hot runner system is used for production of large parts or long flow length. It saves material, lowers the part cost, improves part quality, shortens the cycle time, and improves production yield. It is popularly applied to plastic injection mold. From the mold design point of view, it complicates the mold structure and increase it’s cost significantly. Hot runners are a commodity, available from multiple supply sources. Due to it’s high cost, hot runner is usually listed as a separate cost item.