Rheology and Melt Flow in an Injection Mold

This chapter will present both a foundation in melt rheology and flow of plastics in a mold. Rheology is a reasonably well established scientific field, but the science of how polymer melts flow in a mold is not so well understood. The rheology of polymer melts is quite complex and can include influences of shear, temperature, and pressure, converging and diverging flow, elastic effects, tensile viscosities, etc. As this is not a book on rheology, this chapter only provides an introductory overview of some of the issues that most molders and mold designers should understand. This foundation also ties into a number of the later chapters.