Typically, this process uses a low viscosity (100 to 1000 cP) polyester or vinyl ester resin along with fiberglass fibers to create a composite.
The type of resin used will primarily determine the corrosion resistance, heat distortion temperature, and surface finish.
[4] Resins used in this process must have low viscosities due to the limited pressure differential provided by the vacuum pump.
For VARTM to create high quality composite parts it is crucial that air leakages are avoided.
An infrared detector, can then be used to determine if there are any heat releases on the surface of vacuum bag, which would be an indication of the presence of an air leak.
However, parts can be manufactured with an A-class finish on both sides with RTM due it having both a top and bottom mold.
This process offers the benefit of not requiring an expensive autoclave while also being capable of producing large, complex aerospace-grade parts.
For instance, LOCKHEED Martin Space Systems (LMSS) experienced a manufacturing cost saving of up to 75% when it began to produce the quarter section of the equipment bay for the Trident II D5 missile using VARTM.