A History of Mold Making

Mold making has existed for thousands of years. Molds have been found around the world from ancient times including a stone mold dating back to the bronze age used to make spear tips to a mold from ancient Greece that was used to make figurines and even a wooden mold to make candy in Sri Lanka. The history of mold making shows molds were used across cultures for defense, hunting, and leisure, so ancient civilizations understood their value early on.

Injection molding traces its roots back to more recent times. The first recorded event for injection molding is 1872 when John Wesley Hyatt and his brother Isaiah patented the first injection molding machine. According to Wikipedia, in 1903 German chemists Arthur Eichengrün and Theodore Becker invented the first soluble forms of cellulose acetate, which can be used to make items such as eyeglass frames, and Eichengrün developed the first injection molding press in 1919. As a natural follow-on, Eichengrün patented the injection molding of plasticized cellulose acetate in 1939. World War II created a huge demand for inexpensive, mass-produced products in the 1940s, so injection molding saw an increase in use.

After World War II, in 1946, James Watson Hendry continued the momentum of injection molding when he built the first screw injection machine. Screw injection machines today are used in the majority of injection molding, showing that even though there have been few major innovations in the injection mold industry each innovation has meant a great deal to the industry. This machine allows more control over mold injection speed and the quality of items made using injection molding. It also allows for color to be added to the material being molded and mixed thoroughly before molding.

Hendry would then go on to develop the first gas-assisted injection molding process in the 1970s, which allowed the production of complex, hollow articles that cooled quickly. This led to greater design flexibility as well as better strength and finish of manufactured parts. Because of the rapid cooling the process also reduced production time, cost, weight and waste. By 1979, plastic production overtook steel production.

The Toolroom began producing superior quality plastic injection molds in 1978 and has industry experience dating all the way back to 1946, so has seen the plastic injection molding industry through the past half-century-plus of innovation and change. With its state-of-the-art molding facility and injection molding processes, The Toolroom is the St. Louis area’s leading plastic injection molding shop.