Plastic Material

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  • Topic: Injection molding, Plastic, Piping
  • Pages : 14 (3518 words )
  • Download(s) : 199
  • Published : May 24, 2013
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|Just about everyone knows that plastic valves, pipes, tanks, and fittings are molded, but there ís a bit more to it than that. Knowing something | |about the processes that are used to produce these products will help to make you more knowledgeable in selecting and using them in various | |applications. | |  | |1 | |Extrusion | |Pipe is one of the more common types of plastic product we are familiar with. Pipe is produced by an extrusion process. Basically extrusion can be | |defined as forcing a material through a die orifice. This die orifice produces the final shape of the finished product. It is probably a bit of over| |simplification, but extrusion is somewhat analogous to squeezing toothpaste through a tube.  | |An engineering explanation of plastic pipe extrusion would be something like this: plastic pellets or granules are thermally fluidized, homogenized | |and continuously formed. Or, in other words, plastic resin granules are heated and melted, then mixed and formed into pipe. Pipe is not the only | |product produced by the extrusion process. Plastic tube, sheet, wire and profile shapes are all also manufactured by this process. In fact, the | |plastic resin granules or pellets used for injection molding are produced by extrusion. A long strand or filament of extruded plastic is chopped or | |cut into pellet-sized pieces to produce plastic injection molding materials. | | | |Extrusion produces an inherently strong finished product. More so than a molding process. This is one of the reasons that plastic pipe is rated at | |higher pressures than injection molded plastic fittings. | | | |2 | |Injection Molding | | | | | |When people talk about molding, they're usually referring to injection molding. This is the manufacturing process that is used to produce the | |plastic parts that valves are manufactured from, as well as plastic pipe fittings. | |An injection molding machine uses heat to melt plastic pellets. The molten plastic is then forced, under very high hydraulic pressure, into a mold. | |Cold water circulating inside the mold cools the plastic and it solidifies into the shape of the mold cavity, producing the fitting or valve | |component part. ...
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