Resin Infusionunder Flexible Tooling

(RIFT)

John SummerscalesAdvanced Composites Manufacturing CentreSchool of Marine Science and Engineering -

University of PlymouthPlymouth, PL4 8AA, United Kingdom

Outline of presentation

• other manufacturing processes• four variants on resin infusion

– advantages and disadvantages– applications using the process

• notional cost comparisons• brief summary

Manufacturing processes

• spray• hand lamination• hot press• Resin Transfer Moulding (RTM)• Resin Infusion under Flexible Tooling

(RIFT)• vacuum bagging and autoclave cure• filament winding• pultrusion

Manufacturing processes

• Resin transfer moulding (RTM)– long-range flow of resin into a dry fibre

pack preloaded into a defined mould cavity.

• Resin infusion (RIFT)– A range of intermediate techniques

• Vacuum bagging and autoclave cure– wet resin or prepreg lamination followed

by bagging and cure under pressure

Change from hand lay-up ?

• Increased consolidation pressure– 1 atmosphere = full vacuum = 105 N/m2 (10 tonnes/m2)

• Occupational Exposure Levels– Germany/Sweden20 ppm– France/Spain 50 ppm– United Kingdom 100 ppm– EU harmonisation via SPA recommendation for end

2013

• Pollution Prevention and Control Act 1999– styrene has an odour threshold of 0.034 ppm

i.e 630 µg/m3

Why resin infusion ?

• Resin transfer moulding (RTM)– as mouldings increase in size,

mould clamping forces become excessive

• Vacuum bagging and autoclave cure– premium price for

pre-impregnation of reinforcements– long cycle times– capital cost of equipment

Resin infusion

• Muskat patent application, 1945– the fibrous base to be impregnated …

preferably in a substantially dry state – drive the resin into the base to impregnate it – one tube being connected to a source of resin

and the other to a vacuum pump – complementary moulds appear to be free to

move together under vacuum

• process introduced to UK by Scott Bader in 1946

“Acronym” anarchy !• 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• RFI: resin film infusion• RIFT: resin infusion under flexible tooling (ACMC Plymouth)• RIRM: resin injection recirculation moulding• SCRIMP Seeman Composites Resin Infusion Molding Process (TPI) • 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)• VIP: vacuum infusion process

Resin infusion

• RTM with one tool face replaced by a flexible film or a light splash tool

• flow of resin results only from vacuum and gravity effects

• mould cavity varies with local pressure

• thickness of the part depends onpressure history

Resin Infusion underFlexible Tooling (RIFT 1 of 4)

• Basic RIFT process:– resin flows in the plane of the fabric

between the mould and the bag

– slow process due to limited pressure gradient– Only good for

• low fibre volume fraction/high loft fabrics• reinforcement with flow enhancement tows

Resin feed

Vacuum

KEY

Reinforcement

RIFT 1:slow flow in the processSpecial fabrics• Commercial process needs flow-enhancing tows, e.g.

– Brochier Injectex

– Carbon fabrics from Carr Reinforcements

– Glass fabrics experimental programme with Interglas-Technologies

Potential advantages Process

• use most resin systems.

• use most forms of reinforcement fabrics.

• large structural components can be fabricated.

• relatively low tooling costs for high-performance components.

• better than wet-laid components with little modification of tooling.

• heavy fabrics more easily wetted than by hand lamination.

• lower material costs than for prepreg and vacuum bagging.

Potential advantages

Performance

• higher fibre volume fraction gives improved mechanical performance.

• minimal void content relative to hand lamination.

• more uniform microstructure than hand lay-up.

• cored structures can be produced in a single flow process.hand-lamination resin infusion

Disadvantages

Process

• complex process requires different skills to hand-lamination.

• emphasis on preparation, not on the actual moulding process.

• sensitive to leaks (air paths) in the mould tool and the bag.

• quality control of the resin mixing is "in-house".

• slow resin flow through densely packed fibre

• uneven flow could result in unimpregnated areas/scrap parts.

• not easily implemented for honeycomb core laminates.

Disadvantages

Performance

• only one moulded surface

• low resin viscosity means lower thermal and mechanical properties.

• thinner components have lower structural moduli

• laminate thickness dependent on flow history (next slide)

• licensing costs where aspects of the process patented in the USA

Fabric compressibility in RIFT

• A B C

2.2 mm

2.0 mm

1.8 mm 0 2000 4000 Time (s) 7500 11500

• nine layers of plain weave E-glass/UPE resin• compression by vacuum• lubrication by resin front at A• relaxation as pressure gradient falls• resin inlet closed at C

Comparison of HL and RI resinsSP resin systems hand lamination infusion

Ampreg 20 Prime 20Property UnitsViscosity mPa.s 447 188Tg (50C post-cure) °C 85 86Tensile strength MPa 83 74

RIFT vacuum forming

• Known as – DRDF: Double RIFT Diaphragm Forming, or– RIDFT: Resin Infusion between

Double Flexible Tooling

• dry fabric is placed betweentwo elastomeric membranes;

• resin is infused into the fabric;• the ‘sandwich’ is vacuum-formed

over the mould shape.

RIFT vacuum formingNB: an alternative RIFT I route to complex shapes

RIDFT image from JR Thagard, PhD thesis,Florida State University, 2003.

RIFT with flow mediumRIFT 2 of 4• A high permeability fabric

allows resin to flood one surfacefollowed by through-thickness flow

• commonly referred to as either:– V(A)RTM

• Vacuum (assisted) resin transfer moulding

– SCRIMPTM

• Seeman Composites Resin Infusion Manufacturing Process• patented in the USA but prior-art exists in Europe

Resin feed

Vacuum

KEY

Flow medium

Reinforcement

EADS VAP® process

Membrane = Gore Composite Manufacturing Membrane (GCM)

Image reproduced with permission from EADS

2m diameter CFRP sonar dome

• non-crimp carbon fibre fabric monolithic composite

• from 9 mm to 50 mm thick, Vf = 60%, Vv = negligible

CFRP catamaran forward beam60v/o NCF (6000 x 300 x 50 mm)

Manufactured by Julian Spooner

Channel section to form box with a second joggled moulding - integral top hat supports Web: 600gsm triax / 9mm balsa /

600gsm carbon triaxFlanges: 600gsm triax / 4mm UD / 600gsm triaxSicomin SR8100 resin system Layup: 7 man hours,Infusion: 25 minutes,  20ºC / 20mBPostcure: 10h @ 50ºC

Manufactured by theSCRIMPTM process

J-boats Poma-Otis mass transit

Images from www.tpicomp.com

Reitnouer flat bed trailer NABI 30-foot bus

Benefits of SCRIMPTM

• Vosper Thornycroft state: • resin infusion into tows is independent of fabric weight.• reduced costs and greater efficiency in production:

fewer layers of heavier fabriccompared to 35 separate plies of 800 gsm woven roving glass used in hand lamination.

• reduced component weight (up to 72% fibre by weight).• void content down from 5% by HL to <1% by SCRIMPTM.• increased laminate strength

due to the higher fibre fraction and reduced void content.

• reduced styrene emissions and waste resin.

The NEG-Micon40 m radius AL40 carbon-wood epoxy wind turbine blade

Resin infusion manufacturing process developed with ACMC

Advanced Composite Armoured Vehicle Platform (ACAVP)

• demonstrator manufactured by “VARTM”• reinforcement is quasi-isotropic

non-crimp E-glass fabric• bare hull weight is around 6000 kg

Image from http://www.janes.com/defence/land_forces/news/jdw/jdw010312_3_n.shtml

Civil engineering structures• DML Composites rehabilitate

fractured structures for London Underground

CFRP infusionvs welded steel repair

• London underground– ~£40K/day lost revenue

for closing the line between two stations

• Offshore exploration and exploitation– ~£500K/day of crude oil through small

platform– need to drain down before hot work

(welding)!

Resin Film Infusion (RFI)RIFT 3 of 4• B-stage “prepreg” resin film without

fibres• interleaved with reinforcement

or grouped film layers in dry laminate

• unlike prepreg, there are air channels within the bagged laminate

Vacuum

KEY

Resin film

Reinforcement

RFI (RIFT 3) for aerospace

• T-beams, aileron skin, swaged wing rib, three-bay box– Kruckenberg et al , SAMPE J, 2001

• fuselage skin panel for the Boeing 767 aircraft was moulded as a demonstrator with integral stiffeners– Cytec 5250-4RTM bismaleimide resin (100 mPa.s at 100°C)– 880 x 780 mm woven 5-axis 3-D fabric preform– Uchida et al , SAMPE J, 2001

• fuselage panels in TANGO Technology Application to the Near-term business Goals and Objectives of the aerospace industry– skins will be non-crimp fabric preforms– integrated stringers to be triaxial braids with unidirectional

fibres– Fiedler et al, SAMPE J, 2003

“Semi-preg” infusionRIFT 4 of 4• fabric partially pre-impregnated with resin

• Commercial systems include– Cytec Carboform

• resin impregnated random mat between the two fabric layers

– Hexcel Composites HexFITTM

• film of prepreg resin combined with dry reinforcements

– SP Systems SPRINT®: SP Resin Infusion New Technology• resin between two fabric layers

– Umeco (ACG) ZPREG• resin stripes on one side of fabric

Vacuum

KEY

Resin stripes

Reinforcement

Comparisons ( debateable! )

In-planeFlow

mediumRFI Semi-preg

Material costs

Consumables

Process time

Quality

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Summary

• reviewed the four major variants of the Resin Infusion under Flexible Tooling process.

• considered the application of these techniques to the manufacture of large composite structures.

• recommend this route for the manufacture of large composite structures.

ACKNOWLEDGEMENTS

• Higher Education Funding Council of England (HEFCE) Development of Research for funding early research into resin infusion

• Christopher Williams and Jim Craen for their respective contributions to the project.

• David Cripps at SP Systems Limited for most helpful discussions of an earlier version of this paper.

• Paul Hill at DML Composites for permission to use his Figure.

• Use of trade names/trade marks in the text of this chapter does not imply endorsement by the authors of any specific product. Such descriptions are provided simply in the interest of traceability.

PublicationThe content this presentation has been

refereed and is published asJohn Summerscales and TJ Searle

Low pressure (vacuum infusion) techniques for moulding large composite structures

in Proceedings of the Institution of Mechanical Engineers Part L - Journal of Materials: Design and Applications, February 2005, L219(1), 45-58 .

Based on earlier PowerPoint

previously presented at:• Universiti Putra Malaysia, Bangi, Sept 2004• Imperial College London, Dec 2004• SAMPE out-of-autoclave symposium, Feb 2005• Forum for Plastkompositter – Norway, Nov 2005• Composite Innovations – Barcelona, Oct 2007• ICMAC – Belfast, March 2009• RINA – London, February 2010• SWCG – Plymouth, September 2012.

.. to contact me

Dr John Summerscales jsummerscales@plymouth.ac.uk http://www.plymouth.ac.uk/staff/jsummerscales

School of Engineering Reynolds Building RYB 008 University of Plymouth Devon PL4 8AA England

01752.5.86150 01752.5.86101