By: Fabiola Grosshan
Submitted: 2010-06-23 03:21:00 | Word Count: 380
Injection molding is a manufacturing process in which material is fed into a heated barrel, then mixed and shaped into a mold cavity. When the material hardens, it takes the solid form of the mold. This process is used for manufacturing mass market parts for various products, including small component parts for car panels and other vehicle parts, as well as injection molded cases for a wide variety of products. Injection molding is commonly used for such things as liquor packaging and custom product packaging, which we come across every day at our local grocery stores and supermarkets.
Plastic
The history of injection molding is closely linked to the invention of plastic. The first man-made plastic was produced by Alexander Parkes in 1851, and he exhibited his invention publicly in 1862 at the International Exhibition in London. While Parkes’ invention was impressive for its shape-retaining abilities, it was too expensive to be commercially viable and highly flammable as well as prone to cracking.
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The First American Injection Mold
A breakthrough came in 1868 when American inventor John Wesley Hyatt created Celluloid, an improvement on Parkes plastic (which Parkes called “parkesine”). Hyatt’s celluloid plastic was much more durable and more effectively molded. His injection machine was fairly simple, using a large hydropermic needle and a plunger to inject plastic into a heated cylinder mold. The injection mold industry progressed slowly at first, with buttons and hair combs being among the first simple items it produced.
WWII
It took World War II and the increased demand for mass produced parts it brought to push the injection molding industry to the next level. The industry expanded rapidly in the early 1940s; in 1946, James Watson Hendry invented the screw injection molding machine, which allowed material to be mixed before injection. Hendry’s machine is the predecessor to the injection molding machines we use today, machines that still employ Hendry’s basic model. Hendry added a few more developments though, mainly in the 1970s when he developed the first gas-assisted injection molding process, which allowed for the production of much more complex component parts than previously possible.
