History of Plastic Injection Molding
In 1851 Alexander Parkes invented the first man-made plastic in Britain. He demonstrated it at the 1862 International Exhibition in London. The material that he named “Parkesine” was derived from cellulose and could be heated, molded, and retain its shape when cooled however it was expensive, highly flammable and prone to cracking.
In 1868 John Wesley Hyatt an American inventor improved upon Parkes’ material and developed a plastic material that he named Celluloid. He and his brother Isaiah patented the first injection molding machine in 1872. Simple by modern standards it operated in a similar manner to a hypodermic needle, using a plunger within a heated cylinder to melt and inject the material into a mold.
This simple process was used mainly to produce household items such as combs and buttons until world war 2 brought with it a demand for inexpensive mass produced products.
In 1946, American inventor James Watson Hendry built the first screw injection machine, which allowed much more precise control over the speed of injection and the quality of articles produced. This machine also allowed material to be mixed before injection, so that colored or recycled plastic could be added to virgin material and mixed thoroughly before being injected.
Today plastic injection moldings can be found everywhere. The materials now available for designers and engineers to choose from allow them to create parts for all industries and all applications. From soft materials used in seals and gaskets to the most rigid, tough and durable materials that are used in place of metal in many traditional applications.