LCM processes involve the saturation of a fibrous bed with a liquid resin, which is then allowed to gel to form a composite part. The saturation process is referred to as an infusion. In general, the shape of the part is formed using a mould or moulds, and fluid motion is achieved by pressurizing the resin, pulling vacuum in the preform, or a combination of both. Many different variants of the LCM process have been developed, including Resin Transfer Moulding (RTM), Light RTM, Vacuum Assisted Resin Transfer Moulding (VARTM), and Structural Reaction Injection Moulding (SRIM), each with its own unique set of advantages and disadvantages.
Liquid Composite Molding (LCM) is one of the most cost effective and commonly used composite materials manufacturing techniques. In LCM processes, the basic principle is to inject resin into stationary fabric preform and saturate all gaps between the fibers with resin before the curing (gelation) starts. Resin Transfer Molding (RTM) is a typical LCM process, in which a fabric preform is placed inside a mold cavity and then the mold is sealed and closed. Resin is injected into the mold cavity to saturate the fabric preform. After the resin cures, the mold is opened and the composite part is taken out.
The following sections describe RTM and VARTM, two common LCM processes, as well as Mouldless VARTM and Closed Cavity Bag Moulding (CCBM), two variants of VARTM that have been developed at Carleton University.
3.1.1 Resin Transfer Moulding (RTM)