Manufacturing resin-transfer molding

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). 

The chapter is divided into a section on development of process cycles or plans and a section on in-process control. The tools to be discussed include design of experiments, expert systems, models, neural networks, and a variety of combinations of these techniques. The processes to be discussed include injection molding, resin transfer molding, autoclave curing, and prepreg manufacturing. The relative cost and difficulty of developing tools for these applications will be discussed where data is available. 

Liquid composite molding (LCM) processes such as resin transfer molding (RTM) have been long established in the automotive and aerospace industries as versatile technologies for manufacturing medium to large composite parts with complex geometries at low cost. All LCM processes involve the injection of a liquid resin into a dry fiber perform, and are... 

Resin transfer molding In the resin transfer molding (RTM) process, a low viscosity resin is transferred into a closed mold containing all the appropriate reinforcements and inserts as a preform. The air is normally evacuated from the mold, allowing the use of low resin injection pressures and epoxy molds. Manhole covers, compressor casings, car doors, and propeller blades have all been manufactured by RTM. 

SRIM is similar to RIM in its intensive resin mixing procedures and its reliance on fast resin reaction rates. It is also similar to resin transfer molding (RTM) (discussed later in this chapter) in employing performs that are preplaced in the cavity of a compression mold to obtain optimum composite mechanical properties. The term structural is added to the term RIM to indicate the more highly reinforced nature of the composite components manufactured by SRIM. 

Sozer E, Simacek P, Advani S. Resin transfer molding (RTM) in polymer matrix composites. In Advani S, Hsiao K-T, editors. Manufacturing techniques for polymer matrix composites (PMCs). Cambridge (UK) Woodhead Publishing Limited 2012. 

Resin transfer molding Low mold costs, low pressure molding, two good surfaces providing quick manufacture of wood molds and producing rather complicated small and particularly large parts to rather tight tolerances... 

The cyanate ester monomers are available from low-viscosity liquids to meltable solids. Ciba-Geigy produces a series of cyanate esters imder the trademark AroCy L-10. Cyanate esters are used in manufacturing structural composites by filament winding, resin transfer molding, and pultrusion. 

Manufacturers are introducing new proprietary products designed for specific end uses, such as resin transfer molding, that are silicone and stearate free. 

Sundsrud GJ, Advantages of a one-part resin system for processing aerospace parts by resin transfer molding (RTM), SME Composites in Manufacturing Conference, Pasadena, Jan 19, 1993. 

Figure 23.26 Dowty Rotol propeller blade root construction. Source Reprinted from Abraham D, McCarthy R, Design of polymer composite structural components for manufacture by resin transfer molding (RTM). SAMPE Europe Conference Exhibition, 407-415, 1999.

The resin transfer molding and liquid transfer molding processes are used principally for manufacturing fiber-reinforced composite parts in moderate to high volumes. The process combines the techniques of hand lay-up, liquid resin casting, and transfer molding, as discussed earlier in this chapter. 

Cyanate esters are used in the manufacturing of structural composites such as filament winding, resin transfer molding, and pultrusion. The cyanate ester resins have shown superior dielectric properties and much lower moisture absorption than any other structural resin used for composites. The glass transition temperature of cyanate esters is relatively high (250°C), but it requires cure temperatures greater than 177°C. 

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