Bruce H. Maddock died last year at age 85, but his work endures, thanks to innovations like the Maddock Mixer and his screw ``push-out'' testing method.
His very scientific soul lives and breathes inside computer and mathematical models used today.
In the late-1930s, Maddock began his quest to figure out extrusion. Back then, the rubber industry dominated the process. Plastics was still an awkward child.
Fast-forward 30 years. Beginning in 1969 at Union Carbide Corp. in Danbury, Conn., Dave Smith, a young engineer, spent four years with Maddock to develop an early computer model for single-screw extrusion.
``The computer models today are really all based on Bruce's experimental work,'' said Smith, now vice president of engineering for Battenfeld Gloucester Engineering Co. Inc. in Gloucester, Mass.
Maddock died Nov. 9 in Lakewood, N.J., just a month after the Plastics Academy told him he was picked for the Plastics Hall of Fame. He had been afflicted with emphysema for several years. His daughter, Nancy Maddock, will accept the award at the banquet Thursday night at NPE.
Low-key and modest, Maddock possessed a wealth of information and shared it freely, according to people who knew him. Extrusion leaders never missed his technical papers at the Society of Plastics Engineers' Annual Technical Conferences.
George Kruder, former HPM Corp. vice president of research and development, called Maddock ``the world's greatest contributor to commercially useful extrusion technology.''
Kruder, himself inducted into the Plastics Hall of Fame in 1991, has fond memories of Maddock: ``He came to my laboratory at HPM and did a number of tests with us on bigger-scale equipment than he had in his own lab. The thing that impressed me most about Bruce is that he was so wonderful in getting down to basics. He was a good teacher, he was a good experimenter, and he basically did more than anyone else that I know of ... to advance technology.''
Smith recalls being somewhat in awe during their first meeting.
``When I was introduced, I was told that this man is the world's expert.
``Bruce was a very quiet individual, and Bruce had tremendous practical knowledge,'' Smith said. ``He had a wonderful filing system, where you would say to him `What would happen if I ran this polymer in that extruder?' He would think for a while, jump out of his chair, go over to a file and pull out test results from 15 years ago.''
Maddock's career began in 1928. Fresh out of high school, he got a laboratory job in a Bakelite Corp. plant in his hometown of Wyandotte, Mich. He earned a bachelor's degree in engineering physics from the University of Michigan in 1934.
``I was graduated at the height of the Great Depression in 1934 when jobs of any kind were essentially nonexistent,'' he said while accepting an SPE award at a 1988 Antec. ``I ended up in mid-1935 with a new wife and an old Model A Ford, back in the same job I had started with in 1928.''
But Bakelite soon moved him to its research department in Bloomfield, N.J.
Carbide, then called Union Carbide and Carbon Corp., bought Bakelite in 1939. Maddock again was transferred, to a Carbide lab in Lakewood, Ohio, to develop extrusion coating of electrical wire and cable.
``It was recognized early in the game that the rubber extruder, for lack of heating capacity and residence time, could not handle cold-fed material. An obvious step was to make the barrel and screw longer,'' Maddock said in his speech. That worked.
In 1942, Maddock left Carbide briefly to become chief engineer at the fledgling Intelin Division of Federal Telephone and Radio Corp. He helped develop plastic-insulated coaxial cables for radar in World War II. He returned to Union Carbide in 1945 and stayed until retiring in 1974.
His research was fundamental. Can't see inside the machine? Maddock perfected a simple, but revolutionary, screw ``push-out'' technique, also called ``screw-freeze'': Run material through the extruder, then suddenly stop the screw and freeze up the material by rapid water cooling. The filled screw is pushed out of the machine with an air cylinder and the plastic helix unwrapped for examination. By dropping colored pellets into uncolored resin, Maddock was able to track flow, melting and mixing.
Extrusion engineers still use the term Maddock Mixer to describe a fluted barrier section of the screw.
``How many devices do you know that have remained in use, basically unchanged, for 25 years?'' asked Smith, now of Battenfeld Gloucester. ``That tells you how good the device really was.''
In a speech to SPE, Maddock himself called the extruder ``one of the most important pieces of machinery in the modern industrial world.''
``Stop to realize that almost every ounce of thermoplastic material in existence today, either as a finished or future product, has probably been through an extruder at least once in its lifetime.''
