The History of Injection Molding

The History of Injection Molding

You’ve heard the term Injection Molding, but what exactly is it and what can it do for you? In simple terms, this manufacturing process involves high pressure injection of a molten plastic material into a mold cavity. Once the material solidifies and conforms to the contours of the mold, a sort of blueprint is created for future production runs. That goes for everything from bottle caps, to brochure holders, to pocket combs, musical instrument parts, and auto components. Virtually anything can be injection molded…the sky’s the limit!

In more scientific terms, Injection Molding actually traces back to the first condensation polymer in the mid-19th century. It was American inventor John Wesley Hyatt who patented the first Injection Molding machine in 1872. Hyatt’s device was like a large hypodermic needle that injected heated plastic through a heated cylinder into a mold. Hyatt called his resulting compound “celluloid” and it found immediate use in billiard balls and, of course, the motion picture industry.

Over the next few years, moldable plastics made leaps and bounds with new developments like Cellophane, Nylon, Polyvinylchloride (or PVC), Teflon, and Polyethylene. It was World War II when the control over speed and quality was tested by huge demand in mass production. The value of injection molding as a manufacturing process took off and never looked back.

That same high-capacity capability is also at work now on high volume orders at Plastic Products Mfg (PPM). Our Mexico facility is especially geared for high-volume production runs in various plastic compositions. A type of clamp keeps the injection unit in place while the thermoplastic material is fed into the mold. Intense hydraulic pressure and rapid cooling allows high-quantity runs automatically…and that translates to fast turnaround on both standard and custom plastic products. In PPM’s case, that means a variety of POP Displays can be processes and shipped quickly. It’s the same principle Hyatt introduced, taken to 21st century manufacturing levels with new technology.

The molds themselves are typically built with precision CNC machining. Using a form of electrical discharge machining (EDM) has opened the door to more intricate, difficult mold designs and can even be used to shape molds that have already hardened. And once the mold is set, production costs are minimal because the tooling work’s already done. The complete cycle of Injection Molding is also relatively short, from injection of the polymer material through the cooling process…when the mold is opened and the hardened, finished product is “ejected.” Behind the scenes at PPM, the latest chapter in this historical process is in high gear all day, every day!