Rapid Plastics - Injection Molding's Basics

Injection molding is a manufacturing technique forThe ejection phase is the last phase where the
making parts from both thermoplastic andremoval of the cooled, molded part from the
thermosetting plastic materials. Heated, fluid plasticmold cavity is done.
is injected at high pressure into a mold, which isPelletized or powdered materials that are used in
the opposite of the desired product shape.injection molding machines are mostly:o Ethyleneo
Injection molding is widely used for manufacturingPolystyreneo Polycarbonateo Polypropyleneo
a variety of parts, from the smallest componentAcrylonitrile-Butadiene-Styrene (ABS)o Nylon
to entire body panels of car.The process ofThe use of these basic steps in sequence or as a
injection molding can be described in four simplecycle is the process of injection molding done to
steps. These include Plasticizing, Injection, Chilling,obtain or manufacture parts. Cycle time usually
and Ejection. Each of these steps is differentranges from 10 to 100 seconds and are controlled
from the other and the right procedure is requiredby the cooling time of the melted plastic. The
for the successful completion of the total process.melted plastic comes from hard plastic pellets that
These steps can be discussed as follows:are fed into the hopper of the injection-molding
Plasticizingmachine. The pellets or plastic powder is melted
IT involves the conversion of the polymerinside the machine and then forced into the mold
material from its normal hard granular form atthrough a nozzle by a long screw within a heated
room temperatures, to the liquid which iscylinder. It is the most common method of
necessary for injection at its correct meltingproduction, with some commonly made items
temperature.including bottle caps and outdoor furniture.
InjectionInjection molding typically is capable of tolerances.
This is the stage during which this melt isPlastic molding applications are used in medical field
introduced into a mold to completely fill a cavitylike components for blood analyzer equipments,
or cavities.heart pump parts, orthopedic devices and custom
Chillingknee braces. In automotive engineering it is used
It is the act of removing heat from the melt tofor mechanical levers, gears, gaskets and
convert it from a liquid consistency back to itsswitches. It is also used for aerospace,
original rigid state.automotive, avionics and computer components.
Ejection