Modern computer modeling tools can help define the best way to produce quality injection molded parts. They provide a way to quickly evaluate different processing options, taking into consideration part geometry, resin characteristics, process variability and plant economics. They are tools for optimizing the technical and economic aspects of producing consistent quality parts.Computer models can be used to: determine mold filling conditions, weld line location and integrity, physical strength and appearance. define the molding conditions necessary to meet part tolerances. forecast shrinkage of critical dimensions, and compute the resulting cavity dimensions required. calculate production costs, and define production planning data.