Hand Layup starts with first coating the mold with a layer of filled resin called the surface coat. Dry fiber reinforcements then placed onto the wet surface. Addition of more fiber and resin happens successfully, till the resin is systematically worked into the fibers using a roller with curing under normal atmospheric conditions. Typically used for making wind turbine blades.
The function of Vacuum bag is to provide compaction pressure and consolidation of the plies within a laminate by creating a pressure differential between the inside and the outside of the bag using a vacuum pump, a hose, and a sealed film membrane. Vacuum bagging is also used to remove excess resin and gases from a laminate during processing. Typically used for making large racing car/ yacht components.
Prepeg Layups happen in an environmentally controlled clean room for precise temperature and humidity settings. Prepreg materials allow for the very precise resin to fiber ratios and accurate control of fiber orientation in the final laminate. Typically used for making structural components in aircraft and race cars.
In Vaccum Infusion, all the reinforcements are placed dry, vacuum bagged, and then the resin is introduced through tubing using vacuum pressure and then cured. This process works due to fluid dynamic principles because the low-pressure differential under the bag dictates the flow of the resin. Typically used for making yacht and vehicle body panels.
Resin Transfer Molding (RTM)
RTM is a process where the mixed resin injects into a closed mold containing fiber reinforcement. RTM is used to produce a part with a good surface finish on both sides and is well suited for complex shapes with large surface areas. Typically used for making aircraft and rail components.
In pultrusion, fiber reinforcements are pulled through a heated die to form a cured composite profile. The reinforcements are pulled off creels and guided into resin baths and then into a custom tooling called performer where the excess resin is pushed out. A heated die pulls the impregnated composite into it for curing and exit as the desired shape. Typically used for making beams and girders.
In thermoforming, heat and pressure are used to transform flat sheet thermoplastics into a desired three-dimensional shape. A preheated sheet is transferred to a temperature controlled, preheated mold, and conformed to its surface until it is cooled. Typically used for making panels.
Compression molding uses a heated matched mold similar to matched die and has used thermoset sheet molding compound or bulk molding compound as molding materials. A hydraulic cylinder is used to bring the mold halves together, providing simultaneous heat and pressure causing the thermoset matrix to liquefy and flow into the mold where it chemically reacts are cures. Typically used for making high volume composite parts.