Molding Methods (Processing Methods) for Carbon Fiber & Carbon Fiber Reinforced Plastics

This is a continuous molding method in which carbon fiber impregnated with liquid resin is drawn into a mold, and passed through it for heat-curing. It is suitable for molded products with a fixed cross-sectional shape, such as rods and pipes.

This is a molding method in which carbon fiber tow impregnated with liquid resin is wound around a mandrel, and then heat-cured. There are two versions of this method: (i) winding the carbon fiber while it is soaking in a resin bath; and (ii) winding the tow prepreg, which has been impregnated with resin. It is suitable for tube- and tank-shaped molded products.

In this method, a carbon fiber preform (carbon fiber preformed into a product shape, fabric, etc.) is placed in a pair of male and female sealed molds, and liquid resin is press-filled, impregnated, and heat-cured. The method of curing by vacuum pressure using only a female mold is called vacuum-assisted RTM (VaRTM). RTM is suitable for small and medium-sized products, whereas VaRTM is suitable for medium-sized and large products.

In this method, sheets impregnated with resin, such as prepreg or SMC, are stacked in a mold, and heat-cured while pressure is applied. Mitsubishi Chemical has established the prepreg compression molding (PCM) method using high-cycle and preform technology, and hybrid molding with SMC materials is also feasible. This molding method is suitable for mass-produced products.

Simply put, an autoclave is a pressure cooker. Prepreg is laminated onto a molding die, covered with bagging film (film used to create a vacuum), depressurized, and then heat-cured under pressure in an autoclave. This molding method is suitable for manufacturing high-quality and high-performance products, but the cost is high due to the long molding cycle.

As in autoclave molding, prepreg is laminated on a molding die, covered with bagging film, and depressurized, but the heat-curing is in a vacuum. Although slightly inferior to autoclave molding in terms of performance and quality, this molding method is inexpensive to operate, and can be used for relatively large molded products.

This is a molding method in which prepreg is wrapped around a mandrel (an iron core), taped, and heat-cured, after which the mandrel is removed. It is suitable for production of small and medium-sized products shaped as pipes and rolls. Mitsubishi Chemical's golf shafts and rolls are mainly produced by sheet-wrap molding.

This is a molding method in which the raw material, a pellet of thermoplastic resin (e.g. nylon, polycarbonate) reinforced with carbon fiber, is heated until it melts, and then injected into the cavity (void) of a mold. Although the mechanical properties are not as good, this molding method is suitable for molding complex shapes with short cycle times.