Injection molding is often ranked as the one of the commonly used processes in the production of plastic items. The popularity of plastic injection molding is often due to the fact that it is a fast process which can be used to produce vast quantities of identical plastic items ranging from disposable consumer goods to high precision engineering components.
Typically Produced Products
The majority of thermoplastics, such as nylon, polystyrene and polycarbonate are produced through the injection molding process, as are the majority of all plastic products ranging from micro parts to large components such as wheelie bins. Also, the fact that this process can produce items that range greatly in shape and size has resulted in the extension of the boundaries of plastic design and enabled significant replacement of traditionally used materials in part due to light weighting and freedom of design.
The Basic Process
The basic process involves the introduction of a material, via a hopper, into the injection molding machine. This molding machine consists of a heated barrel, equipped with a reciprocating screw (which is driven by a hydraulic or electric motor), which itself feeds the molten polymer into a temperature controlled split mold through a channel system of runners and gates.
The reciprocating screw plasticises (melts) the polymer as well as acting as a ram during the injection phase. The shearing action of the screw on the polymer also provides additional heating during this part of the process and the polymer is then injected into a mold which is created according to the required dimensions of the finished product.
The pressure used when injecting the polymer into the mold is very high and (depending on the material being processed) this pressure could even reach one thousand atmospheres.
The tools used in the plastic injection molding process are typically made out of steel (as it can be hardened and plated if required) and alloys of aluminium to allow increased cutting and hand polishing speeds. The costs associated with the production of the tools required in this process mean that injection molding tends to lend itself to high volume production of plastic products and components.
There is a large number of companies which specialise in the production of plastic components and products via injection molding and the supply of molds for the process. The fact that the service provided by these companies is demanded by a wide range of customers (including those in the defence and aerospace industries) shows the importance of this process and the necessity of its products.From Website
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