A Look At The Evolution Of Plastic Injection Molding Methods

You may be surprised to learn that many of the items we use on a daily basis have all been made using the same techniques. The different plastic injection molding methods allow us to create many objects ranging from simple items such as toothbrushes and hair clips to complicated items used in fields such as medicine. It is interesting to learn about plastic injection molding methods and the ways that they have changed over the years to create many of the items we use today.
Regardless of changes to the techniques themselves, the same basic principle applies to all plastic injection molding methods. Plastic particles are melted down and fed (or injected) by force through molds. These molds are chilled and this causes the plastic to harden. This chilling is accomplished by passing coolant around the mold so that the plastic can harden. After it hardens, it is ejected from the mold and is trimmed and finished so that it is ready for use. Although an early form of plastic was invented in the 1850’s, it was not until the 1870’s that the plastic injection molding process was developed. Early forms of plastic were very difficult to work with and a more malleable form of the material needed to be invented. Shortly after this more malleable form was developed, plastic injection molding methods were also developed.
One of the main changes has been in the materials which are used. Now, there is a greater variety of plastics that can be used in the injection molding process. Many of these plastics have different qualities that make them more desirable for certain applications. As well, it is also possible to add other materials to the plastic. This allows manufacturers to add coloring to the plastic and has given the industry much more versatility.
Molds are now available that are more complicated than they were in the past. Before, molds were usually created in two parts. One contained the molding cavity and the other piece was used to eject the finished product from the mold. Now, computer assisted manufacturing has allowed manufacturers to create more complicated molds that may have multiple sections. They are also able to add more detail to the sections of the molds.

The plastic injection molding process changed during the 1940’s. Due to the war, there was a higher demand for many of the products that could be manufactured using this process. A screw-type plunger was invented which made the process easier to complete. This was perhaps the first major change that this manufacturing process underwent. This was also when the mixing of plastics and colorants was developed. It is amazing to think about how many of the products in our lives are made with these manufacturing methods. Whether we are at home, at the store or even being treated medically, plastic products surround us each day. It is only when we think of how many are created using this process that we begin to realize how important it actually is.


Are you someone who is interested in learning how objects are made? If so, you may be interested in learning about plastic injection molding methods and how they have changed through the years. Ever since the mid to late 1800’s, this method of creating objects has been used in order to manufacture products such as toothbrushes and hair clips. Even items used in medical treatment can be created using these techniques. You may be surprised to learn that although there have been changes to plastic injection molding methods the same basic techniques are the same. Heat is applied to small granules of plastic. Once it has melted it is injected into a mold. The plastic hardens and, when it does, it is ejected from the mold. This hardening is normally achieved using coolant which passes around the molding chamber. Otherwise, it would be difficult to cool the plastic evenly and this could lead to flaws in the finished product. Any tags or excess plastic is removed and the product can then be used.
Many people think that plastic is a very modern invention and they are surprised to find it has actually been around in one form or another since the mid to late 1800’s. Early plastic was very hard to work with and difficult to shape into different items. Inventors worked with the basic material and were able to develop a form that was more durable and easier to work with. Shortly after, plastic injection molding methods were also developed. Although the basic techniques have remained similar in many ways, the materials that are being used have changed. Plastics are now available in a wider variety than they were when plastic injection molding methods were first developed. Now, plastics with different melting points are available and it is also possible to add different coloring materials and additives that give specific qualities to the finished product are e also available.


They had only two parts. The first was the section in which the actual shaping took place. The second was a section that allowed the finished piece to be ejected easily. Now, very complicated molds exist that may have multiple sections or parts.
It is interesting to note that it was not until the 1940’s that plastic injection molding methods truly became popular. Because of the war, many different items were needed that could be created using these methods. In order to make the process easier to control and to make it possible to add different chemicals, the screw type injection process was developed. When we think about how many products used in daily life are made using this process, the list may seem endless. It does not matter where we are, plastic items surround us everywhere. They allow us to maintain food safety and better hygiene, receive medical treatment and even perform acts of personal hygiene such as brushing our teeth and styling our hair. It is when we begin to think how many are created through this method that we begin to realize how important the process is.


Many of the plastic items which we use on a daily basis have all been created the same way. Plastic injection molding methods have been used in order to create items that are used in many different fields including the medical field. Even household items such as toothbrushes and hair clips can be created using these methods. Although materials may have changed slightly, the fact is that plastic injection molding methods are still the same at their most basic level. The process still calls for heated plastic to be injected into a mold and then chilled. Usually chilling occurs thanks to the passing of coolant over and around the molding chamber where the plastic is being shaped. The hardened plastic forms are then ejected and trimmed down so that they are ready for sale or use.


A later form of plastic which was developed soon after was easier to shape into different items. This was the first real step towards modern injection molding processes. As soon as a more versatile form of plastic was invented, the plastic injection molding methods similar to those we use today were also created. There have been some changes to the plastic injection molding methods but the larger changes have been to the plastics themselves. Now, they are available in a much wider variety than they were in the late 1800’s. It is now possible to color the plastic that is being molded since dyes and other chemical additives can now be mixed in with the plastic granules themselves. Specific additives can give plastics unique qualities that can make them more suitable for use in different industries and products.

You may be interested to learn that the molds themselves have also changed. Early molds were made in two parts: the shaping cavity and the ejection portion that allowed the finished product to be ejected so that it can be trimmed and utilized. Now the complexity of the molds and the detail that they have has also altered; although, there are still two main portions: the mold and the ejector.

Although many items made with these methods had been created between the late 1800’s and the 1940’s, the war effort, and its need for many items which could be made using these methods, caused changes in the process to be developed. The screw-type injector process was also developed at this time as well as methods that allowed different additives to be mixed in with the plastic that was to be molded. This was a huge advancement and one of the first real changes to the molding process itself.

Working and living in the modern world would not be possible if it was not for the products made using the injection molding process. They surround us and make our lives safer and much more convenient. From personal care products to containers that hold food and water, we live in a world that is influenced by plastic injection molding and the products that they produce.