between plies, giving a cost- effective laminate scheme that allows for rapid layup by reducing processing times and labour content. From Tier 2 to Tier 1 Having supplied material as a Tier 2 supplier on niche vehicle projects such as the Rover MG SV, Gurit took the decision to invest in a pilot facility and manufacture SPRINT CBS components as a Tier 1 supplier. Prior to this decision by Gurit, the development project ALBOS ( Advanced Lightweight Body Structures) - run in conjunction with Aston Martin Lagonda Ltd - lead to the company securing the production of the fenders, hood and deck- lid assemblies on the DBS. The challenge then was to productionise the technology from previously short series, low volume processing - vacuum bagged, oven cured parts in pre- preg tooling - to a robust and cost- effective process for major premium vehicle OEM build rates. Gurit's approach to part manufacture was to avoid traditional oven or autoclave batch curing processes that rely on optimising facility usage rates for productivity. The varied complexity of the parts and the corresponding variation layup times would create a situation where the less complex parts would be loaded for cure whilst the more complex parts would be at layup or bagging stages. The solution to avoiding moulding batch issues was to specify standalone nickel shell tools, which are heated individually. Heating and cooling are provided from a central boiler and chiller unit that pipes oil to a number of mould stations. Moulds are connected to the heating system via dry connectors, allowing tools to be disconnected and moved freely. The relative low mass and direct heating and cooling system of the tools allows for component cure cycles to be in the region of 60 minutes from start to de- mould with a 30 minute dwell above 130° C. The standalone nature of the tooling allows cures for each component to be run independently and eliminates the lost time that components would spend in WIP being held under vacuum whilst waiting for oven or autoclave cure. With a suitable tooling and moulding scheme identified, the next step was to develop a cost- effective method of consolidating the components during cure. Two main criteria were established; to reduce or eliminate,
where possible, the use of consumables, and to aid the integration of components into bonded assemblies, a tooled B- surface. Towards the finished product The final solution for production uses a lightweight glass SPRINT B-tool to define the B- surface of the part. B- tools are laid up and cured on a resin infused master tool, master tools having been infused ( in house) on a machined epoxy tooling block. Using this system vacuum bagging time is reduced - typically 30 minutes for each component. The next step in optimising the process for production was to increase the throughput of each tool by reducing layup time, thereby increasing the proportion of time the tool is adding value i. e. curing. Each production mould has an accompanying pre- form tool. Laminates are laid up during the cure of the previous part, and once this has been de- moulded, the preform is transferred from the preform tool to the production mould. Pre- forming reduces the layup time by up to two thirds. In conclusion, Gurit believes that composites, specifically long fibre reinforced thermosets, can compete with the more established body closure technologies. Using SPRINT CBS and SPRINT surface film results in a high- quality class- A finish with dramatically reduced weight versus a metal or even an all carbon composite panel. Gurit's holistic approach to the challenges, in formulation, laminate architecture and processing is necessary to provide OEMs with cost effective solutions they require. more information? click here!