Prepreg, a combination of reinforcing fibers and matrix resin, is the starting material for many composite parts used in the aircraft, shipbuilding and plastic industries. There are many reinforcing fibers: E-glass, S-glass, aramid, quartz, carbon, Spectra, teflon, and many specialty, and non-woven reinforcements.
Resin systems include: epoxy, polyester, phenolic, silicone, polybutadiene, and cyanate ester. The test method for the verification of the physical characteristics of a prepreg systems include resin content, gelation time, volatile content, and resin flow. The use of braiding as a fabrication process is becoming more prevalent in the composites industry for design flexibility, ease of fabrication and economic consideration. Resin must be injected at a standard pressure or vacuum pressure on the braided perform. Standard pressure is the air pressure that will support a column of mercury 0.760 m high. Resins must have a low viscosity and must generate no volatiles upon curing. The several resins used are vinyl ester, polyesters, hot-melt bismaleimide and liquid epoxies. The viscosity range has been considered 200-600 cP and most injections are completed in 60 min. After the injection, the resin should be able to be cured 70-80 percent in 10 minutes in the heated mold.
Today, the resin vacuum pressure infusion process which uses a vacuum bag where part of the details are packed by hand. Dry textile preforms are resin impregnated, consolidated and cured in a single step eliminating costly prepreg tape manufacture and ply-by-ply layup. Under a high vacuum pressure, the laminate layers were saturated with vinyl ester or polyester resin. The quality control of the prepreg system and the impregnation of dry aviation parts includes the same control characteristics plus the homogeneity and impregnation control. The homogeneity impregnation is only possible if we use an automation process. This article describes the control needed for an automation process for the impregnation of prepregs and dry braided parts. The goal of the work was to evaluate a moving head resin at a hemispherical injection process for the impregnation a "complex" shape in the braided preform versus a resin injection process.