Injection molding is one of the well known plastic parts production method. The technology for injection molds and molding machines is quite developed and the new research is now focusing on plastic parts processing. In this book the effect of processing parameters on injection molds with different runner systems have been studied analytically and through software analysis. Experimental results have also been discussed. A chapter on designing of injection molds with hot and cold runner systems is also included. The material presented in this book is helpful in understanding the role of hot and cold runner systems in injection molds processing.