Vacuum bag moulding

Variations on this basic process are (i) vacuum bag moulding and (ii) pressure bag moulding. In the former process a flexible bag (frequently rubber) is clamped over the lay-up in the mould and a vacuum is applied between the moulding and the bag. This sucks the bag on to the moulding to consolidate the layers of reinforcement and resin. It also squeezes out trapped air and excess resin. The latter process is similar in principle except that pressure is applied above the bag instead of a vacuum below it. The techniques are illustrated in Fig. 4.67(b) and (c). 

Figure 5.24 shows the principle of vacuum bag moulding after draping. 

This process (Figure 5.25) resembles vacuum bag moulding but the vacuum is replaced by pressure. After the composite has been manufactured onto its mould ... 

Vacuum bag moulding (autoclave process) Prepreg is encased in flexible bag a vacuum is applied to draw the prepreg against a mould surface. Heat is applied. Process carried out in autoclave Very large structures prototypes short production runs high fibre content... 

Manufacturing methods for composites vary from manual to fully automated processes, whereby the latter have better quality control than the former. Wet layup, pultrusion, and filament winding are all discussed in some detail, while other techniques such as pull-winding, resin transfer moulding, vacuum bag moulding, and injection moulding are left to specialized composite materials texts. 

Pressure Bag Moulding—A similar process to vacuum bag moulding, with pressure being applied to a rubber bag to aid consolidation of a laminate. 

Vacuum Bag Moulding—A process in which the lay-up is cured under pressure generated by drawing a vacuum in the space between the lay-up and a flexible sheet placed over it and sealed at the edges. 

Vacuum bag moulding for retrofitting is a semi-automatic resin infusion under flexible tooling (RIFT) technique, which allows production of quality composites. In the RIFT process, dry GF are pre-formed in a mould and are taken to the side and attached to the structure. A resin supply is then channelled to the prepreg, and both are enveloped in a vacuum bag. The flow of resin into dry GF (preform) develops the composite material and the adhesive bond between composite and structure as well. 

A 121-149 C cure epoxy with 104"C dry service capability which can be impregnated via hot-melt or solution techniques. Formulated for shrink tape processing but autoclave, press and vacuum bag moulding can also be used. Typical applications include tubular structures such as fishing rods, golf shafts and bike components. 

A 121 C cure self-extinguishing and solvent resistant epoxy designed for use in structural laminates and honeycomb core (to which it is self-adhesive) sandwich panels for aircraft exteriors. Designed for autoclave, but suitable for press and vacuum-bag moulding. 

A 121°C cure, self-extinguishing, self-adhesive, solvent resistant, epoxy resin with a good dry service temperature, suitable for autoclave, press or vacuum-bag moulding. Co-curable with 7714A, which provides considerable design flexibility with respect to the use of hybrid lay-ups. Designed for use in structural laminates and honeycomb core sandwich panels for aircraft. 

A 121 C or 149°C curing epoxy with a good 104 dry service capability. Although formulated for autoclave use, can be press and vacuum bag moulded. Can be impregnated via hot-melt and solution techniques, with typical applications including aircraft control surfaces and wing-to-body fairings. 

A 121 C cure epoxy designed for use in structural laminates. It is especially effective when used in the construction of large, thick laminates for marine and submarine applications. Whilst designed for autoclave use it can be press and vacuum-bag moulded. 

An unaccelerated, halogenated system for the manufacture, principally by hand-lay or spray/projection, of fire retardant mouldings meeting the M2 (French) classification. Can also be employed for cold-press moulding and vacuum bag moulding. 

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