Insight into Re Verie autoclaved Composites By Simon

Insight into Re. Verie & autoclaved Composites By Simon Farren Presented at US Distributor Sector 111 11 th April 2009

History of Reverie Founded May 2000 by Simon Farren ex Lotus cars engineer on the management team for engineering the 340 R 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 Re. Verie. 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 @ Re. Verie 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-V 6 550 hp 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