Hot runner systems are used frequently in injection molds to control the flow of the melted plastic in the part. Melted plastic material is injected from the nozzle of the injection machine into the sprue bushing and into a heated manifold that distributes the melted plastic through hot nozzles and into the cavities. Hot runner systems are used to control the quality of big parts that need a long plastic flow as well as in multi cavity and family molds.