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- Information about technological processes
and working systems . Everybody can contribute with documentation,
that must be sended to info@rioweb.it
accompanied with the name of the source, and if possible the link
of the site one where there is the possibility of a deepening.
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Injection Molding
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- The method of forming objects from granular
or powdered plastics, most often of the thermoplastic type, in
which the materials is fed from a hopper to a heated chamber in
which it is softened, after which a ram or screw forces the material
into a mold. Pressure is maintained until the mass has hardened
sufficiently for removal from the mold.
- Injection molding is the most widely
used polymeric fabrication process. It evolved from metal die
casting, however, unlike molten metals, polymer melts have a high
viscosity and can not simply be poured into a mold. Instead a
large force must be used to inject the polymer into the hollow
mold cavity. More melt must also be packed into the mold during
solidification to avoid shrinkage in the mold. Identical parts
are produced through a cyclic process involving the melting of
a pellet or powder resin followed by the injection of the polymer
melt into the hollow mold cavity under high pressure.
- Injection molding can be used to form
a wide variety of products. Complexity is virtually unlimited,
sizes may range from very small to very large, and excellent control
of tolerances is also possible. Most polymers may be injection
molded, including thermoplastics, fiber reinforces thermoplastics,
thermosetting plastics, and elastomers. Structural injection molding
is also possible in which a core and skin may be made of different
polymers. Reaction injection molding and liquid injection molding,
which differ in the manner of mixing ingredients, involve the
injection of liquid polyurethane systems that polymerize within
the mold.
- A method of manufacture (typically involving
wood heads and face inserts) in which the material (ABS, epoxy,
graphite, etc.) comprising the head is heated to a liquid state
and injected under pressure into a mold. When the material hardens,
it takes the shape of the mold into which it was injected
- A hot, molten polymer is injected into a
cold mold. A screw apparatus can be used to inject the polymer
into the mold. After the part cools and solidifies, the mold is
opened and the part is ejected. No chemical reaction occurs during
the molding process. This molding process is termed injection
molding.
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