Plastic has, quite literally, become the cornerstone
of our society. We make so many things from plastic that it is hard to
imagine what our lives would be like if it was never invented. With so
many of our everyday products being made of plastic, it is easy to
understand why plastic injection molding is such a huge industry.
Approximately
30% of all plastic products are produced using an injection molding
process. Of this 30%, a large amount of these products are produced by
using custom injection molding technology. Six steps are involved in
the injection molding process, after the prototype has been made and
approved.
The first step to the injection molding process is the
clamping of the mold. This clamping unit is one of three standard parts
of the injection machine. They are the mold, the clamping unit and the
injection unit. The clamp is what actually holds the mold while the
melted plastic is being injected, the mold is held under pressure while
the injected plastic is cooling.
Next is the actual injection of
the melted plastic. The plastic usually begins this process as pellets
that are put into a large hopper. The pellets are then fed to a
cylinder; here they are heated until they become molten plastic that is
easily forced into the mold. The plastic stays in the mold, where it is
being clamped under pressure until it cools.
The next couple of
steps consist of the dwelling phase, which is basically making sure
that all of the cavities of the mold are filled with the melted
plastic. After the dwelling phase, the cooling process begins and
continues until the plastic becomes solid inside the form. Finally, the
mold is opened and the newly formed plastic part is ejected from its
mold. The part is cleaned of any extra plastic from the mold.
As
with any process, there are advantages and disadvantages associated
with plastic injection molding. The advantages outweigh the
disadvantages for most companies; they include being able to keep up
high levels of production, being able to replicate a high tolerance
level in the products being produced, and lower costs for labor as the
bulk of the work is done by machine. Plastic injection molding also has
the added benefit of lower scrap costs because the mold is so precisely
made.
However, the disadvantages can be a deal breaker for
smaller companies that would like to utilize plastic injection molding
as a way to produce parts. These disadvantages are, that they equipment
needed is expensive, therefore, increasing operating costs.
Thankfully,
for these smaller companies, there are businesses that specialize in
custom plastic injection molding. They will make a mock up mold to the
exact specifications, run it through the complete process and present
the completed piece along with an estimate to complete the job to the
customer.
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