A Brief History of Plastic Injection Moulding
The importance of construction materials to human civilization is evinced by the classical system for naming the ages of history: the stone age, the bronze age, and the iron age stand out in particular. The importance of fabrication materials has only increased through time. Our modern civilization is built largely on a few key materials – stone, metal, wood, and plastic come to mind.
Of these four materials, stone and wood have the longest histories, having been used since people first constructed tools and buildings. Metals have been used for thousands of years as well, although it was only with the development of steel in the late 19th century that the use of metals came into its own.
Despite the importance of stone, wood, and metals to modern society, one material has come to dominate our modern lifestyles: plastics.
The first commercial use of plastic, in 1865, was for the production of billiard balls, which had previously been made using ivory.From these humble beginnings, plastics have come to play a key role in modern society, allowing for the production of cars, computers, electronics, food storage and preparation products, medical products, clothing, and countless other fundamental technologies that we now take for granted.
A key moment in the history of plastic came during the Second World War, when allied supplies of rubber fell short of demand. An extensive research program conducted by the United States government led to the development of a plastics replacement for natural rubber. A number of “failed” formulations turned out to be useful for other purposes.
As our ability to formulate plastic materials improved, so did our knowledge of methods for shaping plastics to meet our needs.
In 1968, Josiah and John Hyatt became the first to inject hot cellulite into a mold using a plunger. Their simple moulding technology allowed for the production of small, simple, but useful objects such as buttons and hair combs. However, the applicability was limited: it was difficult to precisely control the rate of material injection. In addition, materials could not be premixed before injection, which limited the development of plastic alloys, plastic recycling, and colouring.
The forebear of the modern screw injection plastic moulding process was developed during the wartime rubber shortage. This type of machine allows for mass production of precisely shaped components. The recent development of mechanization, 3-d printers, and computers have led to the ability to make increasingly precise moulds. Plastics will continue to play a major role in our society, and as technologies continue to advance, we should expect to see plastics being used in new and innovative ways.
To learn more about the history of plastics, take a look at these interesting articles:
A general history of plastics – provides more detail about the series of discoveries leading to modern plastics.
An old documentary – it’s interesting to see how plastics were perceived when they first became widespread in the 1940s.