an apparatus includes an injection molding machine , a hot runner apparatus attached to the molding machine , and a mold defining a part cavity . the mold is attached to the molding machine and operably engages the hot runner apparatus . the hot runner apparatus has secondary nozzles that engage respective sprue assemblies on the mold for communicating melted plastic material to the mold cavity . each sprue assembly includes a movably mounted sprue and a stress - reducing mechanism with spring washers that support the sprue to provide sufficient force to eliminate leaking at abutting contact surfaces against the secondary nozzles , but that allow limited movement of the sprue to reduce excessive stress focused on the respective sprues . since the stress - reducing mechanism is located in the mold , each stress - reducing mechanism can be tailored to the particular needs of that particular mold and the particular melted material being processed .