All About Injection Molding

Injection molding is a very common and
widespread means of production used especially in the plastic industry. A whole
range of plastic products are made through this means, from buckets to bottle
tops to flowerpots, plastic helmets, tool handles, toys, to machine parts.
Indeed injection molding produces much of the plastic products we use daily.
Products made from injection molding vary in size, shape, and functionality and
that might give us an idea as to why it is always readily employed.

The reason for its prevalent use is due to its
cost-effectiveness; especially when the product has to be produced in vast
quantity, speed of production, and repeatability, in that the process can be
repeated over and over again.

Does Injection Molding Work?

From the name, one can infer that it has to do with ‘injecting’ a substance for ‘molding’. In simple terms, what Injection Molding involves is injecting plastic into a mold, and as the plastic sets, it retains the exact shape of the mold.

Technically, plastic, either in granular form
or pellets, is fed into the machine through a hooper. From the Hooper, the raw
plastic now travels through a section where they would be led by a screw to the
point of injection. What this screw does is to apply pressure on the raw
plastic, slowly turning it and leading it to the point it gets injected into
the mold. While in this section, friction and heat, from heaters around the
base of the machine, heat it and turn the plastic into liquid or molten form.
It is this form of plastic that when injected into the mold, takes the shape of
the space around it, and retains it, slowly cooling, until it is ejected.

Both thermoset and thermoplastic plastics can
be used for injection molding, but most companies prefer thermoplastic because
it can be used again and again, and some of the pellets used can be from
recycled thermoplastic plastic, unlike thermoset which can only be used once.

Is Injection Molding A More Preferred Means Of Production?

There are various reasons as to why companies
readily employ injection molding in production, and some of these reasons

  1. Cost-Effectiveness

Injection molding is the most preferable
option when a company needs to cut back on cost, especially when the items are
to be produced in bulk. Once the machine is available, production can start,
and in time, production would begin to pay for itself.

This helps manufacturers save some money,
especially for labor.

  • Scale
    Production and Repeatability

Similar to the previous point, this mode of
production is used in a situation where a particular product has to be produced
in great numbers, from a thousand, up to hundreds of thousands. The beauty of
injection molding is that you can produce the exact type of a product over and
over again, with great precision and accuracy, so that all are identical, as
long as you have the type of mold used from the start. The method can be
repeated over and over again.

  • Flexibility

This process is very favored because it can be
used to produce any form of an object, in whatever shape or size. Injection
molding is not limited unlike other forms of production. The only thing
important is to get the appropriate mold.

  • It Allows
    For Correct Detailing

For example, when producing the handle of a
tool, or other products that may need screws or a complex interior, injection
molding is the best option because it allows for proper detailing since the
plastic takes the exact form of the mold.

to Consider Before Going Into Injection Molding

  • Perhaps the key factor to consider is cost.
    Getting started, that is acquiring and setting up the machine can be quite
    pricey, but as time goes on, it would pay for itself, and sooner than you
    think, if you start work right away. Another way it could prove costly is with
    the molds. Ordinarily, you cannot use the same mold for every product as the
    mold for a bottle is different from that of a bucket. Molds see made from
    various materials, but the most common are aluminum and steel. Aluminum is used
    for being cheap, but it cannot be used for multiple productions, unlike steel
    that can be used up to a million times, although getting a steel mold can be
    more expensive. But like the machine, it would pay for itself.
  • Also, you have to keep in mind that every
    product you make has to be made by this process. This is something you do not
    want to forget especially when designing the product as you have to remember
    that it would be made by injection molding.
  • You also have to take into note the number of
    products you would be making. Anything from a thousand above would
    appropriately require the process of injection molding. Doing about a hundred
    or so may not be a very good idea, economically speaking.


Injection molding presents a lot of
advantages, and perks, making it a widely used option in a range of production,
especially when taking into account factors like cost, and scale of production,
making it almost the industry standard, and for its extensive use.

Adam Hansen

Adam is a part time journalist, entrepreneur, investor and father.