VACUUM / AUTOCLAVEAutoclave technology for producing composite elements achieves laminates with mechanical features much higher than the more traditional and economical technologies analysed to date. Using an autoclave will intensify the debulking action by increasing pressure to 7-10 atm and the temperature up to 200 °C during the cure cycle. Our autoclaves also provide the possibility to change pressure and temperature during the curing cycle by means of time, temperature and pressure control programs based on the particular type of resin involved. Higher pressure means no trapped air between the layers, which with other technologies reaches or exceeds 65%, the maximum tolerance in manufacturing composites. This type of manufacturing is used for making parts with extreme mechanical features, for example those required by the aeronautics, space and medical industries.
Prepreg lay-up consists of manually depositing unidirectional pre-impregnated fibers (UD), fabric and multi-axial fibers onto open shell and/or composite moulds for producing complex shapes unobtainable with other technologies.
The different layers of prepreg material with the characteristics specified for the part to be made, such as type of fiber, percentage of resin, fiber basis weight and orientation, are cut to the required size and shape by a CNC plotter. The different layers of prepreg are applied by wrapping onto the mould in a specific order (PLY BOOK), according to the plans drawn up to achieve the necessary mechanical requisites.
At the end of the process for depositing prepregs on the mould, release film and breathers/bleeders are applied to the lamination to be placed into a vacuum bag which is closed with sealant tape. A vac valve is fitted to the bag and a vacuum pump sucks the air out with the aid of the breather/bleeder.
When this operation is performed by skilled engineers it makes the bag adhere perfectly to the laminate, compressing it onto the mould (if the laminate is very thick perfect debulking is achieved by repeating this operation a number of times before going on to the autoclave). The next step is placing the moulds into the autoclave and connecting them to its vacuum circuit. The cure cycle is set up with a special program to run the time, temperature and pressure functions. A pressure of 7-10 atm in the autoclave then compresses the material in contact with the mould and the vacuum in the bag will remove any trapped air and residual solvents to produce an object with features not possible with other technologies.
Furthermore, the freedom provided by this process to produce any type of shape and the possibility to insert local reinforcement into the lay-ups at isostatic pressure points to resist load lines more effectively, optimize the highly resistant structural capacity of components, unobtainable in any other way.