William M. Lester
Pyro Plastics
Inducted 1986
William Morris Lester was an inventor, innovator, and entrepreneur who helped revolutionize the American plastics industry. Born in Brooklyn, New York, to Russian immigrants, he earned a degree in mechanical engineering in 1928 from Worcester Polytechnic Institute, where he also revived an inactive fraternity, Alpha Epsilon Pi.
Lester first worked at Precision Castings Company of Syracuse, New York, and then founded the Lester Tool and Die Company in Cleveland with his father. As chief engineer, he perfected mold-making methods, took out six U.S. patents, and licensed his design for die-casting machines to the Reed-Prentice Machinery Company, a leading supplier of die-casting and molding machines. The Lester Phoenix Corporation of Cleveland, led by Lester’s father, continued manufacturing and selling the machines.
Lester obtained at least 20 design patents throughout his career, including a “dispensing closure” for squeezable containers and a rotary internal combustion engine. In 1935, Lester established the first injection molding company in Leominster, Massachusetts, for the Commonwealth Plastics Company. That year, he designed the automatic molding machine (the Lester machine) that injected melted plastic into a cavity created by metal slabs that joined together, much like a waffle maker. The unique hydraulic system of this machine could generate several thousand pounds per square inch of hydraulic pressure. Though injection machines already existed, they routinely took several minutes to create a molding, whereas the Lester machine usually reduced the cycle time to less than one minute. The machine was essential to the growth of the plastics molding industry at the advent of World War II.
In 1939, Lester founded (with his first wife, Betty, who died in 1993) his molding company, Pyro Plastics, in Westfield (Union), New Jersey, which he managed until 1972. Pyro Plastics became a leading producer of custom-made injection molded parts and is remembered today for its line of popular toys. After selling Pyro Plastics in 1972, Lester turned his attention to packaging that would prevent tampering or show evidence that tampering had occurred (thought to be the first tamper-evident packaging).
Lester was a founder of the American Technion Society, which supports The Technion University in Israel, and he led the formation of the U.S.-Israel Plastics Corporation in Holon, Israel, which produced irrigation supplies and was an active member of many American plastics organizations, such as the Society of Plastics Engineers.
Areas of Expertise:
Plastics machinery, Plastics management and sales