Pultrusion process operation

The composite can be made using the pultrusion process, but this is difficult to operate since the resins cure by a condensation reaction. Filament winding enables the fiber to be placed precisely onto a removeable mandrel and achieve a high fiber content. This technique more suited to handling untreated, unsized fiber and is used to make rocket motor nozzles. 

The basic pultrusion process can be divided into the following operations ... 

Gibson and coworkers [2] emphasized that the preheating section of their thermoplastic pultrusion process was of crucial importance to a successful operation. Besides the results achieved with CF/PEEK tapes, these authors presented a wide range of interlaminar shear strength (ILSS) data for pultrudates from glass fiber (GF)/polyamide 12 (PA12) tapes. 

In contrast to the pultrusion process, the production speed and the maximum size of the profile are not limited by the required pulling forces. Due to the use of release films, there is no adhesion between the polymer and the surface of the mold. Furthermore, the friction between the release film and the tool is minimized because of the semi-continuous operating principle of the CCM process. 

A numerical model has been developed by Viola etaL (1990) to optimize the operating parameters of a pultrusion line. Their model incorporates a onedimensional finite difference simulation of the pultrusion process. Based on given target parameters, the model primarily optimizes the temperature set points along the die. 

Michael, B. (Airbus operations GMBH) (2011), Pultrusion process for production of a continuous profile. Patent Application Publication, US2011/0049750A1, 3 March 2011. 

Moschiar S M, Reboredo M M and Vazques A (1998), Pultrusion Processing , In Cheremisinoff N P, Advanced Polymer Processing Operations, Westwood, NJ, Noyes Publications. 

If the filaments are not wound onto a mandrel but simply gathered into relatively large bundles and led slowly into a heated consolidation zone, emerging from a die partly or completely cured, the primitive essentials of pultrusion are present (Fig. 2.3(b)). This process began as the thermosetting resin equivalent of extrusion, that is, it was a continuous operation for manufacturing profiles, such as rod and channels. The method has been extended to fibre reinforced thermoplastics. 

Table 4 lists the operating conditions typically used in preliminary tests on the pultrusion line. In these tests, well defined U-shaped profiles with smooth surfaces (cross-section 24x4 mm, 2 mm thick) were produced. The towpregs used in the process were made from the GF/PP system (Table 1). 

Wu and Joseph (31) simulated the pultrusion heat transfer in die die and have determined the different conversion and temperature composite profiles for different pulling velocities. They point out the importance of automating the process by using an expert system in order to optimize the operations setpoints, manage emergency conditions and close the quality control loop with the information available, such as temperature measurement, product quahty, pulling velocity, pulling force requiied and the extent of reaction. 

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