The Calendering of Plastic Materials

Abstract

Abstract Many industries, notably the paper, linoleum, rubber, and steel industries, use a rolling process to form or otherwise treat sheets of these various materials. To most engineers, perhaps, the term “rolling” brings to mind only the rolling of steel or aluminum—solids with definite yield points. Several mathematical studies of the rolling of such materials have already been made. In those studies, any shear stress beyond the yield stress is neglected. The plastic materials handled by other industries, however, do not often have the definite yield point of steel, or, after yielding takes place, they may behave more like liquids of very high and usually variable viscosity. Shear stress beyond the yield point, due to viscosity, cannot therefore be neglected. Consequently, a different approach must be made if a mathematical description of the process is to be formulated. Such an approach is made in this paper.