Insight into Reverie

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Insight into Reverie autoclaved
compositesBySimon FarrenPresented at US
Distributor Sector 111 11th April 2009
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History of Reverie

• Founded in May of 2000 by Simon Farren,
  previously on the management team for engineering
  the Lotus 340R into a production reality.
• Created to offer affordable autoclaved
  composites to clients. We design and manufacture
  a range of quality parts for track days and
  professional race team consumers for distribution
  via worldwide dealers emphasizing Lotus enhancing
  products.

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What is Carbon Fiber?

• Carbon fiber is a synthetic thread
  (poly-acrylo-nitrile, rayon or pitch) heated in
  an argon atmosphere where carbonization occurs.
• Carbonization temperatures can be altered to
  produce different strengths and modulus of the
  carbon fiber.
• The very fine carbon threads are left as long
  fibers along the roll length (UD fiber) with
  strength in that axis only or woven together to
  form a fabric cloth resulting multi-directional
  strength.
• Carbon fiber can be left dry or pre-impregnated
  with a thermoset resin to make it pre-preg.
• The cured resin gives the finished part its
  molded shape, stiffness, rigidity and protection
  of the stressed fibers.

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History Of Carbon Fiber

• First developed in 1958 by Dr. Roger Bacon in
  Cleveland, Ohio,fibers were manufactured by
  heating strands of Rayon until they carbonized.
  This process was inefficient. The resulting
  fibers contained approximately 20 carbon, which
  resulted in less strength and stiffness
  properties.
• Early in the 1960s, a process was developed
  using poly-acrylo-nitrile, as a raw material.
  This produced a carbon fiber, containing55
  carbon, compared to 93-95 today.
• Early in 1969, Carr Reinforcements in
• England first wove a carbon fiber fabric.

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Why Composites?

• Carbon fiber is typically 3 X stronger than steel
  yet 4 X lighter.
• Its 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 fiber. Steel yields
  prior to reaching its ultimate strength.
• There is no yield to carbon fiber, 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.

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Uses Of Composites

• Carbon fibers weight, stiffness and strength
  benefits make it widely used in boat building,
  aerospace, motorsport and sporting goods.
• Other fibers like Kevlar, Dyneema and fiberglass
• can be used independently or incorporated
• into laminates.
• Resin systems are selected to give the required
  toughness, temperature range protect the
  stressed fibers from damage.
• Modulus strengths of fibers, thickness and
  direction of fibers can be varied to give the
  properties required for the part.

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Autoclave Processing Pre-Pregs

• We process thermoset epoxy pre-pregs using one
  of two pressurized temperature computer
  controlled autoclaves, which are used by Formula
  One teams.
• The use of elevated pressure in the autoclave
  facilitates a high fiber volume fraction and low
  void content for maximum strength.

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Autoclave Processing Pre-Pregs

• The UD pre-preg fiber or woven cloth is hand cut
  or done by machine into the shapes and
  orientation required for each ply of the
  component, which form the kit of parts.

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Autoclave Processing Pre-Pregs

• A mold 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 molded surface.
• First the tool has a release agent applied to
  its surface to avoid sticking.

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Autoclave Processing Pre-Pregs

• Each section of a ply is hand placed into the
  female mold or over the male mold in the
  orientations required by the drawing.

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Autoclave Processing Pre-Pregs

• Some components require the molds to be
  multi-pieced and overlapping joints in the
  pre-preg are often required.

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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.

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Autoclave Processing Pre-Pregs

• A polyester breather fabric layer is then
  applied to the outside of the mold and where
  possible across the component surface. The
  purpose of this fabric is to allow a full vacuum
  path over the complete mold and component area.

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Autoclave Processing Pre-Pregs

• Vacuum bags are applied. They can be a single
  sheet sealed with tacky tape against the molds
  outer perimeter on a male or female tool or a
  tubular envelope bag sealed at both ends to
  vacuum the complete perimeter of the mold tool.
  Any internal tubular bags or molded 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.

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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 mold
  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.

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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 mold
  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.

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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 can be externally vented to
  atmosphere or left connected to remove volatiles.
  Most of our component pre-pregs cycle at
  temperature for 90 minutes at 120c or 248f.
• The pressure used depends on the quality of the
  mold, if the component is monolithic or features
  a core material such as foam or honeycomb.

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Autoclave Processing Pre-Pregs

• Once the cure has finished, the mold and
  component are left to cool. The bagging film is
  removed and the mold 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.

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Product Design _at_ Reverie

• Identifying a market niche for a new product,
  either from customers, dealer feedback, demand
  or via our own research.
• Each product design is optimized for
  strength/weight and shaped within constraints of
  packaging and aerodynamic performance. Materials
  selected by experience, or where required by
  mathematical analysis using either hand
  calculations or computerized FEA.
• Passionate about improvements

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Product Design _at_ Reverie

• Products are designed on CAD where packaging
  requirements and draft angles can be checked and
  amended before machining.
• Products are prototyped and tested at low cost
  to prove design performance these results are
  factored into future design enhancements.

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Design to Production _at_ 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.

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Design to Production _at_ 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 mold 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.

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Reverie In High End Motorsport
WRC WSB FIA GT AMLS
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Why Choose a Reverie Part?

• Established reputation for high quality.
• Exceptional design and product testing.
• Autoclaved manufacturing ensuring
• high fiber 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.