If you’re new to plastic injection molding, the process can
seem mystifying and a bit daunting. Today, we’re going to take a peek behind
the curtain and make sense of injection molding from start to finish. In the
process, we’ll help you see exactly how easy it can be to take your next
project from idea to finished product.
In the Beginning:
Proper Planning
Each successful product begins not with plastic injection
molding service, but with a plan. Unlike many other plastic injection molding companies, you will get assistance at every step in the injection molding
process when you select the best firms. You can come to the with a simple idea,
which will help you to refine and prototype.
The Injection Molding
Process
Companies have been doing plastic injection molding for more
than a century. Many of the materials and processes have evolved. These days,
sophisticated computer modeling increases accuracy and tolerances, and new
materials like biopolymers are revolutionizing the industry. For all those
changes, there’s also much in the process that’s remained remarkably
consistent.
It starts with mold making, the tooling of a two-piece metal
mold that will receive molten plastic. During the initial part of the molding
process, both halves of the mold are kept tightly shut.
Next, raw plastic resin in pellet form is fed into a hopper.
The pellets may be purchased pre-colored, or colored using pigments during the
injection process. The plastic pellets are melted down under high heat and
subjected to extreme hydraulic pressure in excess of 15 to 30 thousand PSI.
The resultant resin is shot into the closed mold through a
sprue. From the sprue, it flows to a runner, a channel that allows the liquid
plastic to flow to gates — subchannels leading to the cavities in the mold that
contain the imprint of the finished product. The material is allowed to cool
and return to a solid state, whereupon the mold opens and the part is ejected.
If you’ve ever purchased a plastic model kit, you have some
idea of what the next step looks like: a series of plastic parts attached to
remnants of the sprue, runner, and gate. Once the parts are separated, the
leftover plastic can be melted down for re-use to prevent waste and reduce
costs.
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