Pultrusion processing

This is a marriage of two processes pultrusion and compression moulding. A pultrusion in-feed system is employed for management of the reinforcement and to apply the resin mix but the conventional pultrusion die is replaced with one which will open and close. This allows variations in the cross section and linearity of the component which are not possible with pultrusion. 

Pultrusion is a manufacturing process that converts fibre reinforcements and resin matrices into finished composite parts. Unlike other processes, pultrusion enables continuous production in a highly automated and low-labour process that uses a heated die to give shape to the composite part. These features mean that, of the different manufacturing processes developed in the last five decades, pultrusion offers the best productivity/cost ratio (Zureick and Scott, 2000). 

The Automatic processes are those such as pultrusion, filament winding, centrifugal casting and injection moulding. 

Pultrusion is also used to make structural shapes from composite materials. The incoming material is generally unidirectional and must be pulled through the pultrusion die because the uncured composite material is entirely too flexible to push (as in extrusion processes). The incoming material can be preshaped by various guides and rollers as in Figure 1-18. 

Process used provides different control capabilities. As an example closed molding (injection, compression, etc.) provides fine detail on all surfaces. Open molding (blow molding, thermoforming, spray-up, etc.) provides detail only on the one side in contact with the mold, leaving the second side free-formed. Continuous production (extrusion and pultrusion) yields products of continuous length. Hollow (rotational or blow) produces hollow products. These processes can be used creatively to make different types of products. For example, two molded or thermo-formed components can be bonded together to form a hollow product, or they can be blow molded. 

Composite processing uses specialized methods. For thermoplastics, glass mat thermoplastic (GMT) is the main method but prepreg, lay-up, tape winding, pultrusion are also used to produce composites. SMC/BMC are the main processes for thermosets but lay-up is currently used for large parts and prepregs are used for high-tech parts. 

Process (Top Glass SpA) combining extrusion, pultrusion and moulding to produce threaded rod from Fulcrum. 

Figure 7.87 Schematic diagram of a typical pultrusion process. Reprinted, by permission, from M. Schwartz, Composite Materials Handbook, 2nd ed., p. 4.46. Copyright 1992 McGraw-Hill.

The ring opening polymerization of cyclic monomers that yield thermoplastic polymers of interest in composite processing is reviewed. In addition, the chemistry, kinetics, and rheology of the ring opening polymerization of caprolactam to nylon 6 are presented. Finally, the rheo-kinetics modelsfor polycaprolactam are applied to the composite process of reaction injection pultrusion. 

Among the more common thermoplastics from ring opening polymerization of interest in composite processing are polylactams, polyethers, polyacetals, and polycycloolefins. It has also been shown that polycarbonates can be produced from cyclic carbonates [22], Anionic ring opening polymerization of caprolactam to nylon 6 is uniquely suited to form a thermoplastic matrix for fiber-reinforced composites, specifically by the reaction injection pultrusion process [23-25]. The fast reaction kinetics with no by-products and the crystalline... 

In this section, we will describe the application of the rheokinetic model to adiabatic and isothermal pultrusion by the RIP process. Adiabatic pultrusion is defined as a pultrusion... 

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