By Bryan A. Crawford, Nanomechanics Inc., Harold J. Herzlich, Herzlich Consulting Inc., and Erik G. Herbert, University of Tennessee. In 1916 Fernley H. Banbury patented the first "Banbury" tangential mixer. Based on the principles of the two-roll rubber mill it was intended to remove the influence of the operator and significantly reduce the time taken to mix a batch of rubber. Some 16 years later the first intermix intermeshing mixer was patented, employing the same basic principles as the "Banbury." So, what's the difference?● Both types of mixer perform the same fundamental task of mixing rubbercompounds;● Both employ the same basic principles to achieve this aim; and● Both styles of mixer are market leaders in the increasingly complex businessof mixing increasingly complex rubber formulations.It is the differences between the mixer types that provide specific advantages to specific markets, and it is important to understand these differences to choose the right style of mixer for the right application, which is detailed in this paper.