Advantages of Resin Film Infusion (RFI)
This is the process for which Film Casting Machine is most suited. The film cast on our machine will have dimensional accuracy, ensures desired resin volume factor, and helps the processor to manufacture composite sections of highest quality.
Autoclave curing using prepregs has been the gold standard for aerospace composites manufacturing. This technology has been by and large limited to aerospace applications primarily due to high cost. Resin Film Infusion (RFI) is a cost-effective alternative for autoclave-based processes for manufacturing of structural composites.
In the RFI process, polymer resin, for example epoxy, is cast in film form and sandwiched between two reinforcement layers. These layers are cut to share laid on the tool, and vacuum bagged. The rest is a standard vacuum bagging process at ambient pressure and elevated temperature thus doing away with the necessity of an autoclave. When heated, resin becomes fluid, it flows and wets out the fibers of the reinforcements. Latent curing agents premixed in the resin, act at an elevated temperature and cured parts are made.
The RFI composite processing replaces the conventional aerospace manufacturing technique of autoclave curing at much lower cost.
Large and thick structures can be manufactured without necessity of an autoclave. RFI offers possibility to manufacture structures with practically no thickness limitation. Composite structures as thick as 78mm have been realized through this process. The structure is with fiber volume content as high as 57 percent and near zero void fractions.
Products manufactured through RFI processes have excellent structural properties with near-zero void content. The resin film needs to be stored at controlled temperature depending on the resin system, similar to prepregs used in autoclave processing. However, since sandwiching can be done on demand, only the resin film needs to be stored at lower temperatures. Thus, doing away with the issue of shelf-life which is typical to prepregs. Resin film can be cast for Just-In-Time use and avoid shelf-life issues completely.
Prepregs are not drapable as dry fabrics and more prone to creasing in complex areas of molding. RFI offers added advantage of excellent drapability
As for epoxy system, resin-hardener mixing and its film casting are carried out under strict control, reproducibility and quality of fabricated parts are not reliant on operators.
To achieve better properties, resins can be modified using nano fillers resulting in hybrid composites. Structural composites modified with nanofillers can be realized only through resin film infusion. Since the process involves a local flow of molten resin, uniform distribution of the filler particles is ensured which otherwise is impractical in conventional liquid composite molding techniques.
Repeated re-bulking for thick composite lay-up is not required
This process has special significance for large structures as there is no possibility of an incomplete infusion
Currently only one comparable commercial product is available elsewhere in the world. However, system developed by us is superior in many aspects and extremely cheaper when comparing with US or European sources. Also, our system can be further improved considerably with Nano fillers.
Vacuum Assisted Resin Transfer Moulding (VARTM): Again, process ideally suited for manufacture of large structural composites at much lower cost. Properties are inferior as compared to RFI; however, process is cheaper. Wind turbine rotors and boats are currently manufactured with this process. We are confident to place on record that you can perfect this technique for far more critical applications for which, solutions may not be available elsewhere. With the data feeding & recording facility provided in the machine, customers can establish process monitoring capability so that there is no loss of product during infusion and curing.