Transcript Slide 1

Insight into ReVerie & autoclaved
Composites
By
Simon Farren
Presented at US Distributor Sector 111
11th April 2009
History of Reverie
Founded May 2000 by Simon Farren ex Lotus cars engineer on
the management team for engineering the 340R into production
realty.
Company founded to offer affordable autoclaved composites to
clients. We design and manufacture a range of quality parts for
track days and professional race team consumers through
worldwide dealers emphasising Lotus enhancing products.
What is Carbon Fibre?
• Carbon fibre is a synthetic thread (poly-acrylo-nitrile, rayon or pitch)
heated in an Argon atmosphere where carbonisation occurs.
• Carbonisation temperatures can be altered to produce different
strengths and modulus of the carbon fibre.
• The very fine carbon threads are left as long fibres along the roll
length (UD fibre) with strength in that axis only, or woven together
to form a fabric cloth resulting multi-directional strength.
• Carbon fibre can be left dry or pre-impregnated with a thermo set
resin to make it pre-preg.
• The cured resin gives the finished part its moulded shape, stiffness,
rigidity and protection of stressed fibres.
History Of Carbon Fiber
• First developed in 1958 by Dr. Roger Bacon in Cleveland, Ohio,
fibres were manufactured by heating strands of Rayon until they
carbonised. This process was inefficient. The resulting fibres
contained approximately 20% carbon, which resulted in less
strength and stiffness properties.
• Early in the 1960’s, a process developed using poly-acrylo-nitrile, as
a raw material. This produced a carbon fibre, which contained 55%
carbon, compared to 93-95% today.
• Early in 1969, Carr Reinforcements in
England first wove a carbon fibre fabric.
Why Composites?
• Carbon fibre is typically 3 X stronger than steel yet 4 X lighter.
• It’s 7 X stronger than 6061 alloy and 2 X stronger than tensile
modulus, with similar weight.
• Tensile modulus (stiffness) ranges from 230 Gpa to 441 Gpa and
tensile strengths range from 3.5 Gpa to 5.9 Gpa.
• The ultimate strength and the breaking strength are the same for
carbon fibre. Steel yields prior to reaching it’s ultimate strength.
• There is no yield to carbon fibre, so parts can be repaired with
lamination to the same shape easily.
• Kevlar has a yield strength 7 X higher than steel and about 4 X
lighter than steel. Bullet proof vests are manufactured with it.
Uses Of Composites
• Carbon fibre’s weight, stiffness and strength
benefits make it more widely used in boat
building, aerospace, motorsport and sporting
equipment.
• Other fibers like Kevlar, Dyneema and fiber
glass can be used solely or incorporated
into laminates.
• Resin systems are selected to give the required toughness,
temperature range & protect the stressed fibres from damage.
• Modulus & strengths of fibres, thickness and direction of fibres can
be varied to give the properties required for the part.
Autoclave Processing Pre-Pregs
We extensively use thermo set epoxy pre-preg fibres at ReVerie.
We process using one of two pressurised & temperature computer
controlled autoclaves, which are used by Formula One teams.
The use of elevated pressure in the autoclave facilitates a high
fibre volume fraction and low void content for maximum
structural efficiency.
Autoclave Processing Pre-Pregs
The UD pre-preg fibre or woven cloth is hand cut or done by
machine into the shapes and the orientation required for each ply
of the component, which form the kit of parts.
Autoclave Processing Pre-Pregs
Each section of a ply is hand placed into the female mould or over
the male mould in the orientations required by the drawing.
Autoclave Processing Pre-Pregs
Some components (due to under cuts or necessity to get a complex
vacuum bag inside) require the moulds to be multi-pieced and
overlapping joints in the pre-preg are often required.
Autoclave Processing Pre-Pregs
A mould tool, either male or female, is required to obtain a good
surface finish on one side. Both a male and female compression
tool is needed for a dual moulded surface.
The tool has a release agent applied
to it’s surface to avoid sticking.
Autoclave Processing Pre-Pregs
Once lay-up is complete, a layer of thin release film (approx 15
microns) is applied over the surface of the pre-preg, where the
vacuum bag may make contact. This allows the breather layer or
bag to release from the cured composite surfaces.
Autoclave Processing Pre-Pregs
A polyester breather fabric layer is then applied to the outside of
the mould and where possible across the component surface. The
purpose of this fabric is to allow a full vacuum path over the
complete mould and component area.
Autoclave Processing Pre-Pregs
Vacuum bags are applied. They can be a single sheet sealed with
tacky tape against the mould’s outer perimeter on a simple male or
female tool or a tubular envelope bag sealed at both ends to
vacuum the complete perimeter of the mould tool. Any internal
tubular bags or moulded latex bladders can be left out of one or
both ends of the tubular bag. A vacuum breach fitting goes through
the bag surface to allow air to be removed.
Autoclave Processing Pre-Pregs
The air is slowly sucked out by a very powerful vacuum pump down
to 5 Torr. The pre-preg resin matrix layers are forced together onto
the mould surface at nearly one atmosphere (14.7 psi approx). As
the air is removed the vacuum bag is carefully manipulated to
ensure it does not stretch too tightly over features.
Autoclave Processing Pre-Pregs
The component is under full vacuum, any internal tubes or bladders
open to atmosphere will be exerting 14.7 psi pressure internally.
The mould is now ready for its thermo set process either in an oven
to cure at 14.7 psi or in an autoclave to cure at up to 100 psi. The
greater the pressure the lower the void content and the higher the
strength and greater surface finish.
Autoclave Processing Pre-Pregs
Once in the autoclave the vacuum bag is connected to a vacuum
line, a steel wire reinforced line which will not collapse under
pressure. Once the autoclave reaches 14.7 psi the vacuum circuit
externally can be vented to atmosphere or left connected to
remove volatiles. Most of our component pre-pregs cycle at
temperature for 90 minutes at 120°c.
The pressure used depends on the quality of the mould and if the
component is monolithic or
features a core material such
as foam or honeycomb.
Autoclave Processing Pre-Pregs
Once the cure has finished the mould and component are left to
cool and then are removed. The bagging film is removed and the
mould unbolted, if multi sectioned. The component is carefully
released with plastic wedges. The component is now ready to be
trimmed to size, secondary bonded and polished or sanded for
paint.
Product Design @ Reverie
Identifying a market niche for a new product, either from
customers, dealer feedback, demand or via our own research.
Each product design is optimised for shape within constraints of
packaging and aerodynamic performance and material selection by
experience or where required mathematical analysis using either
hand calculations or computerised FEA.
Passionate about improvements
Product Design @ Reverie
Products are designed on CAD where packaging requirements and
draft angles can be checked and amended before machining.
Sometimes products are prototyped up and tested at low cost to
prove design performance or shape (results factored into future
design enhancements).
Design to Production @ ReVerie
Male patterns from foam or clay are either handmade or CNC
machined from CAD data out of aluminium block or solid epoxy
tooling slabs, which are bonded together to form the cubic block.
Design to Production @ Reverie
Once a male pattern is available, any split lines required for
undercuts can be defined by removable weir walls at 90˚ to the
surface featuring dowel location holes to ensure alignment.
A mould tool can then be hand laid from the pattern with weirs in
carbon fiber and autoclave cured .
For low volume projects sometimes a high temperature GRP hand
laminated tool is produced.
Tools can also be machined direct from alloy.
A layup drawing is then produced
for the laminating shop.
Recent Product Developments
Supercharged Rst-V6 550hp Evo Rear Wing, Diffuser, Floor, Splitter
Reverie In High End Motorsport
WRC
WSB
FIA GT
AMLS
Why Choose a Reverie Part
• Established reputation for high quality
• Excellent design and product testing
• Autoclaved manufacturing ensuring
high fibre to resin ratio and very low voids
• Manufacturing controlled on-site
• Use the highest quality Cytec pre-preg materials
• Excellent customer service, technical data and help
• Chosen by some of the best engine builders and race teams
• Passionate about continuous and constant improvements and
enhancements