Many don’t exactly find injection molding interesting, let alone even know about. However, I’ve made it my personal goal to, at the very least, get people to begin started on the road towards finding out how things are made! One can easily forget that what they just bought at the store was in fact made by the inventions of people over several years as well as by the hands of specialists and people with a variety of expertise. In fact, this is so often overlooked that it can be pretty fascinating to learn all the ins and outs of plastic extrusion. Man and machine working together in order to make it easier on the population. It’s really a beautiful thing to watch and while researching and working alongside specialists in the industry, I’ve grown to actually respect them for their hard work and dedication. They’re responsible for so many plastic products and byproducts that have been in use for years, and will be in use for years to come.
It’s extremely important that you understand the molding process. But to start you off, I think it’s smarter to just describe it as simply as possible. What polymer molding actually does is to heat and shape thermoplastic and thermosetting plastic in order to manipulate it into a finished product. This is done with the help of a number of people (engineers, moldmakers, and a number of other specialists).
To really appreciate everything that goes into injection molding, it’s a good idea to track its beginnings. Throughout the 18th and 19th centuries, contributions to the plastic manufacturing industry have been enormous. It all started with the beginning of synthetic plastic. A man by the name of Alexander Parkes, an inventive thinker from Britain discovered a material which he named Parkesine.
Parkesine, as might be expected for what is essentially the first of its kind, had several faults. First of all, and really most importantly, Parkesine was highly flammable. This led to an incredible amount of risk for all those working on it. Moreover, the finished products were expensive, but flimsy, and were widely known to crack and break. Thankfully, In 1868, American John Wesley Hyatt improved Parkesine.
Hyatt titled his invention celluloid, and this plastic material could be molded cheaper, easier, and more durably. This invention really paved the way for the industry to start manipulating injection molded products. Four years after the making of celluloid, John and his brother Isaiah Hyatt worked together to create the prototype of the very first plastic extrusion machine. This machine was actually quite simple (in comparison with the other extrusion machines used today).
Following the introduction of Hyatt’s polymer extrusion machine, the industry rapidly grew. Now that the process of plastic profile extrusion was really being set into play, new ideas and innovators were stepping up to the plate, ready to improve. Different versions of Hyatts’ machines were made in order to produce different products, including collar clips, hair combs, and even buttons.
During the 1940’s, a spike in the demand of plastic products. Companies were forced to turn out huge numbers of products, but too many simply couldn’t keep up with the orders! So, in 1945, James Watson Hendry took it upon himself to create a bigger and better plastic manufacturing machine. This particular machine was the first of its kind to employ the use of a screw, and specialists found that they were able to better control the speed of the injection, which in turn greatly increased the quality of the final products.
It was also found out that since the screw was now mixing the molten plastic products, other things could be mixed in with it. By adding different dyes, all sorts of new colorful products could be made, expanding the industry exponentially. Even now, most injection molding machines use a type of screw injection molding. Hendry also worked for thirty more years and release an injection molding machine that applied the use of gas, hugely reducing the use of important resources.