Polymer processing is an engineering field which deals with the conversion of synthetic high polymers into shaped articles ready for use. Impressive developments in the field of polymer processing in the last 20 years or so were precicipitated by the need to process plastic materials with an ever-increasing rate of production within stringent quality requirements. One of the most interesting methods for shaping plastic products is molding which involved all the possible ways for stuffing molds with thermoplastic or thermosetting polymers. Injection molding, compression molding, and transfer molding have now become some of today's routine approaches to plastics shaping.