Plastics is the material of choice of most Product developers . Since
this a forum, I thought
I’d discuss a few plastic processes to make you think about how to get a
project done.
Simplified, making plastic parts involves heating plastic until molten,
forcing it into a cool,
closed mold, waiting until it is solid and then it is ejected from the mold.
There are two costs associated with plastic. One is the cost of building
the mold.
Molds are a reverse engineered copy of a part, usually cut out of metal
using machine tools.
The second cost is the cost of each part or run off the Mold.
Injection Molding is geared for high volume production. It can be an
expensive process.
It is associated with more solid forms of plastic where you force
plastic into a mold to fill
in all the spaces of the mold. Look around you. Most plastic parts are
injection molded.
The mouse you’re using. The CRT cover, computer case, Ink pens, cups are
all injection molded
Blow Molding is a process forcing thermoplastic material into a hollow
mold usually with
compressed air. This is the way they make items like plastic milk jugs.
It is quick and the molds
are less expensive since you have a hollow mold.
Vacuum Forming or thermoforming. They take a sheet of plastic heat it up
and then vacuum
it down over a mold. They can do up to 1/4” thick material. Examples of
this process include
the plastic bodies of R/C cars, or chocolate molds for candy. Product
packaging is done
this way, where they vacuum seal clear plastic around a product or
clamshell packaging.
This process is inexpensive. You can even make your own Vacuum Form Machine
Rotational Molding They use a hollow mold, pour in a measured amount of
plastic resin,
move it to a heated oven and rotate or slow spin the mold so that the
melted plastic coats
the inside of the hollow mold. Examples would be Little Tikes plastic
playground toys or
some hollow plastic furniture. The advantage over Blow Molding is that
you can get a
thicker wall where strength is needed.
Extrusions or Pultrusion is where they force plastic through a Die into
a particular shape.
They do this with plastic pipe or you could have a “C” shaped plastic or
hook shape.
You can make the length of the product as long as you want and then cut
it to the length
that you need.
I am not an expert in the field of Plastics, but I work with people who
are and can do
these processes. I hope that I can spark the inventor in you and get you
to think that there
are other processes that might be less expensive to manufacture a
plastic product.

Rich Freese
Arch City Service
(www.invention-mfg.com)