Manufacturing Processes of Composite Structures Ing. Bohuslav Cabrnoch, Ph.D. VZLÚ, a.s.
Manufacturing Processes of Composite Structures
Ing. Bohuslav Cabrnoch, Ph.D.
VZLÚ, a.s.
Manufacturing Processes
Manufacturing processes
Wet lay-up
Prepregs
Resin Film Infusion (RFI)
Resin Transfer Molding (RTM)
Vacuum Infusion Process (VIP)
Filament Winding
Braiding
Sheet Moulding Compound (SMC)
Pultrusion
Wet Lay-up
Wet Lay-up
Dry reinforcement impregnated by catalyzed resin Impregnation by roller, brush or spatula Open mould method With or without vacuum compaction Curing at RT Optional post-curing in oven at elevated temperature (usually up to 80°C) Mats, fabrics, gel coat
Wet Lay-up
Gel coat
Surface layer at thickness about 0,5 mm
Pigmented resin (usually UP or EP)
Application by brush, spray
reasons for application
To provide a high-quality finish on the visible surface
To increase lifetime (wearing resistance)
Protective coat against environment (moisture, UV, chemicals)
Prepreg
Prepreg process
Prepreg (pre-impregnated) Reinforcement is already impregnated by matrix resin Requires cold storage (-18°C) to prevent complete curing Limited lifetime Precise fiber volume fraction
Semipreg Reinforcement is already impregnated by film matrix resin
from one side only
Impregnation machine Solvent (solution of resin and solvent)
Hot-melt
Prepreg General manufacturing process Mould preparation
Cleaning, application of release agent
Prepreg cutting Cutting of prepreg layers
Lay-up Temperature, humidity, dustiness
Vacuum bagging Peel ply, release film, breather mat Vacuum bag
Expendable Reusable
Curing Temperature, time, pressure, vacuum
Removing of cured part from mould
Prepreg
Prepreg cutting
Requirements – Precision
– No prepreg contamination
– Marking
Techniques – Tangential knife
– Oscillating knife
– Water jet
Prepreg
Hand lay-up
Requirements – Precision (position, orientation)
– No prepreg contamination
– Elimination of entrapped air
Equipment – Clean Room
– Positioning means
• Gauges / Templates
• Laser projector
Prepreg
Automated lay-up Higher effectivity than hand lay-up
Hand lay-up 0,5 – 1 kg/h
Automated about 10 kg/h
ATL (Automated Tape Laying)
Laying of UD and fabric prepregs and film materials in 3 – 305 mm bandwidths
Big flat parts
Laying, trimming and debulking at once
AFP (Automated Fiber Placement)
Laying of single strands (tow-preg) or Slit tapes (3,2 ÷ 12,7 mm widths)
Small or complex surfaces
Prepreg Vacuum bag materials
Prepreg
Curing
Curing cycle – Temperature – Pressure – Vacuum – Time
Prepreg
Autoclave curing
Přetlak p1
Podtlak p2
1
4
6
5
3
2
Autoclave
Vacuum bag
Trolley
Breather mat
Curing part
Mould
Vacuum
Pressure
Prepreg
Autoclave curing
Heating /
cooling
Autoclave
Air
circulation
Mould
Resin Film Infusion
Resin Film Infusion (RFI)
Impregnation of dry reinforcement by resin film
SPRINT® (SP Systems / Gurit)
LF Technology (5M)
ZPREG® (ACG / Umeco / Cytec)
Resin Film Infusion
Resin Film Infusion (RFI) Comparison with prepregs
Possibility to set fiber volume fraction Simpler logistic – only one type of resin Lower storage requirements - only resin stored in freezer
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Vacuum Infusion Process (VIP)
Impregnation of dry reinforcement in single open mould under a bag Resin injected by vacuum only 50 ÷ 1000 parts / mould / year
Gelcoat Resin supply
Vacuum Vacuum bag
Distribution layer
Part lay-up
Mould
Bleeders
Vacuum distribution/
resin capture
Sealant tape
Infusion Processes
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Resin Transfer Moulding Light (RTM Light )
Impregnation of dry reinforcement in close mould
Back side mould is transparent laminate usually
Resin injected by vacuum only or under low pressure
50 ÷ 1 500 parts / mould / year
Gelcoat
Resin supply
Vacuum
Back side mould Supporting frame
Part lay-up
Mould
Sealant
Infusion Processes
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Resin Transfer Moulding (RTM) Impregnation of dry reinforcement in stiff close mould
Resin injected under pressure 0,2 – 1,0 MPa
Stiff and heavy moulds
500 ÷ 5 000 parts / mould / year
Gelcoat
Resin supply Vacuum Plug Heating
Part lay-up
Cavity
Infusion Processes
Vacuum Infusion Processes Alternative of VIP
CIRTM co-injection RTM Crystic VI vacuum infusion (Scott Bader) DRDF double RIFT diaphragm forming (University of Warwick) LRI liquid resin infusion MVI modified vacuum infusion (Airbus) Quickstep use of liquids for enhanced heat transfer in infusion RIFT resin infusion under flexible tooling (ACMC Plymouth) RIRM resin injection recirculation moulding SCRIMP Seeman Composites Resin Infusion Molding Process VAIM vacuum-assisted injection moulding VAP vacuum assisted processing (patented by EADS) VARI vacuum assisted resin injection system (Lotus Cars) VARIM vacuum assisted resin injection moulding V(A)RTM vacuum (-assisted) resin transfer moulding VIM vacuum infusion moulding. VIMP vacuum infusion moulding process VM/RTM Light a hybrid RIFT/RTM (Plastech)
Filament Winding
Filament Winding
Laying of impregnated yarn on rotating mandrel / liner
Circular and non-circular cross-sections
Shafts, pressure vessels
Filament Winding
Filament Winding
Helical pattern winding
Polar method
Braiding Braiding
Dry preform manufacturing
Impregnated by infusion processes
Circular and non-circular cross-sections
SMC (Sheet Moulding Compound) Prepreg sheets cured into matched metal dies under heat and pressure
Prepregs SMC - R – chopped fibers - CR – continuous + chopped fibers - XMC – continuous reinforcement
UP or VE resin
Sheet Moulding Compound
Pultrusion
Pultrusion
Pultrusion is an automated process used to create
shapes by pulling rovings through a shaped and
heated die
Manufacturing Processes
Comparison of manufacturing processes according to achievable fiber volume fraction
Process Fibre Volume Fraction [%]
Wet Lay-up 10 – 38
Prepreg 50 – 70
RFI 45 - 60
RTM 25 – 65
VIP 25 –50
Braiding 25 – 65
Filament Winding 45 - 65
Pultrusion 43 - 83
Thermoplastics
Manufacturing of thermoplastic composites
Press forming
Matched metal dies
Elastomeric tool
Autoclave
Vacuum forming
Thermoplastics
Press forming
Thermoplastics
Press forming – typical parts
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Moulds
Requirements Temperature resistance
Dimensional stability
Lifetime
Thermal expansion
Materials Metallic
– Al alloys – Steel – Invar – Electroforming
Non-metallic
– Wood MDF (Medium Density Fibreboard)
Matchboard
Tooling
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Moulds
Materials Non-metallic
– Block materials EPS, XPS
PUR
EP
– Composite Glass, Carbon fibers
UP, EP
Wet lay-up, prepreg, spray-up
Gelcoat
Tooling
Tooling
Moulds
Single open moulds
Pressure bag moulding
Autonomy heated moulds
Tooling
p
1
2
3
Curing oven
Curing part
Pressure bag moulding
Pressure bag moulding
Curing pressure is induced by flexible bag
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Master models (Plugs)
Requirements Temperature resistance
Dimensional stability
Thermal expansion
Materials Block materials
– EPS, XPS – PUR – Axson, Ebalta, OBO, Rampf, Necuron
Model pastes
MDF (Medium Density Fibreboard)
Matchboard
Tooling
Machining
Machining
Conventional Water Jet
Machining
Conventional machining
Tooling materials – HSS (coatings) – Carbide (coatings) – Polycrystalline Diamond (PCD)
• Inserts
Manual – Pneumatic and electric tools
• Guides / Templates • Trimming fixtures
– Dustiness – dust exhaust • Carbon - explosive
atmosphere
Machine – CNC mills – Robot platforms
Machining
Conventional machining - contour
Straight edges Diamond saw blades
Complex shape edges End mills
Reciprocal saw
Machining
Conventional machining - holes
Tooling materials
Carbide
Polycrystalline Diamond (PCD) - inserts
Drilling
Milling
Countersinking
Machining
Conventional machining - holes
Standard drill bits – delamination
Special geometry of tool face
8 Facet drill
Kevlar drill
Reamer drill
Dagger drill
Precise holes
Reamers
Machining Honeycomb machining
Expanded
High speed spindles
Ultrasound
Non-expanded blocks
Band / circular saw
Milling
Machining Honeycomb machining– high speed spindle
Complex shapes
Chamfering / Cut-outs Limitation by tool shape
Sandwich panels
Machining
Honeycomb machining– high speed spindle
Tools
Roughing cut
Finishing cut
Materials
HSS
Carbides
Coated Carbides
Diamond
Machining
Honeycomb machining – ultrasound
Oscillating knife
Frequency 20 kHz
Cut-offs, chamfering
Sharp edges
Machining
Water jet
CNC machines
Robot platforms
A mixture of water and an abrasive substance
No heat-affected zone
Dust free, no fumes
Low cutting forces