Who Invented Plastic Injection Molding?

plastic injection molding
three different tinted polymer resins

Plastic is so common, affordable, and convenient that we produce about 300 million tons of it every year. But what’s plastic injection molding – and who came up with this idea to make things so easily?

This is a simple process: molten plastic is poured into a mold and cooled. It then takes the shape of whatever mold it has filled. So, everything from water bottles to healthcare supplies to automotive parts to even Legos are made with this process.

In other words, today’s world wouldn’t go around without plastic injection molding. Who can we thank for this vital invention? Let’s get to know the plastic injection molding inventors and how they came up with this brilliant idea.

Meet John and Isaiah Hyatt

Brothers John and Isaiah Hyatt patented the first plastic injection molding machine in 1872. But how did they get to that point?

John had a history of inventing much-needed products and processes even before getting to plastic injection molding. In 1869, he patented his method for creating billiard balls from gum shellac and fibrous materials. He pioneered this process when the original billiard ball material, ivory, became too rare and pricey to use for a game of pool.

On to Plastic Injection Molding

With his first patent on the books – and a company creating billiard balls – John continued inventing. In one experiment with pyroxylin, a type of plastic, he found that he could mold it with the help of moderate pressure and heat.

Three years after filing his first patent, he and his brother Isaiah had another process worthy of a patent: plastic injection molding. Their process was very simple compared to the plastic injection molding of today. But it did expand plastic manufacturing of products like combs and buttons.

Others Improved

The Hyatt brothers were the injection molding inventors, but others helped refine the process later on. At the turn of the 20th century, German scientists Arthur Eichengrun and Theodore Becker found that they could make cellulose acetate soluble. This proved much less flammable than previous ones used in injection molding.

By the 1930s, the plastic industry was booming, and plenty of materials we still use today were invented. These include polyvinyl, polystyrene, and polyolefins.

But perhaps the biggest boom in this industry and the mass production of these products came with World War II. Manufacturers used this process to create the mass of supplies needed for war. But they also used plastic to replace some of the materials that they no longer had access to, as supply chains got cut off.

Plastic Injection Molding Today

Nowadays, the process remains a vital part of the world’s manufacturing process. You certainly have plastic injection-molded items throughout your home.

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