Vacuum bag only

Key words out-of-autoclave (OoA), liquid composite molding. Quickstep, electron beam, microwave, vacuum bag only (VBO). 

Nutt, S. and Boyd, J., Out-of-autoclave processing with vacuum-bag-only (VBO) prepregs . http //www.ltt.de/uploads/pdfs/Events/ILA2006/ILA06 Praesentat ... 

Vacuum bags are effective not only in applying pressure, but also in withdrawing any volatiles produced in curing. This type of assembly is usually accompUshed with flat panels, or panels of simple contour, where light... 

RIFT or vacuum resin infusion is a hybrid of RTM and vacuum bag molding. In RIFT, one mold face of RTM is replaced by a flexible polymeric bag and resin is introduced into the mold by vacuum only. The process is better known in the USA as SCRIMP, which is a patented process. During resin infusion, the initial dry fiber compaction affects the permeability to resin flow and is time dependent, but when the resin enters the fibers, it appears to act as a lubricant and leads to further compaction. 

A recent introduction to prepreg technology is the use of a resin system such as 3M s Scotchply SP 381, which can be used in a one side tacky (OST) form. Processing using a vacuum bag enables an easy path for air to exit between the plies prior to resin saturation and achieve a composite with less than 0.4% voids using only a vacuum cure. 

In the process with a flexible mold half, also called vacuum bagging, compacting the fibers is only done using ambient air pressure. Because the main task of such molds is the contour shaping of the component, they can be less complex than closed molds with two fixed mold halves. 

From the above range of film adhesives, it is clear that this application can tolerate cures from 120°C to as high as 175°C and this is generally achieved using vacuum-bag lay ups and air-circulating oven cures autoclave processes are only used as and when absolutely necessary. 

Vacuum bags are effective not only in applying pressure, but also in withdrawing any volatiles produced in curing. This type of assembly is usually prepared using flat panels, or panels of simple contour, where light pressure suffice to hold mating surfaces in contact. Such an assembly can be laid out on a steam or electrically heated water-cooled table. A rubber blanked or plastic sheet, such as polyvinyl alcohol, is placed over the assembly and sealed to the table with a bead-type seal. The table is provided with a pipe or... 

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