Injection Molding Machine

An injection molding machine is a piece of manufacturing equipment that heats plastic material and forces it under pressure into a mold cavity to form a shaped part. American inventor John Wesley Hyatt and his brother Isaiah built one of the earliest injection molding machines and received a patent for it in 1872; their device worked much like a large hypodermic needle, using a plunger to push heated plastic through a cylinder and into a mold. The industry grew slowly through the early twentieth century, producing simple items such as collar stays, buttons and combs, until American inventor James Watson Hendry developed the first screw injection machine in 1946, which gave far more precise control over injection speed and product quality and allowed materials, including colored or recycled plastic, to be mixed before injection. Hendry advanced the technology further in the 1970s by creating the first gas-assisted injection molding process, enabling faster cooling and the production of complex hollow parts; by 1979 plastic production had overtaken steel production by volume, and screw injection machines remain the dominant type in use today.