The processes involving the working of viscous hot glass-the only topic of this book-are basically different from those customary in other technologies. The strong temperature dependence of the working properties of glass, particulary of its viscosity, require the exact .co- ordination of cooling and forming. For this reason the temperature conditions in the forming parts of the machine and the timing of the process are of prime importance. This particularity of glass as a material as well as the diversity in type and quality of glass products explain the specificity of glass machines in the field of machine design. The literature on glass machines is sparse and scattered. Because of the increasing specialization in the field of glass machines, it is not only the beginner but also the expert who finds it hard to obtain insight into the entire field of glass forming. In response to this situation Committe IV (" Glasmaschinentechnik ") of the "Deutsche Glastech- nische Gesellschaft", the German glass society, decided to suggest and sponsor the publication of a book on glass machines aiming at the comprehensive presentation of the state of the art as well as the histor- ical development. Because of the great specialization in the field the publishers had to secure the help of several colleagues whom they wish to thank for a decisive role in this book. Thanks are also due to the glass and machine factories providing material.
