing temperature
Resintemperature
Injection time
Injection pressure
Moldgap
Cavitypressure
[%] [mm/min] [°C] [°C] [°C] [s] [bar] [mm] [bar]
Kang, M. [1999]: "Analysis of resin transfer compression
molding process"24 27 27 27 2
Chang C [2006]: "Effect ofChang, C. [2006]: Effect of process variables on quality
of CRTM"25, 50, 75 80, 100, 120 25, 32, 40 1, 1.5, 2 1, 5,
10 1, 1.5, 2
lkegawa, N. [1996]: "Effect of compression process on 33 5 100 130 130 90 0 5 13 0, 3, 6,of compression process on void behavior in structural
resin transfer molding"
33 5, 100 130 130 90 0,5 13 0, 3, 6, 12
PHAM, X. [1999]: 1 5 3 0 90, 30- - 4 8 2
5.1 3.1
"Simulation of CRTM for thin shells"
18, 33 1.5, 3.0, 7.5, 15, 30 60, 14, 8,
8
-, 4.8, 2, 3.5, 7 (final
thickn.)
© Fraunhofer ICT
Compression RTM process study
Process equipments
I j ti i tInjection equipment:
Wolfangel two-component RTM mixing and dosing equipment
Compression press:
Dieffenbacher DYL 630/500 hydraulic press, 6,300 kN press force
Compression RTM mold:
Plate mold 830 mm x 210 mm x 3 mm
© Fraunhofer ICT
Compression RTM process study
Materials
Saertex non-woven fabric (S14EU960-01210-01300-487000)
UD
MC Sizing,
1218 g/m²
Epoxy resin system
Hexion RIM 935 and RIMH 936
Resin-/Hardener mixture:
100:29 (wt.-%) / 100:35 (Vol.-%)
Resin mixture viscosity: 340 mPa*sResin mixture viscosity: 340 mPa s
© Fraunhofer ICT
Compression RTM process study
Experimental design
Fibre orientation
Resin temp.
Resin amount
Injection pressure
Cavity pressure Mould gap
Gap closure speed
Mould filling time
[°C] [g] [bar] [bar] [mm] [mm/s] [s]
RTM [04] RT --- 6-10 bar --- --- --- 400
CRTM 1 [0 ] RT 260 max 6 60 1 0 2 30 33CRTM 1 [04] RT 260 max. 6 60 1 0.2 30-33
CRTM 2 [04] RT 260 max. 6 60 2 0.2 30-33
RTM [0/90]s RT --- max. 6 --- --- --- 400[0/90]s a 6 00
CRTM 3 [0/90]s RT 260 max. 6 60 1 0.2 30-33
CRTM 4 [0/90]s RT 260 max. 6 60 2 0.2 30-33
© Fraunhofer ICT
Compression RTM process study
Materials characterization program
ILSS samples 15mm x 30mmILSS samples 15mm x 30mm
Flexural test samples 15mm x 90mm
Fiber vol. content Ø 30 mm
Tensile test samples 15mm x 250mmp
2 4
1 33
2
5 46
51
12345
3
2
1
2
3
1 2
4
3
2
1
ILSS samples away from injection point ILSS samples close to injection point
© Fraunhofer ICT
Results and discussions
RTM experiments
N i t d P ti ll i t d f b iNon impregnated area Non impregnated areaPartially impregnated fabrics
It was not possible to obtain complete impregnation of the fibers even after 400s injection time in the classical RTM process at 6-10 bar injection pressure
Hence it was not possible to characterize the mechanical properties of the plates manufactured by the classical RTM process
© Fraunhofer ICT
Results and discussions
Tensile properties of the CRTM laminates1200 Tensile strength
45
50
Tensile modulus
800
1000
gth
[MPa
]
25
30
35
40
lus[
GPa
]
70
80
me -%
]
Fiber volume content
3
4 Part thickness
s (m
m)
1147 1131
596 561
45,85 46,12
31,82 30,77
200
400
600
Ten
sile
stre
ng
10
15
20
25
Ten
sile
mod
ul
58,51 60,05 59,37 61,15
30
40
50
60
Fibe
r vo
lum
cont
ent [
Vol
-
0
1
2
Part
thic
knes
s
Non crimp fabric[0 ]
Non crimp fabric[0 ]
Non crimp fabric[0/90]
Non crimp fabric[0/90]
Non crimp fabric [04]
CRTM
Non crimp fabric[04]
CRTM
Non crimp fabric[0/90]SCRTM
Non crimp fabric[0/90]SCRTM
0
200
0
5
[04]CRTM
1mm Gap
[04]CRTM
2mm Gap
[0/90]SCRTM
1mm Gap
[0/90]SCRTM
2mm Gap
1mm Gap 2mm Gap 1mm Gap 2mm Gap
Nearly equivalent part thickness and hence fiber volume content was observed i th CRTM l i t t 1 d 2 ldin the CRTM laminates at 1 mm and 2 mm mold gap
Almost identical tensile properties of the CRTM laminates
© Fraunhofer ICT
Results and discussions
Flexural properties of the CRTM laminates
1200
1400 Flexural strength
45
50
Flexural modulus
70
80
me -%
]
Fiber volume content
3
4 Part thickness
s (m
m)
800
1000
1200
gth
[MPa
]
30
35
40
58,51 60,05 59,37 61,15
30
40
50
60
Fibe
r vo
lum
cont
ent [
Vol
-
0
1
2
Part
thic
knes
s
Non crimp fabric[0 ]
Non crimp fabric[0 ]
Non crimp fabric[0/90]
Non crimp fabric[0/90]
1270 12281139
103737,27 37,5133,58 33,51
400
600
Flex
ural
stre
ng
10
15
20
25
[04]CRTM
1mm Gap
[04]CRTM
2mm Gap
[0/90]SCRTM
1mm Gap
[0/90]SCRTM
2mm Gap
Non crimp fabric [04]
CRTM
Non crimp fabric[04]
CRTM
Non crimp fabric[0/90]SCRTM
Non crimp fabric[0/90]SCRTM
0
200
0
5
10
Almost identical flexural properties of the UD CRTM laminates at both mold gaps
CRTM1mm Gap
CRTM2mm Gap
CRTM1mm Gap
CRTM2mm Gap
Flexural properties of [0/90]s laminates significantly high due to presence of UD layer from top and bottom side; a slight drop of flexural strength observed at 2 mm mold gap
© Fraunhofer ICT
g p
Results and discussions
ILSS of the CRTM laminates ILSS Away from injection point
ILSS Close to injection point70
80
j p
50
60
70
Pa]
Fiber volume content (Away from Injection point)
Fiber volume content (Close to Injection point)
80
m]
4
Part thickness (Close to Injection point)
Part thickness (Away from Injection point)
59,35 58,83
34,87
57,89 57,58
32 71 33 4520
30
40
ILSS
[MP
58,92 60,39 58,08 63,7758,34 59,86 60,08 59,41Fibe
r vo
lum
e co
nten
t [V
ol-%
]
30
40
50
60
70
Part
thic
knes
s [m
m
0
1
2
3
34,8729,4532,71 33,45
Non crimp fabric [04]
Non crimp fabric[04]
Non crimp fabric[0/90]S
Non crimp fabric[0/90]S
0
10
30 0Non crimp fabric
[04]CRTM
1mm Gap
Non crimp fabric[04]
CRTM2mm Gap
Non crimp fabric[0/90]SCRTM
1mm Gap
Non crimp fabric[0/90]SCRTM
2mm Gap
Almost identical ILSS properties for UD laminates at 1 mm and 2 mm mold gap b d i j ti i t d f i j ti i t
4CRTM
1mm Gap
4CRTM
2mm Gap
SCRTM
1mm Gap
SCRTM
2mm Gap
observed near injection point and away from injection point
At 2 mm mold gap the ILSS properties of bidirectional laminates dropped slightly for the samples away from injection point if compared to close to injection point
© Fraunhofer ICT
p y j p p j p
SummaryThe CRTM process was investigated using 1 mm and 2 mm mold gap
The unidirectional ([0]4) and bidirectional ([0/90]s) laminate layup were used for
investigating the effect of chosen mold gaps on the CRTM process
The selection of 1 mm or 2 mm mold gap did not show any influence on the tensile and
flexural properties of the UD and bidirectional CRTM laminates
For bidirectional laminates at 1mm and 2 mm mold gap, depending on the degree of
mold filling after injection step, roving displacement and bad impregnation quality was
observed due to resin flow under compression force, solution reduction of resin
i itviscosity
CRTM process utilizes only the required amount of the resin which has a direct impact
on environment and process economyon environment and process economy
Due to very low resin injection time and impregnation time the CRTM process indicates
high potential for high volume manufacturing
© Fraunhofer ICT
high potential for high volume manufacturing
Outlook
Ongoing activities
Evaluation of different fabric architectures and fiber orientation on the CRTMEvaluation of different fabric architectures and fiber orientation on the CRTM
process development
Evaluation of effect of compression pressure on CRTM process developmentEvaluation of effect of compression pressure on CRTM process development
Use of highly reactive resins to manufacture laminates in less than 5 min cycle
time in the mould
Setting up automated Compression RTM infiltration setup using KraussMaffei
High Pressure RTM equipment for industrial scale manufacturing
© Fraunhofer ICT
OutlookOngoing activities
Development of the industrial scale High Pressure Compression RTM processp g p p
Prototype study:
Resin injection time: 7.5 sec
Impregnation time: 5-10 sec
Cure cycle time: 4 min
part size: 830x210x3 mmpart size: 830x210x3 mm
Fiber vol. content: ca. 57-60%
Prototype sample
© Fraunhofer ICT
Acknowledgement
"Dieses Vorhaben wird durch die Europäische Union - Europäischer Fonds für regionale
Entwicklung - sowie das Land Baden-Württemberg gefördert. Verwaltungsbehörde des
operationellen Programms RWB-EFRE ist das Ministerium für Ländlichen Raum,
E äh d V b h h B d Wü b W i I f iErnährung und Verbraucherschutz Baden-Württemberg. Weitere Informationen unter
www.rwb-efre.baden-württemberg.de“
© Fraunhofer ICT
Compression RTM - A new process for manufacturing p p ghigh volume continuous fiber reinforced composites
5th International CFK-Valley Stade Convention
07-08 June 2011, STADEUM Stade, Germany
Thank you very much for your kind attentionThank you very much for your kind attention.
Contact:
Raman ChaudhariRaman Chaudhari
Fraunhofer ICT
raman chaudhari@ict fraunhofer [email protected]