Three dimensional blow molding

Finally, it is worth mentioning the more recent three-dimensional blow molding in which a robot arm optimally positions the parison in the mold cavity, to minimize trim-off, and to produce complex shapes, such as automotive parts. 

Engineering thermoplastic blowmolding developments are gaining, such as the three-dimensional blow-molded automotive coolant ducting, and higher-MW, higher-melt-strength BPS for parison formation [16]. 

S. Wang, A. Makinouchi, and T. Nakagawa, Three-dimensional Viscoplastic FEM Simulation of a Stretch Blow Molding Process, Adv. Polym. Technol., 17, 189-202 (1998). 

Repeat this scenario with just about any common object you can think of, and you begin to understand why polymers are so common. Plastics come in an extremely wide range of compositions, with different physical and mechanical properties, chemical resistance, and cost. They can be molded, blow-molded, extruded, and shaped into an infinite variety of one-, two-, and three-dimensional shapes and objects. They can be made optically clear translucent, opaque, textured, and multicolored. They have made available to all of us household items that were once enjoyed only by the extremely wealthy (Wascher 1988). Thus the evolution of what many call the Plastic Age was inevitable. 

S-glass See fiberglass type, shape See die shape product shape, shape and volume change See dilatant. shape, blow mold complex See blow molding, extruder, three-dimensional. 

Blow molding is complicated by the complex stress field set up in the materials when the parison is inflated. This amounts to a biaxial stretching of the molten polymer and it is difficult to obtain material data under these conditions so that simulation may be performed. Despite this, much work on the inflation stage has been done, mostly with the aim of determining the final thickness distribution. Recently parison inflation has been simulated using three-dimensional finite elements and with remeshing of the parison as it inflates to minimize error from element distortion. ... 

Sequential blow molding is used for producing bent three-dimensional shapes, for example, a convoluted heat exchange tubular panel and filler pipes in automobiles. The parison is deformed and then manipulated with programmable 3-D manipulators or six-axis robots before being placed directly into a mold cavity. 

Blow Molding. The process of blow molding also applies only to thermoplastics. It is similar to thermoforming in that it uses a difference in pressure to force softened thermoplastic material to adopt the shape of a mold. Blow molding uses three-dimensional molds, however, and is typically used to produce open structures such as plastic bags, bottles, and other similar objects. In blow molding, a metered quantity of plastic material is set into a mold, where it is then blown outward by a sudden blast of heated air to the shape of the mold. The method is most suitable for open, three-dimensional shapes having little or no surface detail. 

The use of computers in blow mold design is generally accepted. In the area of product design and for CNC (Computerized Numerical Control) programming, three-dimensional (3D-CAD/CAM) systems are preferred. 

Wang, S., Makinouchi, A., and Nakagawa, T. (1998) Three-dimensional viscoplastic FEM simulation of a stretch blow molding process. Adv. Polym. Technol, 17,189-202. 

As with blow molding, the process is capable of producing very large three-dimensional shapes such as those found in recreational equipment and agricultural tanks. Because rotational molding operates with open molds at essentially ambient pressure, tooling is economical and can be fabricated from sheet metal. 

Advantages. Blow molding is an extremely versatile process that can be used to produce moderately complex hollow-shaped parts that are truly three dimensional in shape. Small, hollow parts can be produced with great precision quickly using the injection molding process, while large, complex parts can be manufactured by EBM. 

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