Processing resin transfer

Table 9.71 Basic processing (resin transfer, spray, hand lay-up, mat/preform compression, and...

Table 9.72 Basic processing (resin transfer, injeetion, pultrusion, and reaetion injection) methods as a function of part design...

Methacrylate monomers are most effective with derivatives of bisphenol A epoxy dimethacrylates, in which the methacrylate—methacrylate cross-linking reaction proceeds at a much faster pace than with styrene monomer. This proves beneficial in some fabrication processes requiring faster cure, such as pultmsion and resin-transfer mol ding (RTM). 

Resin transfer molding With vacuum assisted RTM, this process can be called infusion molding. RTM usually uses liquid TS plastics that is transferred or injected into an enclosed mold usually at low pressures of about 60 psi (410 kPa) in which reinforcement... 

SCRIMP process This Seeman Composites Resin Infusion Process (SCRIMP) is described as a gas-assist resin transfer molding process. As an example glass fiber fabrics/ thermoset vinyl ester polyester plastic and polyurethane foam panels (for insulation) are placed in a segmented tool. A vacuum is pulled with a bag so that a huge amount of plastic can be drawn into the mold (Marco process approach). Its curved roof is made separately and bonded to the box with mechanical and adhesive fastening. It is similar to various reinforced plastics molding processes. 

Table 8-32 Comparison of resin transfer, compression, and injection molding RP processes...

Resin transfer molding (RTM) is a hybrid of two polymer processing techniques we have already described transfer molding and reaction injection molding (RIM). The key difference is that a reinforcement is incorporated during molding to create a composite. 

Figure 7.90 Schematic diagram of a typical resin transfer molding (RTM) process. Reprinted, by permission, M. Schwartz, Composite Materials Handbook, 2nd ed., p. 4.56. Copyright 1992 by McGraw-HiU.

In this section a specialized set of equations governing transport of mass, momentum, and energy in resin transfer molding, injected pultrusion, and autoclave processing are obtained from the general balance equations presented in Section 5.3. This involves eliminating unimportant terms in the general balance equations based on the specific nature of the process. 

The stability, growth, and transport of voids during composite processing is reviewed. As a framework for this model, the autoclave process was selected, but the concepts and equations may be applied equally effectively in a variety of processes, including resin transfer molding, compression molding, and filament winding. In addition, the problem of resin transport and its intimate connection with void suppression are analyzed. 

Rigid caul plates are typically constructed of thick metal or composite materials. Thick caul plates are used on very complex part applications or cocured parts where dimensional control is critical. Many rigid caul plates result in a matched die configuration similar to compression or resin transfer molding. Parts processed in this manner are extremely challenging because resin pressure is much more dependant on tool accuracy and the difference in thermal expansion between the tool and the part. Tool accuracy is critical to ensure no pinch points are encountered that would inhibit a tool from forming to the net shape of the part. 

Liquid Composite Molding (LCM) is the common name for several similar processes for the manufacturing of polymeric fiber reinforced composites. Widely used processes that belong to this class are Resin Transfer Molding (RTM), Vacuum-Assisted Resin Injection (VARI), and Structural-Reaction Injection Molding (S-RIM). 

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