There’s no doubt that life would be very different if it weren’t for the various contributions to plastic injection molding. I mean, think about the number of things in your house that would be impossible without the process! Everything from your child’s toys to the window frames around your house have gone through plastic product manufacturing. It has become a process that we have thus far relied on heavily, and one might say that it is now permanent to our way of life, at least until something new comes along. At the current rate that plastic injection molding is going though, it just doesn’t seem like there can be much competition in the field. Several decades of work and research have been dedicated to the field of plastic injection molding, and with excellent results, as is clear by the number of products manufactures produce and consumers consume. But where did plastic injection molding come from, and how does it work?
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.
Injection molding was invented by John Wesley Hyatt in 1868; this was the first time the process had ever been seen before. He began to make billiard balls by injecting a material called celluloid into sphere-shaped molds. Celluloid was invented in the 1820’s, and was most often used because it looked similar to ivory or bone. Soon after his first steps into plastic injection molding, Hyatt looked to make the process easier on himself, so he created the very first injection molding machine (which employed the use of a plunger-type piece).
From then on, plastic injection molding began to rapidly rise in popularity. The demand for plastic products was at an all time high, and it seemed that Hyatt’s first machine could not hold up to all of the demand from consumers. Finally, in 1946, James Hendry revolutionized the machine and with it, the industry. He replaced the part of the plunger with that of an industrial-sized screw, which multiplies the speed and thus the quantity of the plastic injection molding process.
When purchasing a plastic to use in the injection molding process, manufacturers have a few variables to cover. These can include the budget that the company is running on, the type of product being made, and the estimated output quantity. Most plastics, however, come in the form of small beads or pellets, often referred to by those in the industry as resin. Common types of plastics used in the process are acrylic, teflon, delrin, polyvinyl chloride (PVC), polyamide, polystyrene, and more.
Safety should always be a concern when it comes to manufacturing plastics, they are non-degradeable, which isn’t great since we consume so much of it every day. On the bright side, awareness for recycling has increased exponentially in the last few years, and encouraging other people to recycle is always a main topic at college campuses! Thermoplastics have the ability to be heated and reheated as many times as necessary, so recycling is so important!
Once the plastic is chosen, it’s time for the plastic extrusion process to really begin. First, engineers load the beads (or resin) 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.
Then, the plastic goes through a filtering device to rid it of any contaminants it may have collected. By doing this companies eliminate the risk of ragged edges, or plastic products that simply aren’t uniform. Finally the plastic enters a die, whose primary purpose is to form the mold into the shape of the final product. Molds can be made of expensive steel, but this proves to be much more durable, if a company is watching its expenditures they can opt for the less durable aluminum or beryllium-alloy metal.
There is a brief cooling period so that the plastic hardens and shapes perfectly and then either the toy, window frame, or hurricane shutters. It doesn’t take a scientist to figure out that plastic injection molding produces a mass quantity of products. Without the process and all of the work done by polymer extrusion companies, we’d be living very different lives!
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