Plastic injection molding has been providing plastic mold parts for almost two whole centuries now and counting! If it wasn't for the brilliant minds of those in the field, we may be without hundreds of things that we've so far grown dependent on. The plastic injection molding process is responsible for producing things as commonplace as keyboards, toys, and power tools, so you can see how vital it is to our current way of life.
Since starting out on my plastic injection molding research, I have gained such a vast array of information on its history and its current workings, that I have been compelled to let other people know about it. The thing that surprised me the most about the process was how little I had heard about it until just recently! You would think that with something so widely used, producing so many important amenities, that conversation about it would be as commonplace as the products it produces! So what is this plastic injection molding, and where did it come from?
Throughout the course of industrialization, there has been a lot of pressure on the reduction of industrial waste. This is because many industrial processes can be harmful to the environment, but plastic injection molding is actually one of the safest! Since plastic injection is used in such frequency, it's a good thing that it isn't highly dangerous to the environment, otherwise we'd have to look for new ways to produce so many things. Thankfully, plastic injection has been fine-tuned to perfection ever since its debut in 1868.
John Wesley Hyatt came up with the idea when he began to ask himself how to make a full set of billiard balls easier than he had previously. He began to inject a material by the name of celluloid into spherical molds that he cast, and thus injection molding was born. Celluloid was discovered several years prior to Hyatt's use of it, and was sometimes used to mimic bone or ivory in products. Soon, Hyatt's business expanded, and he felt that his process should too, so he created the very first injection molding machine, which was run by a plunger mechanism.
Injection molded parts soon began to get very popular very quickly, and the industry was really allowed to expand. Almost a full 100 years after Hyatt's billiard ball success, James Hendry completely turned the process in a new direction. He replaced the plunger style of Hyatt's old machine with an industrial screw. The introduction of the screw was like nothing the industry had ever seen before, it immediately increased production tenfold and was adopted by almost all manufacturers in the business.
The first thing for a manufacturer to consider when beginning the plastic injection molding process is the type of plastic that they want to be creating their products from. There are quite a few variations of plastic that are too unsafe, and plastic companies make it their duty to produce safe goods for their customers. That's why it's important to use the right kind, usable plastics consists of polyvinyl chloride, acrylic, Teflon, Delrina, and polystyrene; which all come as raw beads referred to as resin.
Making sure that plastic is safe and environmentally friendly is important to consumers and producers alike. So how do we deal with the problem that plastic isn't biodegradable? It's as simple as recycling; most plastics can go through the plastic intrusion molding process as many times as necessary. Recycling is cheaper and easier for everybody involved, including the environment! Once the plastic is chosen, it's time for the plastic extrusion process to really begin. First, engineers load the beads into a device referred to as a feed hopper, which basically allows for the plastic to be gravity-fed into the rest of the machine. The hopper pours the resin into a barrel-shaped heating cylinder, which heats the plastic at temperatures up to 400 degrees Fahrenheit. As the cylinder is heating, the screw will start up, using extreme force on the melted plastic.
After this, the molten liquid plastic passes through a complex series of thin screens, which are meant to catch any flaws or contaminants in the molten resin. These screens are held together by a puck-like piece of metal with holes drilled into it. The plastic mold is pushed out through these holes and into the final part of the machine called the die. The die is responsible for giving the plastic its shape, whether it is a knob or a window frame!