Approximately 30% of all plastic
products in the world are produced by an injection molding process. Within this
another 30% are produced using a custom injection molding technology. There are
basically six steps involved in the normal injection molding process. The first
step is the clamping of the mould, the clamping unit makes for one of the three
units of the molding machine. The other two being the injection unit and the
mold, once the clamping unit holds on to the mold, the molten plastic is
injected into the mold by the injection unit. The plastic is fed in the form of
tiny pellets onto a hopper. These are then allowed into a cylinder where they
are heated into a molten state and injected into the mold. The steps that
follow are referred to as dwelling phase. It basically involves making sure all
the cavities in the mold are fully filled. The mold is then allowed to cool
with the clamping intact. Finally the mold is opened and the component is
ejected out. The biggest advantage of plastic injection molding is the cost
factor of the produced parts, especially when you need large number of
parts.  The disadvantage is the cost of
manufacturing the molds; a simple injection mold can cost you $3000 while the
bigger complex ones can run into several hundreds of thousands.

Rapid Prototyping: Rapid
Prototyping is the process of automated manufacturing of physical components
using solid freeform fabrication. They are used in a wide range of
applications, everything from medical to fine art. Rapid Prototyping machine
works by taking virtual models from software and then converting it into
extremely thin, horizontal cross-sections and then goes onto create each of the
cross-section in physical space in a cyclic manner until the model is completed.
Rapid Prototyping is a WYSIWYG process in which the virtual model bears
identical resemblance to the finished physical model. Additional fabrications
allows the machine to lay down layers of sheet, liquid or powder material and
build up a series of cross-sections These layers are finally automatically
fused together to render the final product. The main advantage of rapid
prototyping is the ability to create any shape no matter how complex the
geometry is. The commonly used data interface between the machine and the
software is the STL format. It works by approximating the geometry of a part
using triangular facets, smaller the facets higher will be the surface quality.
The word “rapid? is used relative top conventional methods which take days to construct
a model depending upon its complexity. 
Rapid prototyping can create the model within a few hours, though it is
highly dependent of the type of machines and the size of the model. There have
been several new technologies available for rapid prototyping including Fused
Deposition Modeling, Selective laser sintering, 3D printing , and Electron Beam
Melting.  

Prototyping Injection Molding is a specialized method of
combining traditional plastic injection molding. CAM software are able to
combine rapid tooling and plastic injection molding  in order to quickly create small quantities
of any thermoplastic part.

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Tags: cross sections, custom injection molding, injection mold, injection molding process, injection molding technology, injection molds, molding machine, molten plastic, molten state, physical components, physical space, plastic injection molding, rapid prototyping machine, six steps, solid freeform fabrication, thermoplastic injection molding, tiny pellets, using solid freeform fabrication, virtual model, virtual models

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