Vacuum injection

Also called vacuum injection, at low or high pressures, RTM (Resin Transfer Molding) is a technology that through its use has brought an extraordinary improvement in both the quality and cadence of production, compared to the process of manual rolling and simultaneous projection. Thus, a complete part can be made at an interval of up to 6-8 times smaller than the classic procedures, obtaining an increased productivity, motivated by the need to make medium or large series of parts.

Injection in the closed mold with the help of the vacuum

The fiberglass is placed in the mold, taking the shape of it and implicitly of the piece to be obtained. A second mold (father) is then attached to the first (mother mold), and the resin is injected into the cavity thus obtained. A vacuum pump can be applied to force the full impregnation of the fiberglass fabric. Once the fabric is impregnated, the resin injection holes are closed and the part is left to cure. Both injection and polymerization can be done at room temperature and at higher temperatures, for example in the oven. Polyester, epoxy, vinyl ester and phenolic resins can generally be used.

The main advantages are obtaining parts with high fiber content with implicitly improved mechanical properties and reduced air gaps, good environmental control for both health and safety of operators, reductions in production costs for large parts with simple shapes. The main drawback is the high cost of equipment, the increased risk of marking on parts with gelcoat finish, unimpeded areas that can lead to scrap parts, all depending on staff training.

Typical applications are complex parts for the aviation and automotive industry, train seats, etc.