What you need to know about Plastic Injection Molding
Do you know how we get many of the complicated plastic items that make our lives safer, more hygienic and much more convenient? Many of them are formed by a process known as plastic injection molding. This is a manufacturing method that has been in use, in one form or another, since 1872. Since then, the process has been refined to make it more efficient and to enable manufacturers to use different types of plastics that have different qualities.
When plastic is melted it can be molded into a variety of different shapes as it is extremely malleable.
Manufacturers needed to find a way that melted plastic could be forced into a mold in order to shape it into three dimensional shapes. It was for this reason that the first injection molds were developed.
The Plastic Injection Molding Process
The plastic that is used in plastic injection molding is in pellet form. A mixture of different types of plastic can be used and other ingredients, such as colorants can also be added. The specific type of plastic used will depend on the qualities that the finished product requires. The plastic moves from a hopper to a heated barrel, where it melts. This melted plastic then is pushed into a mold through a nozzle by a plunger, in much the same way that liquids move through a hypodermic needle.
Although the chamber is heated, the mold is kept at a cooler temperature. This cooler temperature causes the plastic to cool and harden. Once that has happened it can be removed from the mold and any finishing touches such as smoothing out ridges or removing excess material can be completed.
How Molds Are Created
Molds are completed using a machining process. They are generally made up of two pieces although some molds may be very complex and have more than two pieces. One part of a basic mold is the injection mold and the second is the ejector mold. The parts are generally formed in a cavity in the injector mold and the ejector mold plays an important role in ejecting the finished product that has cooled and solidified.
Very fine details can be worked into the molds so that they are transferred to the final product. This can be done in a number of ways but the process has become much simpler now that computers can play a role in designing and manufacturing the molds.
Objects Produced By Plastic Injection Molding
There are many products that are produced using various types of plastic injection molding techniques. These can include household items such as combs, hair barrettes and toothbrushes. Many plastic toys are made using plastic injection molding. The automotive industry also tends to use plastic injection molding in order to create automotive parts including body panels.
The medical industry also often uses products created using plastic injection molding. Tubes and piping are made using this process and these are used in many different areas including diagnostics, surgery and general medicine. The canula, silhouette and reservoir used to deliver insulin in pumps used by Diabetics are made of plastic. Plastic molded injection parts facilitate a better lifestyle for people requiring specialized care.