Development of Internal-Mixer Technology for the Rubber Industry

Abstract

Abstract The early rubber industry was largely based on mixing with two-roll mills. The coming of the pneumatic-tire industry associated with the rise in popularity of the automobile brought increasing production and large quantities of fine particles and poisonous vulcanization accelerators. This made necessary the introduction of internal mixers into the rubber industry by the second decade of the 20th century. This paper treats the development of internal mixer technology from its origins in the 19th century to the late 1980's, largely through critically following the patent literature. There seems to be no other critical review of the development of internal mixer technology, and this manuscript is unique. Briefly, the technology development we will describe is as follows: There were two conflicting design approaches, one based upon a single-rotor masticator devised by Thomas Hancock in the early 19th century and a second based upon two nonintermeshing counterrotating rotors which were championed by Paul Pfleiderer later in that century and manufactured by his firm, Werner and Pfleiderer. As late as the mid 1920's, machines based on both the single rotor and two nonintermeshing rotor designs competed with each other for the internal-mixer market. The insight, perseverance, intensity, and dedication of Fernley H. Banbury and the Birmingham Iron Foundry (later merged into Farrel-Birmingham) brought about the design which proved to be the paradigm of the industry. Innovation, however, continued in internal-mixer technology. The most striking new development of the post-Banbury period was the invention and application of intermeshing counter-rotating rotor mixers in 1934 by Rupert Cooke of Francis Shaw and Company. Werner and Pfleiderer developed and worked with many internal-mixer designs and in time began to manufacture both nonintermeshing- and intermeshing-rotor machines. In the 1950's and 1960's, Kobe Steel and Pomini began to manufacture internal mixers as Farrel-Birmingham licensees. This period also saw developments of nonintermeshing-rotor internal mixers. The basic Banbury design maintained its position and its manufacturer, Farrel-Birmingham (later Farrel), devised improvements of it. Innovations in the design were also made from the late 1970's by Kobe Steel, now operating independently. Pomini also began operating independently, manufacturing not only nonintermeshing machines but a unique intermeshing-rotor machine with variable clearance between the rotors. In recent years, we have seen the development of increasingly improved control systems for the internal mixer.