Continuous extrusion pultrusion

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. 

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. 

In contrast to extrusion, in pultrusion a combination of liquid resin and continuous fibers is pulled continuously through a heated die of the shape required for continuous profiles. Shapes Include structural I-beams, L-channels, tubes, angles, rods, sheets, and so on, and the resins most commonly used are polyesters with fillers. Other resins such as epoxies and urethanes are used where their properties are needed. Longitudinal fibers are generally continuous rovings. Glass fiber material (mat or woven) is added for cross-ply properties. 

Pultrusion is a process somewhat similar to extrusion in concept, in that it produces continuous profiles by forcing the plasticized material... 

The impregnated tows can be used for many applications which are generally subdivided into those where the fiber reinforcement is continuous (e.g. filament winding or pultrusion) and those where the tow is cut and the unidirectionally reinforced peUets (discontinuous long fiber reinforced thermoplastics) are then further processed into parts (e.g. in extrusion or injection molding). 

Extrusion. The process of extrusion is closely related to pultrusion. In extrusion, the plastic material is pushed through a die under pressure rather than drawn through with continuous fiber-reinforcement materials. Random-oriented fiber-reinforcement materials can be used in the extrusion process if they are blended with the molten plastic before entering the die. Extrusion can be used only to produce structures that have a constant cross-sectional profile along their entire length, as determined by the die profile. Quite complex cross-sectional designs can be produced in this way, but they are essentially only two-dimensional. 

Similar to the described combination of pultrusion and extrusion is the so-called pull-extrusion process, which is illustrated in Fig. 8.15. It enables the production of products which are reinforced with both continuous and discontinuous fibers in one profile. A thermoplastic polymer is molten in an extrusion unit. In a first step, the extrudate is combined with a continuous fiber strand. In the second step the remaining polymer is added with... 

The term pultrusion comes from the words pull and extrusion . It is the process where continuous fibres soaked in a polymer are pulled through a heated die and extruded (Hota et al, 2009). 

In contrast to extrusion, in pultrusion a combination of liquid resin and continuous fibers is pulled continuously through a heated die of the shape required for continuous profiles. Shapes include structural i-beams, L-channels, tubes, angles, rods, sheets, and so on. 

Continuous pultrusion (extrusion). Impregnated glass reinforcements are pulled by tension through resin tank, machined dies, and onto racks, drums, or creels. 

Pultrusion of profiles and pipes with continuous fibers, analogous to thermoplastic extrusion,... 

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