22 April 2004
22 April 2004
Airtech AMG have expanded their broad Toolmaster range of composite tooling materials with the introduction of Toolfusion.
Epoxy resins specifically formulated for the tooling application have been developed with low viscosity allowing tools to be manufactured with the resin infusion process. Fibreglass and graphite fabrics have been combined with all the vacuum bagging materials and processing equipment to provide all materials from the same catalogue.
Dry cloth placed on the mastermodel is then vacuum bagged. Resin lines are inserted for resin flow into the cloth and also for vacuum application through a vacuum pot to trap resin before it reaches the vacuum source. The pressure difference between the resin bucket and vacuum pot then draws the epoxy resin into the dry fabric quickly achieving full fabric wet out.
The Toolfusion range offers room temperature curing with Toolfusion 1 resin, which can then be post cured up to a final use temperature of 191°C. Alternatively, Toolfusion 2 resin offers 204°C post cure after an initial cure at 60°C. Neither system requires autoclave pressures, therefore reducing the energy cost in any tool manufacture.
Toolfusion resins can be stored at room temperature, potentially reducing refrigeration costs during shipping and storage. This also means there are no outlife restrictions requiring tools to be laminated quickly to avoid pre-preg partially curing. Laminations of fabrics can therefore be done at various speeds avoiding the need for crowding the master model with laminators and expensive labour overtime.
Unlike the hand laminating process this is a cleaner manufacturing process. Resin exposure is minimal as the fabrics are wet out under a vacuum bag using the pressure difference of applied vacuum. Fabric positioning is done in the absence of resin, again at your own speed ensuring good positioning to avoid corner bridging and conformation to shape.
Room Temperature curing of Toolfusion1 and low temperature curing of Toolfusion2 reduce the demands on temperature performance of mastermodels, which may mean lower costs for tool manufacture. This also extends the opportunities for reverse engineering, allowing tools to be taken from components with now exposure to potentially damaging elevated temperatures. Mastermodels or components for reverse engineering must only hold good shape and good vacuum. Expensive tooling blocks can now be substituted with lower cost boards or foam for CNC machining. Other techniques such as traditional hand carved patterns, GRP skinned plywood plugs can further reduce cost and increase mastermodel options.
Infusioncoat resin is a non-sagging surface resin specifically developed for use with the Toolfusion1 system. This offers dual benefits of eliminating the need for fabrics tacifiers to hold the first ply on the mastermodel, often resulting in minor defects in the tool surface and producing a hard surface finish on the cured tool surface.
Fibreglass and Graphite Fabrics offered in the Toolfusion range have been developed to ensure predictable and complete resin dispersion and wet-out during the infusion process along with ease of handling and positioning during the laminating stage of manufacture. A variety of fabric styles, including plain weave , 2 x 2 twill and 4HS weave are available.
Dry fabrics can be readily cut and positioned on the mastermodel. Plies can also be easily and quickly repositioned where needed without damaging the underlying laminate stacks. When being placed on vertical surfaces the use of the Airtech Airtac2 spray adhesive provides enough tack to hold fabrics in position. Recent additions to the Airtech range include Econotac, a lower cost alternative, and TackStrip, an adhesive coated mesh.
After a dry fabric stack has been completed, the laminate is covered with peel ply and then a resin distribution mesh. The mesh provides a enhanced resin flow over the laminate enabling transport of resin to the whole tool surface. The peel ply provides means of removal of the mesh after cure, good resin flow through itself into the tool laminate and provides a textured surface for a subsequent support structure.
Resin distribution meshes are available offering different properties. Flow, drape and ease of placement being the main criteria for selection. The range offers mesh suitable for shaped and flatter geometries, high, medium and lower flow performance. Available data on flow characteristics of the mesh’s make the selection for application and strategy for resin supply line more simple to calculate.
Over the Resin Flow mesh, lines of resin feed are positioned. These are non-collapsable sections which stay open even under vacuum pressure and provide a fast supply of resin from the supply tubing onto the laminate surface.
The introduction of the Toolfusion product range is claimed to offer technical and cost advantages over the existing hand laminated tools and prepreg moulded tools.
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